While the gadget that adjusts the flow return temperature is a great idea, it basically means that the radiators in the house aren't big enough. Either the radiators were installed in an age where condensing boilers were unusual and the boiler upgraded later, or the installer didn't do their calculations correctly. Bigger radiators allow the same heat output using a lower more efficient flow temperature.
In my locale the installer does just that. Install. Perhaps some calculation in order to sell you a bigger capacity, but certainly not optimization. Even talking about optimization with only high school physics with the people like installers and energy advisers gets you blank stares quickly. I think the benefits could be like 10% on your gas bill, but alas it’s untapped potential for those not into DIY.
Once you contact a slightly bigger company - say over 5 folks - you'll usually get one actually mastering their skill, for the initial talks. Then of course they'll send the lowlies to actually install and that's okay too.
This is outgoing flow temperature thermostat, adjusting the heating curve based on outside temperature. A very basic component which is on every single water based heating system in the Nordic countries. I am baffled why this is not a standard part.
This component can also adjust the flow rate and the temperature of the water. A more advanced system can look ahead the coming weather AND price of energy and use thermal capacity to overheat / cool the building ahead of time.
In large parts of the US it rarely gets much below freezing. I'm not even _that_ far south (35 degrees N lat), and the coldest month of the year has an average daily low of 0.5C. Coldest temp ever recorded here was -20.
> If you're using gas or resistive heating anyway this achieves very little.
? This isn't correct. If my kettle boils in 2 minutes when it's half full, and 3.5 minutes when it's full, then by only half filling it you are saving 1.5 minutes worth of (gas/electricity). Low absolute impact, but high relative impact, and adds up if you boil the kettle 3+ times a day
If you're using resistive heating then you're just heating the house with a different resistor.
If you're using gas, it depends on how your electricity is generated and how much heat escapes through your boiler's exhaust etc (some very old boilers are less efficient than a gas turbine + transmission losses).
> That's assuming you're only drinking tea when you want the heating on though.
Yeah, I meant using in the present tense, sorry (ie. The system is keeping the room above ambient even if it's presently idle due to the thermostat). If you're cooling the space, it's much worse.
> Plus you seemed to have gone on the boilers rather than kettles.
The boiler would be the gas central heating system. The kettle is making the tea.
My house doesn't need heating from April to October. And if you have a modern condensing gas boiler it is considerably more efficient (over 90%) to burn gas in it than use electricity generated in even the most modern and efficient gas fired power station.
So unless you have some quite specific circumstances it is almost always better to boil only as much water as you need at the time.
> And if you have a modern condensing gas boiler it is considerably more efficient (over 90%) to burn gas in it than use electricity generated in even the most modern and efficient gas fired power station.
If your grid is low carbon it might still break even (it will cost you money though).
This is all relatively pointless minuitae though. The main advantage is it's faster so one should do it anyway as there's no downside.
Unrelated, I've always been fascinated by the idea of a solid state heat engine driven kettle. Peltiers are so inefficient that it's not really pointful even as a toy though. I keep waiting for magnetothermal to be a thing.
That's using 50£/MWh, which sounds like an inaccurate wholesale price to me. With a quick search, I'm seeing the average rate in 2022 around £0.225/kWh, or 4.5x your rate. 5 kettles a day sounds right for my household, and would be £31.5/yr
yes. except it seems to be hard to get a kettle that will do less than 2 cups. ive got a phillips one that does one cup. id like one where it actually turns off at say 90c rather than boiling for x seconds. there are a few that do that, last i looked though they were 2 cup minimums
I have a docker instance of it running on an Ubuntu server at home, and I bougth a few pre-flashed Tasmota electricity meter plugs from Delock. I added another docker container for mosquitto (MQTT) which reads the plugs and integrates into HA. This way I learnt my NAS eats as much electricity a day, as does playing Horizon Zero Dawn on my PC for an hour. Ikea Smart lights on half the brighness are basically non-consuming, and the router is best kept shut down when we're not home for a week or two.
In the end, small household appliances don't make as big a difference, as letting your car charge with solar when electricity is cheap, and reducing charge speed when electricity is expensive (which is also doable with HA). There were great threads in HN about how you can even save energy by heating up or cooling down your house in advance with cheap electricity during the day when demand is low, and turn down the heat/ac in the night when demand is high, thus storing energy in the form of heat. But as a junior programmer with a wife in an already expensive apartment, small savings add up. We realized that running the washing machine less often but fully loaded, and with the lowest temperature water, saves us approximately the cost of Netflix. Few people know it's even fine to wash clothes with cold water.
Ultimately though, our apartment is pretty well insulated, and I would do all the home automation that I have just for the fun of learning. I definitely spent more money (and time) on the server and smart things than what they save us in our bills. Although I hope to apply my knowledge soon at my parents' house, where there's a lot more potential in energy savings.
Worth noting that Home Assistant OS + the official and community add-ons make managing all this very easy.
I haven't used it long, since I just moved over from a docker-compose based installation; but, it seems like it makes managing docker-compose files a thing of the past. I'm thrilled b/c the main reason I'm even messing with HA is to set up some automation for a non-developer friend.
I have a server running over 50 various docker containers, and only 2 virtual machines. One of those VMs is Home Assistant.
I tried the container originally, but the full OS is just a better experience. It handles all the supervisor stuff a lot better, and there’s tons of addons you can install with one click. I even have VS Code embedded in my HA dashboard so I can modify my config directly from my web browser.
If anyone is looking at trying HA, I’d recommend starting there (https://hass.io).
Using HomeAssistant OS here, with the new energy dashboard. I used an ESP32 device running ESPHome to read the flashing LED on my meter and send energy use to HA. It reacts faster than the zigbee monitor that came with the meter to give me good real time usage and long term stats. The energy use over time allowed me to spot some areas where I could reduce consumption.
Your NAS's bios power settings almost certainly need tweaking to reflect the current state of energy prices. I did with my Intel NUC and got my 24/7 power usage down 40% with no noticeable performance impact.
From memory it was CPU power settings down from max performance to balanced, and I turned turbo boost off. The former lowers the idle wattage and the latter lowers the peak. 8th gen i7 now idles at 8W, which is pretty decent for 24/7.
It's just a Plex server and has x265 hw decoding so there's really no reason for it to be tuned for high CPU performance.
I use it, pip-installed because it's distribution model, a whole OS just to deploy a web-app, it's honestly obscene... It's WebUI is slick, it design less horrific than anything else I tried, but still horrific. To arrive to something maintainable in the YAML monstrous config I've use org-mode.
And that's rant is just the tip of the iceberg:
- finding device who talk ModBUS or MQTT depending on their kind (i.e. if they need fast monitoring or not) it's HARD, most non-industrial commercial stuff are cloud-IoT crap;
- finding devices built for renewable is essentially impossible: those who claim are designed to are not, the others are equally not. It seems that most OEMs or consider that most do not have p.v. etc so it's not worth investing in that area or their very designers do not have p.v. etc and have very wrong assumptions about it.
A small example: I have one of the "most advanced" "modern" water heater, "ready for renewables" etc, a 300 liters boiler where the water can be heated:
- with a small heat-pump
- with a classic resistance
- with something else, an external source like thermal solar, a hydro stove etc
"modern" for it means:
- instead of heat directly sanitary water it heat a "storage water" and have a long metallic spiral where the sanitary water enter from a pipe and exit heated, a good thing for health and durability (the balloon is not pressurized, so cracks are far more unlikely) but that's is. Just a different design with classic decades old tools, nothing special for renewables, energy savings etc.
- it's better insulated than classic water heater, again a good thing, but it's just a thicker wall of insulated material...
- it allow hot water from external source, again nothing special, heat exchanger like that have invented decades ago.
- ...now the "new, smart, exiting part": it offer two switch, one for classic "cheap energy vs expensive energy" and another to be used as a second bit of the first to state: "do not heat, very expensive energy", "do what you want", "energy mildly cheap, start with the heat-pump only than go with the resistence)", "very cheap energy run both heat-pump and the resistence". They do not even consider adding an option to run heat-pump only than stop when it can't heat more or resistence only if you have enough for it (2.7kW) but NOT ENOUGH for it and heat-pump together. Those who design it never consider the direct self-consumption usage, the SOLE sound renewable usage. And that's "designed for renewables".
Now the best: from the lowest segment appliances featuring cloud-tied crapplications, with useless features but NOTHING usable locally, not even dry contacts to being controlled by a homeserver to the highest segment like smart wall box for EV recharge where only VERY few offer basic logic like:
- charge ONLY from renewables
- charge from renewables but watch the clock, ensure this minimum SOC for $this_time seeing actual renewable power and local grid maximum power
- charge as fast as possible
- slow charge targeting $SOC for $this_time
ONLY few months ago a new CCS standard appear dealing with bi-directional usage to enable V2H applications, of course NO ONE have implemented it so far even if EVs are there since decades, albeit marginal. Most EVs use 400V DC batteries, most solar inverters support domestic high voltage batteries who happen to be equally 400V DC, with the very same BMS and concept than cars batteries but no, you can't just plug the battery-on-wheel like the stationary one even if they are the same, nobody though at that so far apparently.
