All the quotes I got were for a day of install. I assume it'd be one tech, but let's be generous... 2 techs x 8 hours x $150/hour = $2400 for labour. So that means either the pump itself costs $15k, or somethings wrong in this market.
Or my alternate hot-take (or cold-take?): Great, now if someone can crack the engineering challenge of an air-to-water heat pump water heater that doesn't turn your basement into a walk-in refrigerator, that'd be great.
Depending on your market, Sanden and Mitsubishi make air-source DHW heat pumps where the evaporator/heat source source is remote (i.e., outdoor) rather than integrated with the tank. I can't speak to Mitsubishi's line but IIRC Sanden has the DHW go straight to the outdoor unit, but then you may need freeze protection, which I think Sanden provides via heat trace. When my current water heater bites the dust, I plan on getting a Sanden, and looking in to the feasibility of making a glycol loop between the outdoor unit and an indoor "indirect" tank to eliminate the need for freeze protection.
Thanks for the tip! Where I am Mitsubishis seem to only be available through big-name installers, and the only thing they offered me when I talked to them was the all-in-one style that cools your basement. Living in an old house with not great insulation between floors, that was a hard no-go. I'm now googling the Sanden ones and getting some promising results I hadn't seen before.
What you want is an "Ecocute". It is a air source heatoump supercritical co2 tanked hot water system. Designed for the Japanese market. Without install a 500l tank version costs about 1.5k usd in Japan. So you should be able to get one installed for about 20k usd in the US. If you beg the HVAC guy of course.
The all-in-one heat pump hot water heater pulls in warm air from its surroundings, pulls the heat out of it and puts that into its water. Then it lets out its "exhaust" colder air. Ducting to outdoors improves things, because it doesn't put that cold air back into your basement / utility closet, but you're still pulling heat out of the air - which your house heater now has to put back into the air - and unless your space is perfectly airtight, that's probably just going to be sucked in via the nearest air gap to outside.
It's a bad system. Split systems make sense, and I know they exist, but they seem weirdly rare.
The ducting brings the temperature drop to an almost unnoticeable delta. If you are worried, just install it near your furnace. It’ll eat radiant heat from that corner that would otherwise go into the walls, egress windows etc. Every other part of the year, you either don’t mind or benefit from the cooling.
I have the stats from my own Rheem to know I’m coming out ahead financially during winter and also haven’t seen a meaningful swing in the basement climate.
I’m a regular participant in that linked blog, too. :)
I recently installed a (quite large) heat pump for less than that, though it came close. A lot of the cost came from a few things:
- the Canada premium: these sorts of things are just more expensive here. The base price was just higher than I could find in the US, but obviously importing is too expensive. I think the reason for this is there's almost no stock.
- adapting my house: the house I live in was built to have central air added to it, but even so the pipes going from the furnace room to the outside had to be insulated both directions instead of only one for an AC. Ripping up our basement ceiling to do this added a lot to the cost. An unfinished basement would help a lot here.
- HVAC company confusion: I had to go through like five HVAC companies before I found one that would believe me that I really wanted it. The one I got is a commercial outfit, so their prices were just higher. Even they were skeptical but they were willing to work with us, and by the end they talked about doing more installs so that was nice.
I think the cost for the install and unit itself was $12k for a top of line carrier unit capable of working down to pretty low temperatures. But we already had a compatible carrier furnace and exchanger. Was another couple thousand for ripping up the basement, which we had other contractors do.
This was also literally during the heat dome last year. They had to ship the unit across the country.
You can definitely do it for cheaper. There are $1000-$3000 single-head units available online for self-install, and you could hire an HVAC person to come out and do the high pressure line part of it (or all of it) for a similar range. It just gets expensive with the name-brand ones. For some reason that $2k-6k turns into 10k-20k when you switch to a name brand (e.g. mitsubishi). They're only available through specific installers, and using a non-authorized installer means your warranty is void.
FTA, they already measured it and will deploy in 2024:
> The prototype delivers 100% heating at 5°F at double the efficiency, and 70% to 80% heating at -5°F and -10°F. DOE’s Oak Ridge National Laboratory validated the performance and efficiency of Lennox’s prototype.
> Lennox is one of nine manufacturers competing in the CCHP Technology Challenge. Its product and others that meet the CCHP Technology Challenge will undergo trials in cold climate regions over the next two years to demonstrate performance, efficiency, and comfort when applied in the field throughout a winter. Deployment and commercialization are planned for 2024.
I just bought a Mitsubishi mini split system to replace our oil furnace and bring A/C to our house here in New Jersey for the first time. Their high end outdoor units heat down to -13 F, which is colder than I've ever seen here. It arrives in august.
Gree has a system that claims to have full heat down to -31, so I'd say just keep researching and you'll probably be fine.