At automation level? NEARLY ALL "smart" stuff are unreliable wireless devices with various radio tech/protocols only VERY FEW are wired even if from simple ModBUS to powerline and equally complex TCP/IP stack with classic ethernet cost the very same and happen to be far more...
Seems like a no-brainer once you think about it ... in the worst case of a flow heater you bring up the water to temperature, let it flow over your body and dump it with most of the heat you put into it.
Systems like the one liked above improve on that by recovering some of the energy. I don't know what the "official" way of installing this system is, but I would just put it in the cold water path and have a thermostat controlled faucet to "switch" to the now-warmer-water gradually.
Do you even need a switch? In a normal cosed system (so no additional storage etc, but even then it's usually closed I think), cold water is fetched by the boiler to replenish the hot water which goes out when you're taking a shower. Small amount of time later the drain gets warmer, so it starts heating the copper tubes, through which the incoming water is flowing hence that gets warmer. And hence less work to do by the boiler.
I think it depends on the details of the install, if you can install it directly in line of the cold line input and the boiler, I think that works fine.
But I think instead often the heat recovery is installed somewhere in-line after the boiler, to make piping easier, but it makes heat management obviously more complicated.
A mixture of hairs and fat going through a heat exchanger doesn't sound like low maintenance. Luke warm water remaining in the exchanger after a shower feels like a great way to cultivate bacteria, though on frequent use that's probably no issue.
Tapping the waste water as heat source for a heat pump seems like a better idea.
If the heat is already higher temperature than the target environment, then a heat pump is just a fancy resistor. Plus this doesn't obviate the need for a heat exchanger.
Better to just have a filter on the drain similar to a dishwasher.
Is it a fancy resistor? If you have a cop above 1, you're extracting more energy than could be got just using straight heat exchanger. I don't see why that would break just because you go above an arbitrary temperature (arbitrary because the output temp of the heat pump isn't the ambient temperature of the room)
The heat is conserved. If the waste water is hotter than the incoming water it will conduct on its own (and if they're arranged in back flow the equilibrium will be pretty close). Hurrying it up with a heat pump only makes it happen faster and adds the energy you put into the heat pump. You could cool the waste below ambient, but that's no different to cooling anything else outside.
For simplicity, if your hot water system was already a heat pump, you could run it past/into the cold side. No real efficiency gain vs exchanging it with the cold water (actually a loss in theory) but might be cheaper.
Ok I've worked it out myself. I was inventing a magic free energy machine.
I was thinking a cop of 4 would be able to extract 4 units of energy to the heat exchangers 1. But there's only 1 unit of energy in it to extract, which the heat exchanger is already extracting basically for free.
No, the source is the waste water, the target is the fresh water.
You could either use a heat pump to move the heat from the colder waste water to the hotter fresh water, or use a direct heat exchanger to pre-heat the freshwater while chilling the waste water down, to then put a resistance heater between the heat exchanger's freshwater outlet and the shower head's input.
But it should be more efficient to run a heat pump against the heat exchanger's inefficiency/delta then to let it happen and compensate with an ohmic heater.
Yes, the wastewater discharge with a 100% efficient heat pump might actually leave colder than the fresh water comes, due to heat loss to the room exceeding the work required to pump the heat against the exchanger's losses.
Ambient temperature water is entering the system somewhere. You'd put your heat exchanger there.
The replacement for the lost heat would happen to the equilibriated water and could happen with a heat pump. In principle (if your heat pump and exchanger is perfect) this generates no entropy so is more efficient than putting things with finite temperature delta in contact. In practise it's probably just simpler and requires a smaller heat pump.
Whether you use the waste water (which will still be a degree or two above as exchangers aren't perfect) or whatever your normal source is (ground source may be warmer) would be about cost and making the heat pump work for not-the-shower too.
Typically the drain pipe for such heat exchangers is a normal drain pipe — large diameter, no kinks, etc. — and made out of copper. A larger pipe surrounds it, bushings and T sections at either end of the segment. Cold water flows into one T section, flows around the drain pipe and extracts heat, then out the other T and into the cold water input of the hot water heater. There are a million YouTube videos on how to make one, and there are now readymade commercial products to buy, too. The tricks are getting at your shower drain and getting the cold water input piped over to it.
I get the desire to do stuff like this but the numbers never work out. Wrapping a large diameter drain pipe with copper is hella expensive and a terrible heat exchanger. It would take a century to recover the cost of the copper plus installation. Also It's best not to screw around with waste water. You want that stuff to get to where it needs to go. There are enough problems with it even when you're not messing around and even one backup during the its lifetime would easily cause enough damage to offer the entire thing.
Check out the link posted. It's a pretty clever solution that wouldn't require any more maintenance than a typical drain. It would be not nearly as efficient as a typical heat exchange, but would also be low maintenance.
I figured that the most sensible way to install theses is in the cold water path directly in the shower. That way (part of) the heat is recirculated in the shower. The savings then come from having to run less hot water and thereby having to spend less on water heating. This works even if you have a central store of hot water (as I think is more common in modern European homes these days).
I'm always amazed at how people in the US/Canada shower, with the water running constantly. It not only seems like a waste of hot water, but how do you even soap yourself up when the water is just washing everything away immediately?
Where I'm from, we take Navy showers[1], where you only use water to rinse things off. Basically:
1. Run water on you so you get wet everywhere, turn the faucet off.
2. Apply body wash and shampoo.
3. Turn the faucet on and rinse everything.
4. Done.
The actual water-using portion of this is less than a minute.
Gas boilers with long pipes means you need to wait for the hot water to come through, and if you stop it again you then have a load of cold water just waiting to take you by surprise.
It only takes you by surprise once in your life, after that you just run the water away from you for a second while the warm water comes in. Since we have handheld shower heads (another thing I can't believe the US lacks), it's no problem at all.
No but the boiler takes time to come on so at some point it's going to run cold because cold water is flowing through the pipe before the boiler turns on.
I suppose you could time when the cold water is going to arrive an step out of the shower for it to flow through, but my point still stands, it's a pain and just easier to leave the shower on.
That sounds much more efficient, but it also sounds like a great way to freeze in the middle, when you're all wet but don't have hot water to warm you back up. Maybe in warmer climates?
How does this work if you're only using water for a minute, per your original comment? Does it generate enough steam to keep you warm for the few minutes of waterlessness?
Yeah, the shower cabin/curtained bathtub is a fairly small space, so you don't need the entire bathroom to steam up. It's comfortable for many minutes afterwards.
Interesting, maybe I'll try this in my smaller shower. My challenge is that (1) we have a low-flow showerhead, so there's not much coming out even when it's on, and (2) our showers are far from the water heater, so it's the least-hot receptacle in the house. We set our water heater temperature pretty low, and by the time it gets to the shower it's less hot and not so steamy. I wish there were a unit we could attach right at the nozzle that would give it a little boost!
Try it the next time you shower, and see for yourself :).
Even a minute of initial water flow should generate enough heat in the enclosed area for the minute or three you need to comfortably apply whatever gels, soaps and shampoos you need. If that's not the case, then either you're in a place with harsh winters and it's the coldest week of the year, or your bathroom / building needs serious insulation rework. In that last case, I guess the water waste is a non-issue compared to overall heat waste due to poor insulation.
Also note that none of that precludes you taking your sweet time in hot water if you need it for e.g. relaxation reasons. It just doesn't make sense to keep it running for the part when you apply the cleaning agents.
You lean/step out of the water to apply stuff and then lean/step back in. Are your showers the size of coffins or something?
I get the efficiency of Navy Showers, but water is cheap where I'm at. Would be a lot of extra effort and discomfort for negligible savings. Maybe it makes sense if you live in a desert or, as the name implies, you're on a ship
> Are your showers the size of coffins or something?
No, we just don't like wasting water/heating. I don't know how much extra effort it is to turn the tap off when you're done with it. It definitely doesn't feel like effort to me, and having the water run while I'm trying to avoid it so I can soap myself up is very annoying.
> water is cheap where I'm at.
You are in a thread where people are installing heat pumps to reclaim the wasted heat. Is saying "how about you don't waste the heat in the first place" really that crazy?
If it's a micro-optimization that produces no real value, then perhaps it isn't crazy, but is irrational if the goal is to save meaningful amounts of money.
You can also compress/save used aluminum cans and periodically sell them to a scrap metal dealership for money. Quick check shows scrap aluminum cans are selling for a national average of $0.45/lb, and it takes about 32-35 12 oz cans to accrue 1 lb of aluminum cans. Assuming you go through a 24 pack of cans per week, enjoy your ~$1.30/month savings for hours of effort!
Yeah, well, to the millions of people for whom that's just "how one showers", your way seems needlessly wasteful, like heaping food on your plate only to throw most of it away.
I remember the push for showers over bathtubs to be based on the argument that they're X% more water-efficient. I would imagine this refers to "Navy"[0] style, as not turning off the shower for the entire duration will easily waste a few bathtubs' worth of water.
How cheap is water in your place you'd consider this a micro-optimization? In my country, unless you're tech-salary-equivalent-or-above, not doing it - and doubling or tripling your hot water (or water + gas) bill - would noticeably cut into whatever discretionary spending money you have.
Micro-optimization would be "grey water reclamation" with a bucket placed in a sink, to reuse hand-washing water for flushing the toilet. Which is something my wife and I started to do a while ago, and while we don't need to do it, the drop in utility bills for near-zero effort is impressive enough that we continue anyway.
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[0] - Or should I say "Standard Showers", as I literally can't think of anyone who doesn't turn off the water for soaping after being made aware that water and heating both cost money.
I'm in Philadelphia, PA, USA. It's a convoluted formula based on your type of sewer hookup (https://water.phila.gov/pool/files/rates-and-charges-2022-09...) and there are different tiers of usage, but the initial base rate is $48.96 for the first 1,000 cubic feet of water or 7,480 gallons, so about $0.0065/gallon + sewer cost. A "typical" household in the city (they estimate 500 cubic feet of water usage) is apparently around $70/month total. We typically come in under that at around $60. My gas bill runs about the same in non-winter months, but most of that is the clothes dryer and oven/range.
So it's not a negligible amount of money, but it costs less than my combined streaming services. Cutting it by 20% would allow me to afford... another streaming service? A couple of days' groceries?
I'm also not sure what kind of showers you're taking, but I know from experience being forced to shower with a mostly-clogged drain for a couple of days there's no way my shower head is filling the tub even over my ankles before the shower is done (5-10 minutes). So "several bath tubs" is an exaggeration unless you're taking extremely long showers or your showerhead has the efficiency of a fire hydrant.
And I guess we're just blessed with plentiful water on the US East Coast, because I've lived in several states on this coast for my entire life and I'd never even heard of "Navy Shower" until college, and only then as a reference to... the Navy! Or sometimes we hear about Californians being asked to do so when a drought hits.
But whatever, you do you! If it actually does make a difference for you than go for it!
> So it's not a negligible amount of money, but it costs less than my combined streaming services. Cutting it by 20% would allow me to afford... another streaming service? A couple of days' groceries?
Your math comes out similar to what I remember from the utility bill (which I currently don't have handy, so I won't provide exact calculation). It's not life-changing, but it's not nothing. A couple days of groceries worth of money we could use for arbitrary discretionary spending, at a cost of... pretty much nothing, I don't consider this habit to take noticeable effort over keeping the shower running. And with several more such "little to no effort saves you a Netflix subscription" habits, this adds up. You can probably ignore $100-$150 / month saved off utility bills and incidental costs when on a tech-equivalent salary, but many people wouldn't.
(And yes, we mind the opportunity costs too.)
> I know from experience being forced to shower with a mostly-clogged drain for a couple of days there's no way my shower head is filling the tub even over my ankles before the shower is done (5-10 minutes).
That's an interesting data point. I may have exaggerated with "several tubs", though my actual shower, left on for the entire duration and with drain plugged, would fill a tub[0] to the level where, were I to lie down, the water would spill out[1]. We may have different sizes of the tub/showering compartments, and possibly different pressure levels and flow rates. Eyeballing it now, the bathroom faucet gives some 10-12 liters per minute, maybe a bit more; this is cut down to some 8 liters per minute when going through the shower head in default setting.
> And I guess we're just blessed with plentiful water on the US East Coast, because I've lived in several states on this coast for my entire life and I'd never even heard of "Navy Shower" until college, and only then as a reference to... the Navy! Or sometimes we hear about Californians being asked to do so when a drought hits.
I never heard it called this way until 'stavros mentioned it today! For me, it was always known as the "mom asking 'why are you wasting water in the shower?' shower" :). We don't need to do it, it just feels unnecessarily wasteful if we don't (and it makes noticeable difference in the bills for households on median salary or below).
[1] - I admit I got confused by my intuition. A "standard bathtub" similar to [0] will hold over 200 liters of water, which is of course way more than the shower head would provide over the duration of my shower. When I wrote about filling bath tubs, I thought intuitively about the volume past which you can't lie down without it spilling out.
Well it wouldn't save $100-150 / month, that would be my entire water and gas bill outside of winter. Digging a little deeper, according to the EPA a standard shower head delivers 2.5 gallons/minute (https://www.epa.gov/watersense/showerheads).
So over the course of a 10 minute shower that's 25 gallons, * 0.0065/gallon = ~0.16/shower. Sometimes if I'm working from home and not exerting myself physically I won't shower (dry skin so I don't stink after just one day), so say an average 6 showers a week = ~24 showers a month = 3.84, and times 1.5 for the sewer cost (roughly) = $5.76 total / month from the water/sewer usage. Harder to calculate how much water heating costs since the same hot water source goes to all the fixtures/dishwasher/washing machine, and it needs to maintain temperature. But let's be generous and say 20% of the non-winter gas bill is strictly due to heating water for showers. So roughly $14. That's a total of $19.76. Let's say by doing, call them maximum-efficiency showers that take only 1.5 minutes of running water instead of 10. So an 85% reduction in costs would be $16.796 / month in savings. Again not nothing, but I'm not sure it's worth the discomfort either. Plus the steam helps with my shave a couple of days a week. I could also get most of the way there just by taking quicker showers, and honestly I'd rather do that. If I'm going to be uncomfortable, I'd rather have time discomfort than temperature discomfort :)
But yeah I guess it's also a cultural thing. And I'm sure there are some families over here that shower that way, I've just never encountered one in conversation/life. You certainly don't see it in gym/school locker room/dorm/pool showers, and in media, as you pointed out, people have the water running constantly.
No thanks, I'm not a poor animal struggling to survive during my brief existence on this world. I don't see why we should feel guilty as if we're wasting something. All that water goes back to the environment, hopefully through your garden instead of municipal sewage, and for those really self-conscious about energy use, most of the heat to make that shower water warm was renewable.
Municipal sewage is one of the main things we need to focus on atm. We essentially mix black water with grey water, turning the whole concoction into black water that needs to go through sewage treatment. Woohoo, government screwed us over yet again.
Instead, we should re-use grey water in the garden or at least have a separate municipal dump for grey water.
> , and for those really self-conscious about energy use, most of the heat to make that shower water warm was renewable.
That's highly dependent on location and time. And even if it's renewable, it isn't necessarily cheap, and the people in this article are mostly motivated by high energy prices, not renewability.
The cost of repiping every house and having a separate sewer system makes that highly impractical and why basically nowhere has done grey water usage on a large scale. It's mostly relegated to single home or personal use because of that, you need a system designed from the ground up to handle grey black separation.
Is it still wasteful if I enjoy taking hot showers? There might be some health benefits too, but I also just enjoy them as part of waking up in terms of loosening up my chest and relaxing muscles.
My total yearly spend on showers is about $100 a year, and there's lot of things I'd give up before that to save $100, in dollar or energy use terms.
I can't do this - it takes me several minutes to adjust the shower water temperature to the correct temperature after turning it off. (The difference between boiling and freezing is like 1 degree of rotation, I'm only slightly exaggerating.)
Eventually I'll get a new valve, but right now changing the water flow also changes the temperature.
I looked into these things a long time ago and part of the problem is that the drains will build up a layer of biofilm (bacteria, soap scum, other waste) on the interior, making the heat exchanger lose efficiency over time.
In vanlife some people have built recirculating showers that use just a few gallons of water running in a loop. They run it through particle and UV filters which supposedly clean the bad stuff out, but I haven't seen any scientific studies done on how effective that is. I imagine it is no worse than a bath, other than you are potentially putting bacteria into the air and hence your lungs. The idea sounds interesting though, as showers (even low flow) use a lot of water and heat, which typically just goes down the drain.
I couldn't find setting flow temp in 2.2 (only reading) but I only skimmed it.
Edit Although to be fair it's way more open than something like EMS, which is what my Worcester Bosch uses. There's some info on that from reverse engineering efforts but that's it.
If I was buying a new boiler I'd try and get one with Opentherm support for future proofing. Surely more controllers will come out. Isn't much at the moment AFAIK.
Yeah I also have a Worcester Bosch one and always was disappointed that it didn't support OpenTherm but it turns out they make a £40 adapter to convert EMS to OpenTherm! I've ordered it. We'll see.
Looks like the "Control setpoint" is the relevant command for flow temperature.
I don't get it. How does this improve on the outside temperature sensor that comes with every heating system? Or is that not standard in the UK? Here in Germany it has been a standard feature for – well as long as I can think (several decades)...
I've never had this in the UK, even with fairly new ones. Looking at the models offered there doesn't seem to be any mentione of a feature like that, even on the higher end models.