What is the plan for when it gets colder than -13? Do you do a hybrid with your furnace? Some other solution? Thinking of getting some heat pumps myself.
In nearby Philadelphia, it rarely gets that cold, and not for extended periods of time, but when it does, we bust out blankets and space heaters to make up the difference.
I’ve looked into heat pumps pretty extensively for my upcoming boiler replacement (looking at an air-to-water in my case, but very similar principles apply).
In my case, the 99% design temperature is high single digits Fahrenheit. For the 3.5 days/year colder than that, the plan is to have the house “coast” on thermal mass.
That’s for cases where the ambient temp is below design (where the heater can make heat but just no longer enough to keep up with the building heat loss), not for when it’s below a cutoff (where the heater shuts off entirely). In my case, that’s so far below design temp that I’d expect to never see it. (We hit -9°F in 2016 and would have to go all the way back to 1943 to find a low of -14°F.) If it happened, thermal mass would start to carry us with electric space heating keeping the house from totally freezing.
I might invest in some backup propane heaters as well (a buddy heater at Walmart is pretty affordable and is safe for indoor use). I feel like in blizzard-like conditions having electricity be your backup plan might not be too wise.
We usually switch to the wood stoves once winter sets in. Our forced air furnace is incapable of making the house warm and cozy because duct reasons that I can't really fix.
I'm planning on getting rid of it altogether and doing the heat pump(s) most of the year, the wood stoves in winter and reclaiming a lot of headroom in the basement and an entire utility room that the furnace currently takes up.
They way it works in practice is that the air handler that comes with the heat pump will contain a backup emergency heat element in case it gets too cold or there is a problem with the heat pump. The cost to run it is much higher, but it should only run in the most extreme cold temperatures.
You probably should not wait: it will be 2 years of testing according to the announcement, and if you’re doing a retrofit most the cost of installation will be installing the transfer lines inside, mounting the unit, etc (opening walls and closing them back up). Transferring from an old outdoor unit to a new one should be a fraction of the original install cost (basically just the new unit cost plus the cost of hooking it up).
But, if you’re willing to wait or pay extra for the efficiency gains, you might be even better off getting set up with a ground source heat pump now. The install cost is more up front, but because ground temperature is higher than air temperature in winter and lower than air temperature in summer, the differential you need to pump in or out is a lot less, and therefore much more efficient. I don’t think any air to air heat pump in the next 20 years will be as efficient as a ground to air system you could install now. The air to air systems just have lower up front install costs.
In the US, there is still a 30% federal tax credit for ground source heat pumps as well. Many of the other energy credits have sunset (such as solar, I think)
One tip from my install, is to go with single zone units. I did a multi-zone and the way the control system works is kind of weird. They also don't have as good of a turndown ratio[0] as smaller/single zone systems, making it less efficient.
That's great news. I have a heat pump in my house, but still need to use the gas furnace when the temp drops below 40 degrees Fahrenheit.
A repair person goofed the settings last January, and I didn't notice the furnace wasn't kicking in until the end of February. My electric bill went from $150-ish for Feb 2021 to $450-ish for Feb 2022.
It’s not about ‘working’, it’s about the cost of electricity when it gets colder and the efficiency drops. Gas is pretty cheap for heating in most of the US…
“Lennox International… developed the first prototype that achieved the Technology Challenge’s standards about a year ahead of schedule. The prototype delivers 100% heating at 5°F at double the efficiency, and 70% to 80% heating at -5°F and -10°F.”
The release goes on to say they expect commercialization and deployment in 2024.
Perhaps I missed it skimming the article, but my question is, double the efficiency compared to what? To the current state of the art cold climate hear pump? Or to a resistive heater?
Efficiency is a misleading word for heating, because the units don't match; they are both energy, but different "type".
The denominator is fuel energy lost, but the numerator is thermal energy change within an area of interest.
A heat pump moves thermal energy from outside, changing unimportant thermal energy into good thermal energy.
Yeah take the energy you pump from Reservoir A to Reservoir B divided by the energy requires to do that and that's COP. Which you can think of as an efficiency.
Slightly more precisely: you're using less energy (in the form of electricity used to run the heat pump) than you are moving into/out of the heated/cooled space.
No OP but yeah heat pumps are very efficient some >300% efficient since you're just "pumping heat" from one place to another not generating it.
Even electric heat alone is 100% efficient no incomplete combustion or degradation over time. Efficient bu much more expensive than just moving heat already in the air.
Ground-source are better for now since they are moving heat from a relatively consistent source the Earth. It's about 15C to 25C one meter down where the ground-source heat pump lines are run.
Generating vs moving heat I think is misunderstood by people or really more likely they just don't care. As long as the bill is low!