My parents got the highest-tech HVAC system locally available (rural midwest USA, "Lennox iComfort") five years ago, and rather than external temperature sensing it requires an internet connection so that it can talk to a weather service. Seemed sort of Rube Goldberg to me, but it seems to work?
Most of these Worcester (Bosch) boilers don't come with these sensors. The one installed by my landlord is so cheap it doesn't offer any regulation interface besides the one knob in the front. It also lacks any temperature display, so I had to tune it with external thermocouple.
Usually the boilers are also oversized for houses here. The temperature differential is not big enough and you waste quite a lot of energy through steam.
Finally, the system boilers are also the most common (as opposed to combi-boilers) and for that reason you are not supposed set them below 60 degrees.
The other day I had a conversation with an expat colleague about the UK building "standards". Most of what we consider in Europe as table stakes is unfortunately unheard of in the UK.
Building insulation for one was a shocking factor. It's 2022 and stuff that was considered "normal" in Europe 10 years ago is still a problem in a lot of UK buildings. Worse, it doesn't even require rebuilding - you can improve the situation incrementally, so it should be a no-brainer for a government to subsidize, yet they aren't doing so.
I've lived in social housing in France that was much better insulated (it would be considered "good" even by today's standards) than places here that rent privately for 2k+/month.
Pretty nice for a DIY project, but it turns out that the first guy in the article uses an Alpha e-tec boiler, for which the manufacturer also sells a "weather compensation probe" to adjust the heat output according to outside temperature.
It's just under £45.
Why would you want a weather compensation probe? Surely it's indoor temperature that matters.
Is it for heat pumps that work slower? It still implies to me that insulation is lacking.
I'm still somewhat dubious of 'better' thermostats though. I just turn it on when I feel cold. I don't see how a thermostat could improve on: 'The heat only goes on when it's cold enough for me to turn it on'.
I'm guessing it adjusts the boiler quicker (up/down/off) than simply by measuring indoor temperature, which is a lagging indicator.
I can also bet that insulation is very much deficient, this being the UK.
Wouldn't insulation be the first thing to fix though?
I've got cavity wall insulation, 30cm of insulation in the loft and recentish double glazed windows and the bedrooms stay warm enough at night with just body heat and residual heat. The heating on goes on in the evenings (still hasn't gone on yet) unless it's really cold. I don't think any of those are particularly onorous jobs to undertake.
Yes, I'd say you are absolutely right in that insulation is the most important thing to improve. I'm not familiar with cavity insulation, but I suspect that it's not the best in terms of efficiency. On the other hand different kinds of wall insulation might ruin one's health or one's house, so I'm not really sure what can be done (if anything).
My house has something called ETICS* (basically a thick outer layer of polystyrene with a weather resistant paint. Ugly stuff, but it works wonders!), mineral wool insulation in the attic (which I'm supplementing just in case), underfloor insulation with extruded polystyrene and of course double glazed windows. We don't turn on the heat until it's 3 degrees or less outside. Thermostats and stuff like in the article bring too small benefits to really consider.
I've half looked into external insulation. I don't think the roof overhang is enough though. So I'm not sure it's worth it as the roof would need sorting too.
Ultimately my direct debit for gas electricity is only £10pm at the mo after the govt bung so my house is about as good as I'm going to get it anyway.
For sure, but it doesn't cost £15 to fix your insulation.
For those of us with solid walls it's expensive and very disruptive to install internal/external wall cladding. I happen to live in an area where I'm not even allowed to install external cladding.
Insulation is great. But if you rent then you have limited control over what you can do. Insulation seems to be hard for Renters but maybe turning up and down a boiler is possible.
Well, outdoor temperature determines the heat load demanded of the radiators, and lower exhaust temperatures for a condensing boiler mean more condensing takes place.
So unless/until the circulation pump starts to dominate, one wants to run the water in the heating loop towards the radiators as cold as will still suffice (though cold here is more important for heat pumps; the boiler cares more about how cold the water leaves the radiator), and often have a rather small temperature delta between the inlet/outlet ports of the radiator loop heat exchanger in the boiler.
Theoretically it could use feedback from all the thermostat valves (and adjust the burner to keep the most-open valve near (but not at) 100% flow), but that requires feedback from all valves rather than just an outdoor temperature probe and a parametric mapping curve that depends on radiator style, desired indoor temperature, and building insulation.
It's a modulating boiler, it's not on/off, rather it has levels.
The lower the level the more efficient it is. It's better to run the boiler on low for 3 hours, vs high for 1 hours.
How do you know if to run the boiler on low or high? You check the outdoor temperature. You also do a backup: If the boiler has been running for more than an hour, increase the temperature slightly every 15 minutes. Once it goes off, reset the temperature to the one determined by outdoor temperature.
The way my house is set up, I doubt it would be dramatic for me. My hot water is already turned down. It seems like a big project to install a heat exchanger given the space it would need to be in.
Well there's no silver bullets. If you're on HN you're probably more engineering inclined than 90% of the population anyway and could figure most of the big stuff out.
These types of articles are for the general population which may not realise things about insulation. Or energy, or phase changes etc. And generally sent interested in how things work, or efficiency, except to the extent it costs them money.
Basically none of us hackers out there saving 10-20% on this and that is going to make a difference whatsoever. It might make us feel good I guess.
What would help is higher regulatory energy standards and better enforcement. I’d settle for making sure builders actually use insulation and don’t leave obvious thermal bypass/bridging across it.
My 20 year old new build property leaks heat due to it being a “plasterboard tent” (thermal bypass due to missing sealing around dot-and-dab drywall). If a building inspector had actually checked this before signing it off, it’d have been rejected.
Yes but the point is you realise all this. And if it was important enough to you (v cost) then you would sort it. Most people wouldn't be interested at all.
Yes regulation and other stuff is sorely needed. But in the context of what an individual can do 10%-20% is nothing to be sniffed at. And I suspect that severely underestimates the savings compared to the average person, let alone the worst offenders.
> But in the context of what an individual can do 10%-20% is nothing to be sniffed at.
If collectively it means 0.00000001% change I don't find it provides much "I did a good thing" value and the time would have been better spent fundraising, petitioning politicians, or maybe even just raising awareness towards say... improving a law that makes a collective 1% difference.
The best "trick" is to vote. Either with your actual vote if you're eligible, or with your wallet, by moving out of a failed state and thus no longer paying taxes towards it.
IME, the most useful way to keep your energy usage down is to get an energy monitor. Almost akin to seeing how fast your electricity meter spins, it's enlightening to see how much money you're spending per hour/day/month in real time.
Yes ! I have found a couple of constant ~100W loads (faulty fridge, broken hot water sensor causing constant pumping) that were costing hundreds of pounds a year.
My utility recently made smart-meter metrics available (even raw data feeds) with 15min resolution for all energy use and pricing. It's been incredibly helpful, however my biggest electricity hog is my refrigerator.
However, the hardest thing to do when figuring out what uses / wastes electricity in your home is establishing a baseline with the most appliances / systems turned off as possible.
My apt is well insulated, but for me it's still crazy (even packing the fridge with as much thermal mass as possible), and furnace / AC turned off at the breaker my apt still uses around 8KWH per day. Water heaters and refrigerators have a long way to go! Curiously, leaving my AC / furnace completely off or on at about 80% cooling a 20F delta uses very little power, exciting how efficient modern climate control is :).
I’ve had to fool the ecobee into thinking I have a heat pump (I guess I do technically) just to avoid it turning on the aircon when it’s below 18.6C outside.
I think it’s called the heat pump lockout setting or something.
But I can’t set the threshold higher than that, so I still end up in situations where it’s 20C outside and the AC is on to get it under 23C when really I should get the cue to open windows.
What ends up being ok for me in my apartment is an inexpensive 'dumb' space heater on a wifi plug and a room fan with a temperature sensor I made with an ESP32 on it all tied into home assistant to be a 'smart' thermostat. I have baseboard heating and its set up terrible in this apartment.
Good call, I've had these Sonoff plugs run at 1000w for several days before (a big dehumidifier that maintenance put in to dry out a leak), but at "high" setting on the fan the inrush current goes to 15A, at medium the inrush is 7A and stable at 6.
I have a warm water boiler / water heater where I live now. Running fully on electricity, which I have 'made smart' with Home Assistant. First of all I replaced the analog temperature sensor with a digital DS18B20 connected to a Raspberry Pi. I 'calibrated' this sensor with another sensor at our main faucet in the kitchen, so I can set the tap water temperature. Secondly I've added a power monitoring smart socket to the water heater, so I can switch it remotely. Finally I've added both to Home Assistant as a climate device, so I can easily control it.
Simply put I've set it up that during electricity peak times the boiler doesn't try to heat water to save on electricity costs. Heating water is all done in the off peak hours with some easy calculations. Also I tend to set my boiler to a lower temperature (ie. 58 degrees) during weekdays and higher (60+) during weekends or holidays. That way I always have hot water and get rid of legionella growth.
What I can see I'm using about 1.5 - 2kWh a day for keep 100 liters of water at at least 55 degrees. While the manufacturer of the water heater says the device should use between 7 and 9kWh a day. I really would like to optimize it any further, but it seems that I've hit a wall.
If you're in the US. Starting next year, the Inflation Reduction Act added a $1900 tax credit for purchasing heat pump water heaters so it might pay off earlier than you think.
Yes. I know of these. Here in the Netherlands those start at about 1000 euro's for a hybrid solution. A full heat pump boiler starts at about 2000 euro's. But you get about 600 euro's subsidy. However, as far as I can tell it will only about half my power consumption for hot water. So with the current electricity prices (about 30ct/kWh) it will pay back itself in about 13 to 15 years or so.
I've also looked at instantaneous water heaters, which could be even more efficient. But those with enough capacity need 400V, which I don't have in my apartment. Also I would probably have legionella growth in my regular water heater if I want to save even more electricity. Which would be a health issue.
One additional data point: on my heat pump the economy setting for hot water production starts heating once water cools to ~42C (truly, a universal answer) and heats it up to ~55C.
As for anti-legionella, once a week there's a cycle where the top setpoint is raised to 65C.
I recently just set up a smart plug I got at LIDL for about €8 to turn on only for the 6 cheapest hours per day. Here in Spain the prices change per hour seemingly randomly but they give 24 hours notice. It was pretty easy to do in about 5 lines of YAML in Home Assistant that hits a JSON api with the prices. I use it to charge my electric scooter and battery banks. Remains to be seen if running a Pi with Home Assistant 24/7 actually would save any money overall, but I am already running it for a Pi Hole instance.
The best "gadget" for saving energy is a sweater. Conserve your own body heat and turn down (or off) the furnace. If you're concerned about your energy bill and you're also wearing tshirts indoors in winter, you're doing it wrong. Get long sleeve shirts, put on two or three layers, get some warm clothing like sweaters and thick wool socks. Then turn your furnace down to 10 C / 50 F. I promise you will survive. Your pipes won't freeze. With warm clothing, you will even be comfortable.
That happens when the cold walls are cooling down warm air, dropping the moisture out of that air. If you have a warm house and open all the windows in winter, you'll get condensation on the walls. If the house was cold in the first place, e.g. the walls and air are in a cold thermal equilibrium, you won't get condensation on the walls.
Bathrooms and kitchens are a special case, which can be addressed with ventilation. One of the upsides of keeping your home cool in the winter is it's much cheaper to circulate in new air from outside. You get to have fresh air all winter without paying to heat all that air up. I believe fresh air throughout the year has many health benefits.
It really depends. The air that you exhale is hot and humid. As soon as it touches the exterior walls, it will condensate. I'm talking about a house that is not insulated, but also does not leak air out (new windows with good seals). If it leaks some air out, then the condensation is very limited as outside cold air is dry in winter.
It might be like you said only if you don't use that room, or you have a big house so maybe you don't use most rooms and then you don't fill them with humidity from your own breath. Walls are cold but also dry.
Opening the windows in the winter is how you let all that humidity out.
In New England my dad always kept the house cold (not 50F) while my college dorm (also in New England) was kept toasty.
Going back and forth over winter break I definitely noticed a productivity shift being some place I was warm and comfortable.
Perhaps there are less noticeable psychology benefits for it being cold but I do not think being uncomfortable and dealing with it is a long term strategy for success. And probably completely impractical if you live with other people in the same house.
When your core cools, your body will react by reducing bloodflow to your hands and feet (which are basically radiators) to preserve heat for your core. Generally, dressing warm to keep your core warm should help keep your hands and feet warm too, but of course there will always be a temperature gradient.
If that isn't sufficient, there are still cheaper ways to deal with it than adjusting the furnace. A low power radiative space heater (the sort with a reflective dish) can be very efficient at heating up the person it's pointed at without heating up the whole room. Having a warm drink to pick up and sip on also helps; it'll warm your fingers directly and also give your core a little boost of heat. Heated electric blankets are also extremely effective.
Babies can't regulate their body temperatures well so no, they are not happy when cold. They are happy in the cold when properly dressed and warm, which I assume you meant.
The key point here with this napping thing that did the rounds is that this is just for short naps. People in Norway/Finland do not leave their babies in a cold environment for long periods of time. Presumably the main reason they do this cold outside nap is that it's easier to get a baby to fall asleep in a pram (safely wrapped up) but very disruptive to then bring it inside, where it will be warm, have to undress it and then inevitably wake it. But I don't know, there are probably also other reasons. But parents in nordic countries are the same as everyone else when it comes to heating their homes appropriately, especially for night time sleeping.
Personally I would imagine even things like eating would be harder if the room is too cold and the infant must always be maximally layered up. It doesn't need to be any harder.
As for guests, you can turn up the heat when guests come to stay and still see dramatic energy savings, vs running the heat full blast the whole winter.
You should be able to keep the piano’s humidity acceptable at lower temperatures with a whole house humidifier. Installation will pay for itself in a season if it lets you lower your thermostat several degrees. Some brands are more sensitive than others, of course.
Anyway, enjoy your... [checks thread]... bathtub waste water heat reclaimer. I'm sure that will make a big difference to your energy bill when your thermostat is turned up to 30C in January.
It's a bit extreme, but did you try Antarctica expedition suits? They're designed for minus 30c or below. Or just the top and one or two hiking overpants. Also mittens if you need your fingertips. Got myself some of that but it's not cold enough to try yet.
Sounds like what a modulating thermostat does. It will change the heat of the water flowing through the radiators based on the difference between current and desired temperature.
One big advantage over a on/off thermostat is that it the room temperature doesn’t fluctuate as much.
It should be considered a massive and laughable government failure for energy bills to have become enough of a concern to warrant a front-page article on national news.
These "tips" are good, but target the wrong market. Those who have the resources and/or knowledge to implement them are either already doing it, live in a well-insulated property, or make enough to not care about the bill in practice. Those who are actually affected badly by the recent energy crisis have neither the resources to implement these, nor will it make enough of a difference to their situation anyway.
The main problem here is that the government has completely failed its citizens by letting the situation get to a state where a significant proportion of the population is considered to be in "fuel poverty".
Blaming the Russia/Ukraine war is a convenient scapegoat but isn't the answer either. Being forever dependent on foreign energy is a major failure for the government, and even now, I'm not seeing anything being done about it. Most short-term energy subsidies won't address the problem (they may solve this problem, but won't prepare us for the next crisis - not to mention that personal energy subsidies do little when you still have to pay businesses' energy prices in the form of increased costs of goods).
There solutions IMO would be:
* massive subsidies on insulation. UK building standards are shocking by European standards, but the good thing about it is that incremental improvements are both possible (no need to demolish the building) and don't require scarce materials so no supply chain concerns there, merely money concerns the government can subsidize
* solar subsidies, and actually making feed-in tariffs competitive to encourage people to invest in it. This would reduce our energy dependency during the day (which conveniently is when the demand is the highest).
Government borrowing for the above points makes sense because it can and will be paid back down the line (solar lasts 10+ years and efficiency decreases gradually, so you'll get something out of it even 30 years later), unlike stupidly subsidizing people's energy bills without addressing the root cause which will be a one-off expense with no expected return.
1) giving them the benefit of the doubt, there might be rational reasons for it that I’m not aware of - unlikely but possible
2) a politician’s primary objective is to get re-elected and accepted/appreciated by their peers. They are usually rich enough to withstand whatever crisis is plaguing their country anyway, so they aren’t afraid of the consequences of their actions. Therefore, politicians probably benefit from what they do now more so that what they’d get if they actually enacted policies that benefit the common man at the expense of large companies and/or lobbyists.
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[ 4.2 ms ] story [ 339 ms ] threadhttps://www.repubblica.it/cronaca/2022/09/02/news/gas_pasta_...
My mother and mother in law both boil a full kettle regardless of how many teas they are making
? This isn't correct. If my kettle boils in 2 minutes when it's half full, and 3.5 minutes when it's full, then by only half filling it you are saving 1.5 minutes worth of (gas/electricity). Low absolute impact, but high relative impact, and adds up if you boil the kettle 3+ times a day
If you're using gas, it depends on how your electricity is generated and how much heat escapes through your boiler's exhaust etc (some very old boilers are less efficient than a gas turbine + transmission losses).
Plus you seemed to have gone on the boilers rather than kettles.
Yeah, I meant using in the present tense, sorry (ie. The system is keeping the room above ambient even if it's presently idle due to the thermostat). If you're cooling the space, it's much worse.
> Plus you seemed to have gone on the boilers rather than kettles.
The boiler would be the gas central heating system. The kettle is making the tea.
So unless you have some quite specific circumstances it is almost always better to boil only as much water as you need at the time.