If you could really move heat 300% more efficiently than using a resistive heater to generate heat, couldn’t you just move a bunch of heat to power a steam turbine and get a perpetual motion machine?
It's not entirely clear what you mean. But, you say "if you could really ..." as if ground-source/air-source heat pumps don't do this exact thing; do you think they don't work?
Running a steam turbine by pushing water down a borehole to come into contact with a high-temp (>100°C) source has been done; it's not perpetual motion. Energy pumping the water is << energy output from the steam produced. It's solar energy that's being used, ultimately.
No, first of all perpetual motion machines don't exist, will never exist.
The 300% efficiency means if you had 1 Watt you could use it to power a fan and coolant lines to move heat. Or use 1 Watt to generate heat and then once made to move that heat.
The moving of heat already existing in the air (or in the ground) is more efficient than generating the heat and then moving it.
This just seems like unnecessary hair splitting to me. Obviously the efficiency of something is subject to the important inputs and outputs involved.
If someone asks: "how efficient is this heat pump at heating my house?" And you start digressing about how that's the wrong question to ask you'll be giving them an impression opposite reality, which is for most people: it will use less electric energy than heat energy it puts into your house, almost all the time.
There are theoretical upper bounds on the COP though. As heat pumps get better, it may some day make sense to say things like "this heat pump is 95% efficient, so there is no point in replacing it".
COP of 2 at 5F is good. But... Mitsubishi has one that is 3.13 at 5F and LG has one at 2.65 at 5F, so this isn't really the breakthrough that the press release claims, the breakthrough is that a US company is doing it.
What they probably meant is that at 5°F the pump can supply 100% of the heat required to keep a house (of certain size) warm, with no other form of heating required. At -5 and -10, it can still extract enough heat from the outside to supply 70-80% of what's needed but you will need other means of heating such as resistive electric radiators to complement the heat pump.
Surely not engineering way of thinking but that's a common heat pump metric for ordinary people.
Ah, I see. I figured they'd keep the input energy constant because otherwise you're not saying much at all (you could figure that the efficiency plummets and you'd be better off with a space heater).
It's possible. Also possible it's barely outperforming the space heater at the lower temperature and input power has increased. They've not told us enough.
The energy input goes down because it physically can't run a differential high enough to get full heating output.
They could choose the lowest temperature, find it's power input, then fix it at that amount. But at low temperatures the concern is usually less "efficiency" and more "am I going to freeze to death", because in most of the cold areas temperatures aren't usually that cold for that long (though in others it definitely is, and if you're running at 1.6 COP for a significant amount of time, you're better off with more insulation than a heat pump).
It says "double" the efficiency, so I assume they mean 2x the COP of the previous model at 5F, and 1.7-1.8x the old COP at -5 and -10F.
A COP of 2 @ 5F isn't a "breakthrough" vs. the first commercially available model I could find numbers for, and a COP of 1.5 at -10F seems implausible:
It doesn't really compare since ground-source/geothermal systems are designed to work with a smaller temperature difference (since the earth stays about 50F most of the year a few feet down).
Business wise, if this really works at 2COP at 5F, this might take over most of the market served by ground source heat pumps though.
Does anyone know why there has never been any breakthroughs in air conditioning for 50 years? Windows air conditioners have been incredibly heavy, loud, expensive, and resource-intensive for so long. Even a small room needs one that is back-breaking to install. And pretty much everyone in the world (except those with central air) needs a couple of air conditioners now.
Sure the "efficiency" is improving but it's mainly tricks for turning it on/off at better times. I know there are some U-shaped ones now, but it's just a slightly different styling.
Edit: two commenters pointed out examples of air conditioners which are 77 lbs and 56 lbs. As a comparison, the OSHA recommended lifting weight is 50 lbs. I would love to see someone apply Apple's obsession with thinner, lighter, "revolutionary new design" to ACs.
Idk this "toshiba" AC has a built in heat pump and operates at super quiet levels.
Would I call it a "breakthrough", likely not. But it is a meaningful improvement over an AC released decades ago.
Check out the inverter type ones such as this one [1] It isn't light but it is quiet and adjusts the amount of power it uses depending on cooling needs much better than a typical window unit making it more efficient.
The Midea U window AC units are a really good product. I am easily cooling a roughy 1,200 square feet space with only one of the 12k BTU units and a few ceiling fans, and it typically gets into the 90’s F here in the summer with significant humidity.
No affiliation to Midea just a satisfied customer.
I agree. The U shape is a gimmick, but a good one. It helps it be quieter inside, but even outside they are quite quiet. I have whole house AC, but I like the windows open, I like being hot. Just not when I’m sleeping. Basically only downside is a truly terrible app that is the only way to access just a few features.
Terrible doesn't begin to describe that app. Honestly what does the turbo button in the app even do?
I have one in a room on the far end of the house that the main AC can't reach, it helps reduce power usage since I can keep the rest of the house warmer.
AFAIK the physics of heat pumps is considered to have been fully figured out for ages and all that's left is the engineering. Maybe it wasn't considered a "sexy" enough topic to nerd out over and hyper-optimize?
Edit: it might also be an issue of diminishing returns of better efficiency compared to how difficult it is to produce and maintain a better unit. Thermodynamics can be a pain like that.
We got a U-shaped one for a big open attic space and I'm a fan of it. It cost more and was a little bit more drama to install (came with a big support bracket thing), but it's very effective and quiet. We meant it as a stepping stone to eventually putting a mini-split setup on that side of the house, but it might end up just being the long-term solution.
EDIT: Oh lol, the unit we got was actually one of those Midea ones linked in a sibling comment.
As I mentioned elsewhere: https://news.ycombinator.com/item?id=31791936
there is a company that claims to use thermoacoustics for general heat-pump duty. I believe they are targeting European style hydronic heating. Aiming to be efficient whilst still producing the 80c water that many older hydronic systems here in Europe still require.
Interestingly, they aren't that loud because any sound lost is energy lost, so they try very hard to 'keep it quiet'.
Mini splits are widely used and have become dramatically more economical and popular over the last decade or so. They are much quieter and more efficient than window units.
Some areas (cough nyc cough) may need some regulatory breakthroughs but the technology is there.
Talk about moving the goalposts. You asked, people answered. The revolution is that you can now buy an 8000 BTU unit that weighs little, costs almost nothing, and can be installed anywhere in a few minutes.
Thermodynamics are harsh mistress... Add that to limitations on what can be used as refrigerants. The reality that these systems need to operate with rather long duty cycles for decade+ at minimum. And the reality is that there isn't much magic in how they operate. Compression and expansion of gas.
Computers are actually a very special case. They don't really do any physical work in sense other stuff does, thus miniaturization gives lot of gains there. I have long said that small drones are answer to flying cars. We have them and they are small, but lifting people is hard work.
"Lisa, in this house we obey the laws of thermodynamics!"
It's physics and thermodynamics. It's basically the same as with any heat engine, internal combustion engines included.
There is a certain maximum theoretical efficiency that is not 100%. When we build real machines (not theoretical ones) there are real world losses like heat loss, fluid flow friction, moving part friction, electrical inefficiencies, etc. Those real world losses van be gradually worked on over time, improved incrementally to yield small gains in efficiency. But never large ones, and never more than the theoretical max efficiency, which is not 100%.
It's like hybrid cars (not plug in hybrids, but just gas powered hybrids), they've doubled or trippled the mileage compared to a comparable regular car, but they will always need gas, they will never be 100% efficient.
Same with this. There will always be some fundamental electrical losses in the copper in the motor, air gap losses in the motor, friction in the bearings and fluid, heat losses to the environment, etc. It's the cost of doing the work. There is no free lunch, so we can only incrementally improve the little losses over time.
My understanding is that heat pumps can be over 100% efficient because they're actually moving heat from A to B where one side is the outside environment. It doesn't violate thermodynamics if you view the Earth as a closed system. The heat pump itself is not a closed system.
That means you need somewhere to move the heat to, and the thermoynamics of heat capacity are not forgiving if you are trying to make something lightweight. You need atoms and lots of entropic states to store heat :)
Thanks for highlighting this because it's a common misconception.
"The coefficient of performance or COP (sometimes CP or CoP) of a heat pump, refrigerator or air conditioning system is a ratio of useful heating or cooling provided to work (energy) required.[1][2] Higher COPs equate to higher efficiency, lower energy (power) consumption and thus lower operating costs. The COP usually exceeds 1, especially in heat pumps, because, instead of just converting work to heat (which, if 100% efficient, would be a COP of 1), it pumps additional heat from a heat source to where the heat is required. Most air conditioners have a COP of 2.3 to 3.5. Less work is required to move heat than for conversion into heat, and because of this, heat pumps, air conditioners and refrigeration systems can have a coefficient of performance greater than one. However, this does not mean that they are more than 100% efficient, in other words, no heat engine can have a thermal efficiency of 100% or greater. For complete systems, COP calculations should include energy consumption of all power consuming auxiliaries. The COP is highly dependent on operating conditions, especially absolute temperature and relative temperature between sink and system, and is often graphed or averaged against expected conditions."
In short, a heat pump is more efficient when compared to using the energy to directly generate heat because it's more efficient to move heat than generate it.
> And pretty much everyone in the world (except those with central air) needs a couple of air conditioners now.