If your grid is low carbon it might still break even (it will cost you money though).
This is all relatively pointless minuitae though. The main advantage is it's faster so one should do it anyway as there's no downside.
Unrelated, I've always been fascinated by the idea of a solid state heat engine driven kettle. Peltiers are so inefficient that it's not really pointful even as a toy though. I keep waiting for magnetothermal to be a thing.
https://www.wolframalpha.com/input?i2d=true&i=+3Divide%5BkW%...
I have a docker instance of it running on an Ubuntu server at home, and I bougth a few pre-flashed Tasmota electricity meter plugs from Delock. I added another docker container for mosquitto (MQTT) which reads the plugs and integrates into HA. This way I learnt my NAS eats as much electricity a day, as does playing Horizon Zero Dawn on my PC for an hour. Ikea Smart lights on half the brighness are basically non-consuming, and the router is best kept shut down when we're not home for a week or two.
In the end, small household appliances don't make as big a difference, as letting your car charge with solar when electricity is cheap, and reducing charge speed when electricity is expensive (which is also doable with HA). There were great threads in HN about how you can even save energy by heating up or cooling down your house in advance with cheap electricity during the day when demand is low, and turn down the heat/ac in the night when demand is high, thus storing energy in the form of heat. But as a junior programmer with a wife in an already expensive apartment, small savings add up. We realized that running the washing machine less often but fully loaded, and with the lowest temperature water, saves us approximately the cost of Netflix. Few people know it's even fine to wash clothes with cold water.
Ultimately though, our apartment is pretty well insulated, and I would do all the home automation that I have just for the fun of learning. I definitely spent more money (and time) on the server and smart things than what they save us in our bills. Although I hope to apply my knowledge soon at my parents' house, where there's a lot more potential in energy savings.
I haven't used it long, since I just moved over from a docker-compose based installation; but, it seems like it makes managing docker-compose files a thing of the past. I'm thrilled b/c the main reason I'm even messing with HA is to set up some automation for a non-developer friend.
I tried the container originally, but the full OS is just a better experience. It handles all the supervisor stuff a lot better, and there’s tons of addons you can install with one click. I even have VS Code embedded in my HA dashboard so I can modify my config directly from my web browser.
If anyone is looking at trying HA, I’d recommend starting there (https://hass.io).
I agree it's way better than the docker approach, especially once you start adding USB things that need to be piped in.
I had a tough time trying to get my Aeotec Gen5 Zstick to passthrough.
I'd love to know what your setup is, since it sounds like you've been successful in connecting USB devices to HA. Thanks in advance!
Plugged the devices in, added them to the VM from the UI and never had any issues.
It's just a Plex server and has x265 hw decoding so there's really no reason for it to be tuned for high CPU performance.
And that's rant is just the tip of the iceberg:
- finding device who talk ModBUS or MQTT depending on their kind (i.e. if they need fast monitoring or not) it's HARD, most non-industrial commercial stuff are cloud-IoT crap;
- finding devices built for renewable is essentially impossible: those who claim are designed to are not, the others are equally not. It seems that most OEMs or consider that most do not have p.v. etc so it's not worth investing in that area or their very designers do not have p.v. etc and have very wrong assumptions about it.
A small example: I have one of the "most advanced" "modern" water heater, "ready for renewables" etc, a 300 liters boiler where the water can be heated:
- with a small heat-pump
- with a classic resistance
- with something else, an external source like thermal solar, a hydro stove etc
"modern" for it means:
- instead of heat directly sanitary water it heat a "storage water" and have a long metallic spiral where the sanitary water enter from a pipe and exit heated, a good thing for health and durability (the balloon is not pressurized, so cracks are far more unlikely) but that's is. Just a different design with classic decades old tools, nothing special for renewables, energy savings etc.
- it's better insulated than classic water heater, again a good thing, but it's just a thicker wall of insulated material...
- it allow hot water from external source, again nothing special, heat exchanger like that have invented decades ago.
- ...now the "new, smart, exiting part": it offer two switch, one for classic "cheap energy vs expensive energy" and another to be used as a second bit of the first to state: "do not heat, very expensive energy", "do what you want", "energy mildly cheap, start with the heat-pump only than go with the resistence)", "very cheap energy run both heat-pump and the resistence". They do not even consider adding an option to run heat-pump only than stop when it can't heat more or resistence only if you have enough for it (2.7kW) but NOT ENOUGH for it and heat-pump together. Those who design it never consider the direct self-consumption usage, the SOLE sound renewable usage. And that's "designed for renewables".
Now the best: from the lowest segment appliances featuring cloud-tied crapplications, with useless features but NOTHING usable locally, not even dry contacts to being controlled by a homeserver to the highest segment like smart wall box for EV recharge where only VERY few offer basic logic like:
- charge ONLY from renewables
- charge from renewables but watch the clock, ensure this minimum SOC for $this_time seeing actual renewable power and local grid maximum power
- charge as fast as possible
- slow charge targeting $SOC for $this_time
ONLY few months ago a new CCS standard appear dealing with bi-directional usage to enable V2H applications, of course NO ONE have implemented it so far even if EVs are there since decades, albeit marginal. Most EVs use 400V DC batteries, most solar inverters support domestic high voltage batteries who happen to be equally 400V DC, with the very same BMS and concept than cars batteries but no, you can't just plug the battery-on-wheel like the stationary one even if they are the same, nobody though at that so far apparently.
At automation level? NEARLY ALL "smart" stuff are unreliable wireless devices with various radio tech/protocols only VERY FEW are wired even if from simple ModBUS to powerline and equally complex TCP/IP stack with classic ethernet cost the very same and happen to be far more...
Seems like a no-brainer once you think about it ... in the worst case of a flow heater you bring up the water to temperature, let it flow over your body and dump it with most of the heat you put into it.
Systems like the one liked above improve on that by recovering some of the energy. I don't know what the "official" way of installing this system is, but I would just put it in the cold water path and have a thermostat controlled faucet to "switch" to the now-warmer-water gradually.
But I think instead often the heat recovery is installed somewhere in-line after the boiler, to make piping easier, but it makes heat management obviously more complicated.
Tapping the waste water as heat source for a heat pump seems like a better idea.
Better to just have a filter on the drain similar to a dishwasher.
Or am I missing something?
For simplicity, if your hot water system was already a heat pump, you could run it past/into the cold side. No real efficiency gain vs exchanging it with the cold water (actually a loss in theory) but might be cheaper.
I was thinking a cop of 4 would be able to extract 4 units of energy to the heat exchangers 1. But there's only 1 unit of energy in it to extract, which the heat exchanger is already extracting basically for free.
But it should be more efficient to run a heat pump against the heat exchanger's inefficiency/delta then to let it happen and compensate with an ohmic heater.
Yes, the wastewater discharge with a 100% efficient heat pump might actually leave colder than the fresh water comes, due to heat loss to the room exceeding the work required to pump the heat against the exchanger's losses.
The replacement for the lost heat would happen to the equilibriated water and could happen with a heat pump. In principle (if your heat pump and exchanger is perfect) this generates no entropy so is more efficient than putting things with finite temperature delta in contact. In practise it's probably just simpler and requires a smaller heat pump.
Whether you use the waste water (which will still be a degree or two above as exchangers aren't perfect) or whatever your normal source is (ground source may be warmer) would be about cost and making the heat pump work for not-the-shower too.
http://www.heatsnagger.com/product/hxdrain-dwhr-for-shower/
In massive American homes the water heater could be hundreds of feet away from the shower.
Where I'm from, we take Navy showers[1], where you only use water to rinse things off. Basically:
1. Run water on you so you get wet everywhere, turn the faucet off.
2. Apply body wash and shampoo.
3. Turn the faucet on and rinse everything.
4. Done.
The actual water-using portion of this is less than a minute.
[1] https://en.wikipedia.org/wiki/Navy_shower
Gas boilers with long pipes means you need to wait for the hot water to come through, and if you stop it again you then have a load of cold water just waiting to take you by surprise.
Cutlery too. The United States doesn't have kitchen knives, we have to tear meat and bread with our hands, it's terrible.
Even a minute of initial water flow should generate enough heat in the enclosed area for the minute or three you need to comfortably apply whatever gels, soaps and shampoos you need. If that's not the case, then either you're in a place with harsh winters and it's the coldest week of the year, or your bathroom / building needs serious insulation rework. In that last case, I guess the water waste is a non-issue compared to overall heat waste due to poor insulation.
Also note that none of that precludes you taking your sweet time in hot water if you need it for e.g. relaxation reasons. It just doesn't make sense to keep it running for the part when you apply the cleaning agents.
I get the efficiency of Navy Showers, but water is cheap where I'm at. Would be a lot of extra effort and discomfort for negligible savings. Maybe it makes sense if you live in a desert or, as the name implies, you're on a ship
No, we just don't like wasting water/heating. I don't know how much extra effort it is to turn the tap off when you're done with it. It definitely doesn't feel like effort to me, and having the water run while I'm trying to avoid it so I can soap myself up is very annoying.