Absolutely not. Where I live we had 34°Ctoday but I would still never buy an A/C unit, which will ruin your health (heat/cold shock, bad air moisture levels, ...), waste immense amounts of energy and makes leaving the house a pain as the rest of the world becomes uncomfortable. Most of my friends here earn very well but I can't think of anyone that would see a reason to buy one. Live with the temperature and adjust - like the famous Iberian or Mexican siesta, where you simply accept that midday are low energy hours.
But even beyond this, the reason for A/C use is just bad architecture and city design. More trees in the streets can lower the temperature in the street itself and nearby residences easily by 1-2 degree. Less absorbing surfaces (asphalt, stone sidewalks, ...) make another difference.
And as regards the houses, there are plenty of ways for passive and energy efficient buildings that keep cool. In the middle east they have built self-cooling houses for centuries.
And in all this, even if you are stuck with bad streets and architecture, you can simply adapt, use efficient ways to keep cool (a fan can work wonders) and drink warm rather than iced drinks and your circulatory system will thank you as you don't switch regularly get shocked with 10-15° differences and you will sweat much less.
I'd been using a window unit for the bedroom but got sick of taking it in an out and decided to see how long I could manage without it. Now I prefer no air conditioning because of the reasons you state above - it feels much more comfortable being outside on hot days. I keep the windows and doors closed during the heat of the day then open them up when it's cooler outside than it is inside.
Let me guess, where you leave there are "serious" blinds outside the windows that help keeping sunshine out. I wonder when Central Europe will start installing them.
Patents, intellectual property, etc. It's why every appliance is trash nowadays. Big corps are IP holders, and there's only so many ways to engineer certain actions. Regardless even if you try to startup a company you'll be pushed out by the control big corps have over manufacturing.
We need to start nullifying IP if we ever hope to see innovation.
Probably not this, most IP can be worked around, and especially in the area of AC operations and thermodynamics, that hasn’t changed in almost a century.
Window units really only exist at all because of buildings that can't accommodate better designs for either practical or legal reasons. There's just no amount of innovation that can make it so that having the intake and the outtake right next to each other without a nearly perfectly sealed box on one side (ie. a fridge or a freezer) is gonna be anything but a big ugly noisy energy gobbler.
If you can't have central, you should have mini-split, and that's where all your problems get solved. If you can't get mini-split because your landlord won't let you drill conduit to outside then you're just kinda stuck and the laws of thermodynamics are your enemy, not a lack of innovation.
I don’t believe in breakthroughs anymore until I see a shipping product. I don’t care if you are a scientist, company, government agency, or NGO same thing applies.
Tell me you’ve made an incremental improvement and I’ll believe you, tell me you’ve made a breakthrough and either you’re lying or something will prevent it from being realized before commercial availability. This is what decades of press releases and articles that might as well be press releases have taught me.
The “save up to $500” in the presser is just so obviously fluff. $500 in what home?
And I suspect the magic here is also an air tight new construction home with a layout designed around this, not leaky everything with an old water heater tucked under the stairs, a 30 year old furnace, and R19 insulated walls.
Presumably the 30 year old furnace is replaced or supplemented with a new heat pump.
I have realized an approximately $500 yearly savings by replacing an older electric tank water heater with a hybrid electric (heat pump) water heater so I can believe that claim.
But there exist sooo many prototyping breaktroughs.
Those who follow press releases for many years know that just a tiny fraction can transfer this in real world products that actually work
(so many more challenges to overcome compared to prototype situations!! I don’t even know where to begin… every ground is different, average person doing the manual work is not as skilled and has less support engineers, the guys setting/defining the dimensions of various recipients/pumps/conduits are often undeskilled and the efficiency often lacks tremendously for that reason…)
My thinking on it is: It'd better work, they're just trying to catch up to the state of the art. The bigger news would be if Lennox CAN'T make a COP 2 at 5F heat pump. :-
I agree with the general sentiment, but the article explains that this "breakthrough" is a product prototype that meets a government spec. It's hyperbolic wording, but they're trying to warm people up to the idea of eventually getting a heat pump to alleviate some energy issues.
So 10k+ outlay to save under $500/year. That would take only 20+ years to pay off. The wall units are kind of flimsy. Expect at least one to break. And that $500 in savings is probably $300/year in reality. Its still a great option for some places, just not really to switch over from a gas furnace.
Seems more reasonable to compare the typical initial cost vs the increased initial cost for the higher efficiency unit that saves $500/yr.
My house was built in 2000 with a regular AC unit for the main floor and heat pump for the 2nd floor, both Payne, a builder grade of Carrier. The inside coil went first, at the 9-yr mark with a 10-yr warranty, so I did get a new coil at no expense but it cost $600 to install it.
A couple years later, the outside heat pump went out, and because of the system's age (about 11 years), they recommended replacing the furnace and heat pump.
A couple year later, the main floor furnace exhaust gas blower mechanism went out, and again, the outside unit was replaced because it was 14 years old.
In contrast, my previous house had an American Standard AC and furnace that was installed in 1970 when the house was built. I had to replace the furnace blower motor one year - about $500 I think - but the original AC and furnace were working like a champ when I sold the house in 2003.
In summary, you aren't getting 20 years out of any modern, shitty system anymore. They're designed to fail after 10 years. You might get lucky and have something fail after 9 years; then you'll only have to pay for labor. But because there are 2 major independent components, the outside compressor and inside furnace, it's unlikely they'll both fail within the warranty.
My AC guy told me the main reason they fail is because the new coils are made of very thin aluminum and so fail sooner than the old systems. If a coil fails, either in the furnace or the outside condenser, you're screwed. They can sometimes fix them, but good luck with that. Most HVAC dealers don't want to bother doing that; they just want to sell a new system.
Which is always the problem when you ignore the negative externalities. One would hope those externalities might start to be internalised to the cost of burning fossil fuels for heat, then heat pumps might become a better prospect.
(Tbh, I recently did a high level analysis of a heat pump in a temperate climate, and in light of climbing fuel bills and the potential for low price electricity from renewables at low demand plus batteries, heat pumps start to make a lot of sense. You need to think about using them differently to gas though)
I think it also ignores the fact that one of the big energy suppliers entered a war of territorial expansion and it may take a while until it's business as usual - I'd expect this to also affect energy prices.
The claims are pretty amazing. High efficiency, efficient over a wide range of temperature difference, high temperature differences possible.
The operating principle is totally different. It is based on acoustic waves. Not using phase-changes but just the ideal gas law (pressure and temperature are proportional). I tried to get my head around it, and I got it with a standing sound wave. But they use a traveling wave, for which I could not find explanations I understood.
The general idea is "lower air pressure and move gas to cold side so the gas heats up" followed by "raise air pressure and move gas to warm side so the gas cools down". That means the low pressure needs to be low enough that the gas gets colder than the cold side, and the high pressure needs to be high enough that the gas gets hotter than the hot side. Luckily that is 'just' a matter of amplitude of the sound wave. I think this is how they achieve their wide range of efficient temperature deltas.
That wide range is the main difference with a phase-change based unit. The phase change happens at a much more difficult to change temperature.
Really curious what kind of COP this technique can achieve. Cool tech if real, since it doesn’t need any refrigerant. Wondering if there are other downsides.
Non phase change systems are inherently more efficient because every heat exchanger (air/air, air/coolant and coolant/water) can be counterflow, allowing substantially greater efficiency.
In phase change systems, the 'hot side' and 'cold side' are all at the same temperature, which means any gradient in whatever you are heating/cooling is lost energy.
> The general idea is "lower air pressure and move gas to cold side so the gas heats up" followed by "raise air pressure and move gas to warm side so the gas cools down".
This sounds like Maxwell's Demon, where the work required to prevent the system from reaching thermodynamic equilibrium is equal to or greater than the extra energy. How does this differ from that?
Can you explain in more detail how it sounds like Maxwell's Demon? There's nothing that sounds like it sorts the air particles, so I don't see the connection.
Maxwell says that the effort you put in is more than the work you can get out. So the heat difference you get, even if converted perfectly to other kinetic energy, will always be less than the electricity input.
But we aren't after kinetic energy, or work. We are after heat.
I thought heat was a form of kinetic energy? Specifically, it is a measure of the kinetic energy of an object's particles, independent of the kinetic energy of the object as a whole. That not accurate?
Makes sense. I was thinking of it in context here. Seems the distinction between kinetic and thermal inside a heat pump is less useful that other places.
Counterarguments to Maxwell's Demon is not that such chambers with a microscopic door cannot be fabricated, but that the Demon and his door cannot run without some entropy/power source outside to the chamber thereby negating the "negative energy" created by it. The Demon works if you don't mind feeding him and maybe adding fuel to the chamber as well, but then you're not getting the supposed free energy.
This is how a refrigerator works. No it does not violate the "Maxwell's Demon" thought experiment. Yes it does consume electricity, it's not for free. Efficiency gains are still good though.
Another non-phase change method is the reverse Brayton cycle. Kind of like running a gas turbine in reverse. I think it is somewhat widely used in cryocooling, and in jet airliner cabin AC, but it seems to not have caught on for domestic heat pump applications. Presumably the traditional phase change approaches are more efficient in the relevant temperature ranges.
This makes me idly wonder if we could use those rays of golden sun for heating more efficiently than we are. Pitch black panels facing the sun through which you pump some heat-transfer fluid? Hooked up to a heatpump?