> water is cheap where I'm at.
You are in a thread where people are installing heat pumps to reclaim the wasted heat. Is saying "how about you don't waste the heat in the first place" really that crazy?
You can also compress/save used aluminum cans and periodically sell them to a scrap metal dealership for money. Quick check shows scrap aluminum cans are selling for a national average of $0.45/lb, and it takes about 32-35 12 oz cans to accrue 1 lb of aluminum cans. Assuming you go through a 24 pack of cans per week, enjoy your ~$1.30/month savings for hours of effort!
At least food is cheap, I guess!
How cheap is water in your place you'd consider this a micro-optimization? In my country, unless you're tech-salary-equivalent-or-above, not doing it - and doubling or tripling your hot water (or water + gas) bill - would noticeably cut into whatever discretionary spending money you have.
Micro-optimization would be "grey water reclamation" with a bucket placed in a sink, to reuse hand-washing water for flushing the toilet. Which is something my wife and I started to do a while ago, and while we don't need to do it, the drop in utility bills for near-zero effort is impressive enough that we continue anyway.
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[0] - Or should I say "Standard Showers", as I literally can't think of anyone who doesn't turn off the water for soaping after being made aware that water and heating both cost money.
So it's not a negligible amount of money, but it costs less than my combined streaming services. Cutting it by 20% would allow me to afford... another streaming service? A couple of days' groceries?
I'm also not sure what kind of showers you're taking, but I know from experience being forced to shower with a mostly-clogged drain for a couple of days there's no way my shower head is filling the tub even over my ankles before the shower is done (5-10 minutes). So "several bath tubs" is an exaggeration unless you're taking extremely long showers or your showerhead has the efficiency of a fire hydrant.
And I guess we're just blessed with plentiful water on the US East Coast, because I've lived in several states on this coast for my entire life and I'd never even heard of "Navy Shower" until college, and only then as a reference to... the Navy! Or sometimes we hear about Californians being asked to do so when a drought hits.
But whatever, you do you! If it actually does make a difference for you than go for it!
Your math comes out similar to what I remember from the utility bill (which I currently don't have handy, so I won't provide exact calculation). It's not life-changing, but it's not nothing. A couple days of groceries worth of money we could use for arbitrary discretionary spending, at a cost of... pretty much nothing, I don't consider this habit to take noticeable effort over keeping the shower running. And with several more such "little to no effort saves you a Netflix subscription" habits, this adds up. You can probably ignore $100-$150 / month saved off utility bills and incidental costs when on a tech-equivalent salary, but many people wouldn't.
(And yes, we mind the opportunity costs too.)
> I know from experience being forced to shower with a mostly-clogged drain for a couple of days there's no way my shower head is filling the tub even over my ankles before the shower is done (5-10 minutes).
That's an interesting data point. I may have exaggerated with "several tubs", though my actual shower, left on for the entire duration and with drain plugged, would fill a tub[0] to the level where, were I to lie down, the water would spill out[1]. We may have different sizes of the tub/showering compartments, and possibly different pressure levels and flow rates. Eyeballing it now, the bathroom faucet gives some 10-12 liters per minute, maybe a bit more; this is cut down to some 8 liters per minute when going through the shower head in default setting.
> And I guess we're just blessed with plentiful water on the US East Coast, because I've lived in several states on this coast for my entire life and I'd never even heard of "Navy Shower" until college, and only then as a reference to... the Navy! Or sometimes we hear about Californians being asked to do so when a drought hits.
I never heard it called this way until 'stavros mentioned it today! For me, it was always known as the "mom asking 'why are you wasting water in the shower?' shower" :). We don't need to do it, it just feels unnecessarily wasteful if we don't (and it makes noticeable difference in the bills for households on median salary or below).
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[0] - The 32' x 60' like here: https://www.thespruce.com/bathtub-sizes-reference-guide-1821..., which is similar to "standard bathtub" of 70x170cm where I live.
[1] - I admit I got confused by my intuition. A "standard bathtub" similar to [0] will hold over 200 liters of water, which is of course way more than the shower head would provide over the duration of my shower. When I wrote about filling bath tubs, I thought intuitively about the volume past which you can't lie down without it spilling out.
So over the course of a 10 minute shower that's 25 gallons, * 0.0065/gallon = ~0.16/shower. Sometimes if I'm working from home and not exerting myself physically I won't shower (dry skin so I don't stink after just one day), so say an average 6 showers a week = ~24 showers a month = 3.84, and times 1.5 for the sewer cost (roughly) = $5.76 total / month from the water/sewer usage. Harder to calculate how much water heating costs since the same hot water source goes to all the fixtures/dishwasher/washing machine, and it needs to maintain temperature. But let's be generous and say 20% of the non-winter gas bill is strictly due to heating water for showers. So roughly $14. That's a total of $19.76. Let's say by doing, call them maximum-efficiency showers that take only 1.5 minutes of running water instead of 10. So an 85% reduction in costs would be $16.796 / month in savings. Again not nothing, but I'm not sure it's worth the discomfort either. Plus the steam helps with my shave a couple of days a week. I could also get most of the way there just by taking quicker showers, and honestly I'd rather do that. If I'm going to be uncomfortable, I'd rather have time discomfort than temperature discomfort :)
But yeah I guess it's also a cultural thing. And I'm sure there are some families over here that shower that way, I've just never encountered one in conversation/life. You certainly don't see it in gym/school locker room/dorm/pool showers, and in media, as you pointed out, people have the water running constantly.
I used to have a shower that didn't have a thermostat so it was fiddly to get the temperature right. That one I'd lean in and out, sure.
Municipal sewage is one of the main things we need to focus on atm. We essentially mix black water with grey water, turning the whole concoction into black water that needs to go through sewage treatment. Woohoo, government screwed us over yet again.
Instead, we should re-use grey water in the garden or at least have a separate municipal dump for grey water.
That's highly dependent on location and time. And even if it's renewable, it isn't necessarily cheap, and the people in this article are mostly motivated by high energy prices, not renewability.
My total yearly spend on showers is about $100 a year, and there's lot of things I'd give up before that to save $100, in dollar or energy use terms.
https://www.omnicalculator.com/everyday-life/shower-cost
Eventually I'll get a new valve, but right now changing the water flow also changes the temperature.
Wouldn't that money return more via a solar system, or better insulation?
There does seem to be a copy of the 2.2 version (latest is 3.0) floating around so nothing stops you using that - as someone has done: http://ihormelnyk.com/Content/Pages/opentherm_library/
I couldn't find version 3.0 though.
Edit Although to be fair it's way more open than something like EMS, which is what my Worcester Bosch uses. There's some info on that from reverse engineering efforts but that's it.
If I was buying a new boiler I'd try and get one with Opentherm support for future proofing. Surely more controllers will come out. Isn't much at the moment AFAIK.
Looks like the "Control setpoint" is the relevant command for flow temperature.
Usually the boilers are also oversized for houses here. The temperature differential is not big enough and you waste quite a lot of energy through steam.
Finally, the system boilers are also the most common (as opposed to combi-boilers) and for that reason you are not supposed set them below 60 degrees.
Building insulation for one was a shocking factor. It's 2022 and stuff that was considered "normal" in Europe 10 years ago is still a problem in a lot of UK buildings. Worse, it doesn't even require rebuilding - you can improve the situation incrementally, so it should be a no-brainer for a government to subsidize, yet they aren't doing so.
I've lived in social housing in France that was much better insulated (it would be considered "good" even by today's standards) than places here that rent privately for 2k+/month.
Is it for heat pumps that work slower? It still implies to me that insulation is lacking.
I'm still somewhat dubious of 'better' thermostats though. I just turn it on when I feel cold. I don't see how a thermostat could improve on: 'The heat only goes on when it's cold enough for me to turn it on'.
I've got cavity wall insulation, 30cm of insulation in the loft and recentish double glazed windows and the bedrooms stay warm enough at night with just body heat and residual heat. The heating on goes on in the evenings (still hasn't gone on yet) unless it's really cold. I don't think any of those are particularly onorous jobs to undertake.
My house has something called ETICS* (basically a thick outer layer of polystyrene with a weather resistant paint. Ugly stuff, but it works wonders!), mineral wool insulation in the attic (which I'm supplementing just in case), underfloor insulation with extruded polystyrene and of course double glazed windows. We don't turn on the heat until it's 3 degrees or less outside. Thermostats and stuff like in the article bring too small benefits to really consider.
*) https://www.ea-etics.com/etics/about-etics/
Ultimately my direct debit for gas electricity is only £10pm at the mo after the govt bung so my house is about as good as I'm going to get it anyway.
For those of us with solid walls it's expensive and very disruptive to install internal/external wall cladding. I happen to live in an area where I'm not even allowed to install external cladding.