It can operate efficiently at lower temps. Current air source heat pumps see degraded performance and below freezing temps and will not be able to effectively heat a home at the lowest temps that can occur in the northern hemisphere.
The "secret sauce" of the increased efficiency is that they're using thermoacoustics, which previously had been a technology used in one-off applications with a large budget (e.g. the James Webb telescope uses it to stay cool). Prior to now there were no manufacturers providing the technology to be widely available at scale.
No idea how the Lennox units in TFA do it, but the Mitsubishi "hyper-heat" units do it by diverting a small amount of their output back into heating up the refrigerant at very cold temperatures. It starts to get a bit "slushy" at the low end of the performance range, which impacts the ability to move heat. By warming it back up to the bottom of its ideal operating range, the whole system functions more efficiently.
Yes; many EVs already use heat pumps, so if this has a higher coefficient of power (and is not much heavier), and it can be scaled down to automobiles, then it will be a win.
(None of those details can be inferred from the press release.)
But it delivers 100% words at 5°F at double the efficiency, and 70% to 80% words at -5°F and -10°F. DOE validated the performance and efficiency of the press release.
So much air in this statement, but almost zero raw numbers.
In the mean time, there are good quality air/water heat pumps on the market in Europe. Look at the Nibe F2120 for example. It blows this thing out of the water. It has a COP of 2.5 at -25C...
You really don’t. I’ve been in a house in Maine with spray foam in 20 degrees with no heat turned on and interior temp was around 65. It was pretty amazing actually.
A heat pump isn’t cost effective compared to Reno with spray foam. An average heat pump probably takes a decade minimum to pay off.
Spray foam is expensive. It’s considerably cheaper to install mineral wool or blown cellulose or fiberglass. And you can blow in insulation without removing the drywall.
> How does one blow in insulation without removing drywall?
We got blown insulation in the floors (ie between roof and floor), he drilled a 2 inch hole every two feet or so. We added our parquet floor right on top, with just some thin XPS sheets inbetween for noise.
Not sure about drywall, but I'd imagine it's similar. Easiest would be to just put some 6mm plasterboards on top to cover the holes, saves you handling each one individually.
You drill smallish holes in the drywall in each stud bay, blow the insulation in through the holes, and patch them. This is much less expensive and less messy than removing and replacing drywall. It can be done with cellulose insulation, with fiberglass (the loose fluffy kind, not batts), and possibly some other products.
Spray foam is expensive, but it pays for itself pretty easily. You can diy drywall hanging simply enough so you’re really just paying for the foam and someone to plaster, you can paint yourself.
A cheaper option is rigid foam with canned spray foam around the perimeter.
> The prototype delivers 100% heating at 5°F at double the efficiency, and 70% to 80% heating at -5°F and -10°F. DOE’s Oak Ridge National Laboratory validated the performance and efficiency of Lennox’s prototype.
Usually when people talk about efficiency of heat pumps they are comparing to electrical resistance heating (which is 100% efficient). If that's what they mean then they are saying 200% efficient at 5℉, which is not as good as Mitsubishi, which is better than 200% at 0℉.
But in the first paragraph they say:
> The U.S. Department of Energy (DOE) today announced that American heat pump manufacturer Lennox International became the first partner in the U.S. Department of Energy’s (DOE’s) Residential Cold Climate Heat Pump Technology Challenge to develop a next-generation electric heat pump that can more effectively heat homes in northern climates relative to today’s models.
It could be that they are stating efficiency compared to current heat pumps, not compared to resistance heating, in which case they would be claiming quite a bit higher efficiency than Mitsubishi, which would certainly justify calling it a breakthrough.
Another possibility is that what they could be claiming as the breakthrough is the 100% heating at 5℉ part. The Mitsubishi cold weather heat pumps start losing capacity below 23℉, falling from 100% at 23℉ to 76% at -13℉.
I don't think that would be as big a breakthrough as double the efficiency of current heat pumps, because it wouldn't make it so heat pumps are feasible in climates too cold for Mitsubishi. But it would make it so that in places you can use a heat pump you might not need as big of a heat pump with the new technology as you would need with a Mitsubishi. That could lower up front cost making converting from something else to a heat pump more feasible for many.
Mitsubishi's products seem to be mini-split systems[1].
--> EDIT: Or maybe not... they seem to offer forced-air too. <--
The DOE challenge is for ducted systems. Their site[2] says:
> The Challenge is currently focused on residential, centrally ducted, electric-only HPs.
The DOE challenge also has other requirements[3] that I don't know if the Mitsubishi systems satisfy. It requires certain levels of efficiency and "grid interactivity" (meaning Energy Star "demand response"[4] where your utility can temporarily tweak your thermostat settings).