Theoretically it could use feedback from all the thermostat valves (and adjust the burner to keep the most-open valve near (but not at) 100% flow), but that requires feedback from all valves rather than just an outdoor temperature probe and a parametric mapping curve that depends on radiator style, desired indoor temperature, and building insulation.
The lower the level the more efficient it is. It's better to run the boiler on low for 3 hours, vs high for 1 hours.
How do you know if to run the boiler on low or high? You check the outdoor temperature. You also do a backup: If the boiler has been running for more than an hour, increase the temperature slightly every 15 minutes. Once it goes off, reset the temperature to the one determined by outdoor temperature.
Short of getting a newer heat pump, nothing I do will impact my bill in any significant way. I already do most of the smaller stuff.
I’m using a metal wafer pool heat exchange and a boost pump for pressure on the outgoing side.
I have to admit I haven’t thought out whether this will galvanically disappear the copper.
I’ve also thought out putting a 50’ spool of pex inline, but unsure of pressure loss issues. Or maybe that would be good for the house pipes…
These types of articles are for the general population which may not realise things about insulation. Or energy, or phase changes etc. And generally sent interested in how things work, or efficiency, except to the extent it costs them money.
What would help is higher regulatory energy standards and better enforcement. I’d settle for making sure builders actually use insulation and don’t leave obvious thermal bypass/bridging across it.
My 20 year old new build property leaks heat due to it being a “plasterboard tent” (thermal bypass due to missing sealing around dot-and-dab drywall). If a building inspector had actually checked this before signing it off, it’d have been rejected.
Yes regulation and other stuff is sorely needed. But in the context of what an individual can do 10%-20% is nothing to be sniffed at. And I suspect that severely underestimates the savings compared to the average person, let alone the worst offenders.
If collectively it means 0.00000001% change I don't find it provides much "I did a good thing" value and the time would have been better spent fundraising, petitioning politicians, or maybe even just raising awareness towards say... improving a law that makes a collective 1% difference.
The best time to plant an apple tree was 20 years ago. But if you didn't do that, the best time is now.
However, the hardest thing to do when figuring out what uses / wastes electricity in your home is establishing a baseline with the most appliances / systems turned off as possible.
My apt is well insulated, but for me it's still crazy (even packing the fridge with as much thermal mass as possible), and furnace / AC turned off at the breaker my apt still uses around 8KWH per day. Water heaters and refrigerators have a long way to go! Curiously, leaving my AC / furnace completely off or on at about 80% cooling a 20F delta uses very little power, exciting how efficient modern climate control is :).
The water heater is the real power suck for me. Here's a couple typical days: https://i.imgur.com/Hx8Zgk4.png
so far i haven't noticed any difference, but i think that's the point.
The ability to do this kind of thing has been around a long time.
I’ve had to fool the ecobee into thinking I have a heat pump (I guess I do technically) just to avoid it turning on the aircon when it’s below 18.6C outside.
I think it’s called the heat pump lockout setting or something.
But I can’t set the threshold higher than that, so I still end up in situations where it’s 20C outside and the AC is on to get it under 23C when really I should get the cue to open windows.
Simply put I've set it up that during electricity peak times the boiler doesn't try to heat water to save on electricity costs. Heating water is all done in the off peak hours with some easy calculations. Also I tend to set my boiler to a lower temperature (ie. 58 degrees) during weekdays and higher (60+) during weekends or holidays. That way I always have hot water and get rid of legionella growth.
What I can see I'm using about 1.5 - 2kWh a day for keep 100 liters of water at at least 55 degrees. While the manufacturer of the water heater says the device should use between 7 and 9kWh a day. I really would like to optimize it any further, but it seems that I've hit a wall.
I've also looked at instantaneous water heaters, which could be even more efficient. But those with enough capacity need 400V, which I don't have in my apartment. Also I would probably have legionella growth in my regular water heater if I want to save even more electricity. Which would be a health issue.
In my case, I was able to get rid of my dehumidifier in the basement and the window unit in the summer. Paid for itself in ~6 months.
I find that in cold rooms, my fingers slow down even if I'm warmly dressed.
typing with cold fingers might be a recipe for arthritis.
Bathrooms and kitchens are a special case, which can be addressed with ventilation. One of the upsides of keeping your home cool in the winter is it's much cheaper to circulate in new air from outside. You get to have fresh air all winter without paying to heat all that air up. I believe fresh air throughout the year has many health benefits.
It might be like you said only if you don't use that room, or you have a big house so maybe you don't use most rooms and then you don't fill them with humidity from your own breath. Walls are cold but also dry.
Opening the windows in the winter is how you let all that humidity out.
Absolutely, being able to open your windows is a big advantage of keeping your thermostat low.
Going back and forth over winter break I definitely noticed a productivity shift being some place I was warm and comfortable.
Perhaps there are less noticeable psychology benefits for it being cold but I do not think being uncomfortable and dealing with it is a long term strategy for success. And probably completely impractical if you live with other people in the same house.
If that isn't sufficient, there are still cheaper ways to deal with it than adjusting the furnace. A low power radiative space heater (the sort with a reflective dish) can be very efficient at heating up the person it's pointed at without heating up the whole room. Having a warm drink to pick up and sip on also helps; it'll warm your fingers directly and also give your core a little boost of heat. Heated electric blankets are also extremely effective.
Also, they either a) don't own a piano, or b) don't care about taking care of the piano they own.
Parents in nordic countries leave their babies outside bundled up in strollers in the winter to nap.
The key point here with this napping thing that did the rounds is that this is just for short naps. People in Norway/Finland do not leave their babies in a cold environment for long periods of time. Presumably the main reason they do this cold outside nap is that it's easier to get a baby to fall asleep in a pram (safely wrapped up) but very disruptive to then bring it inside, where it will be warm, have to undress it and then inevitably wake it. But I don't know, there are probably also other reasons. But parents in nordic countries are the same as everyone else when it comes to heating their homes appropriately, especially for night time sleeping.
Personally I would imagine even things like eating would be harder if the room is too cold and the infant must always be maximally layered up. It doesn't need to be any harder.
As for guests, you can turn up the heat when guests come to stay and still see dramatic energy savings, vs running the heat full blast the whole winter.
Anyway, enjoy your... [checks thread]... bathtub waste water heat reclaimer. I'm sure that will make a big difference to your energy bill when your thermostat is turned up to 30C in January.
alternatively
> freeze your nuts off for the environment!
Which lie do you do want to believe for making your poorer?
- have one fewer child (60 tons of carbon dioxide equivalents)
- live car free (2.5 tons)
- avoid one round-trip trans-Atlantic flight (1.5 tons)
- Buy green energy (1.3 tons)
- Buy a more efficient car (1.2 tons)
The source lists a chart with more actions:
https://www.science.org/content/article/best-way-reduce-your...
But instead people focus on recycling and replacing lightbulbs while paying no attention to the 20 flights they took last year.
Perhaps even making inaccurate value judgements on those that didn't recycle that year but also took 0 flights.
Most heating systems where I am have one...
One big advantage over a on/off thermostat is that it the room temperature doesn’t fluctuate as much.
These "tips" are good, but target the wrong market. Those who have the resources and/or knowledge to implement them are either already doing it, live in a well-insulated property, or make enough to not care about the bill in practice. Those who are actually affected badly by the recent energy crisis have neither the resources to implement these, nor will it make enough of a difference to their situation anyway.
The main problem here is that the government has completely failed its citizens by letting the situation get to a state where a significant proportion of the population is considered to be in "fuel poverty".
Blaming the Russia/Ukraine war is a convenient scapegoat but isn't the answer either. Being forever dependent on foreign energy is a major failure for the government, and even now, I'm not seeing anything being done about it. Most short-term energy subsidies won't address the problem (they may solve this problem, but won't prepare us for the next crisis - not to mention that personal energy subsidies do little when you still have to pay businesses' energy prices in the form of increased costs of goods).
There solutions IMO would be:
* massive subsidies on insulation. UK building standards are shocking by European standards, but the good thing about it is that incremental improvements are both possible (no need to demolish the building) and don't require scarce materials so no supply chain concerns there, merely money concerns the government can subsidize
* solar subsidies, and actually making feed-in tariffs competitive to encourage people to invest in it. This would reduce our energy dependency during the day (which conveniently is when the demand is the highest).
Government borrowing for the above points makes sense because it can and will be paid back down the line (solar lasts 10+ years and efficiency decreases gradually, so you'll get something out of it even 30 years later), unlike stupidly subsidizing people's energy bills without addressing the root cause which will be a one-off expense with no expected return.
1) giving them the benefit of the doubt, there might be rational reasons for it that I’m not aware of - unlikely but possible
2) a politician’s primary objective is to get re-elected and accepted/appreciated by their peers. They are usually rich enough to withstand whatever crisis is plaguing their country anyway, so they aren’t afraid of the consequences of their actions. Therefore, politicians probably benefit from what they do now more so that what they’d get if they actually enacted policies that benefit the common man at the expense of large companies and/or lobbyists.