I wonder why ducted systems were part of the requirements, is it because it's just aimed at the USA and then mostly at adoptability for existing systems (which seems to be ducted mostly)? I only have anecdotal experience and no numbers to back that up, but it's the only reason I can come up with that would put such a restriction in place.
I'd say rip the ducts out and just use split systems but I imagine other people have thought about that and figured it's not the best way to go. (or at last not in the US)
Yes, because nearly every house in cold climates is ducted, and we’re trying to get people off oil heating quickly, easily, and cheaply. Popping a new heat exchanger in an existing furnace is stupid simple compared to running coolant lines to new, wall-mounted exchangers all over the house.
I think that's true, if the ducts exist already that's simplest and cheapest. If they don't mini-split type systems are. But I suspect that long term those are going to be a pain in the butt because you have a lot of failure points.
Mini splits seem to be pretty reliable. They’re very common outside of North America. Most of the leading manufacturers seem to be from Japan (Mitsubishi, Fujitsu, Daikin)
Many of the Mitsubishi heat pumps work with central ducted systems just fine. I have one (replaced a central gas heat, electric AC system).
It’s just a different air handler but the heat pump was the same as would have been used in a mini-split install.
When cross shopping the Mitsubishi vs Trane, the Mitsubishi was miles ahead. I didn’t even get the most cold weather efficient option (not needed for my climate).
I see a few in Portland and several in nearby zip codes. Hopefully one can work for you. There are different tiers of “diamond” so you can compare if the difference matters to you.
One thing that’s a bit different is the air handler and outside compressor run on one circuit (mine is a 3 ton unit). So there’s a power line between the 2 units. That threw off our city inspector. But it works out nice since I now have an extra 20A breaker free :)
Thanks! Do you have the technical docs with the efficiency curves for the Mitsubishi ducted systems? I can’t find the materials amongst all the marketing.
I found it in their catalog. You’ll need your model or series. After all the specs there were some efficiency/temp tables. It was under Pros (vs homeowner) -> USA -> product support -> catalog -> m and p series.
For reference, here’s what we have: 36KBTU AIRHANDLER/HEATPUMP HI-STATIC M SERIES DUCTED SYSTEM
INDOOR MOD# SVZ-KP36NA
OUTDOOR MOD# SUZ-KA36NA2
It’s a slightly older model as we had height restrictions to work around. This prevented us from getting a newer or hyper heat model. IIRC ours had good efficiency into the 20F range which was plenty for us.
In comparison, the Trane dropped efficiency at 50F and needed heat strips at that temp (so pretty crap).
“Tapping into the emerging clean energy market is a huge economic opportunity that will bring a bolstered manufacturing sector, good paying jobs, and a brighter, cleaner future to Texas and communities across America.”
If anyone else is confused by this, it's because Lennox is headquartered in Texas.
what's not straight forward is understanding why the statement lists a single state and everyone else falls under 'communities across America' which the comment above clears up.
Lab vs typical observed performance differs quite widely for many home heating systems.
Thats because typically each appliance is tested at optimal conditions (eg. water flow rates). Then, in a real deployment, every parameter differs a little from optimal (eg. the water may circulate slower than expected because you have longer pipes around your home than the lab ones, and your hot water tank is hotter than expected because you like it set hot, and your airflow is less than expected because the filter is a bit blocked, etc.). Each knocks a few percentage points off the efficiency, but the overall impact can be dramatic.
We really need 'smarter' heating systems which can detect and correct for such things. For example, water and air pumps which measure temperatures and flow rates of air/water, and adjust speeds up and down to maintain the optimal efficiency point.
I wonder if the ideas used here can make low temperature geothermal systems more efficient. An example is the 760 kW system at Chena Hot Springs, 50 miles east of Fairbanks, Alaska. The system there uses hot water from said springs to generate power using repurposed refrigeration technology.
Chena Hot Springs geothermal is a heat pump. It's an absorption chiller used partially (primarily?) to keep an ice house chilled as a tourist attraction. It works for such relatively low geothermal temperatures because the average Carnot Delta T is pretty good (because Alaska).
As to whether or not thermo-acoustic technology could work, that's a good question.
At some point, it would be great to use a natural gas powered engine to run a heat pump. You could then use the exhaust gas as a heat source for the heat pump, possibly eliminating the need for a pre-heater.
Cooling the output should increase the Carnot efficiency of the motor.
Heating the outside air intake with that heat should be sufficient to avoid the need for an electrical resistance pre-heater.
This combination could also run on propane, ethanol, gasified wood, etc. Anything that gets burned now could be used to create far more heat output than straight up combustion.
There's got to be a flaw in this idea, math/physics wise.
Why would you create new technology with natural gas these days. It seems such an energy source of the past. Europe is jus suffering from the dependency on it and seeks to get away from it as soon as possible.
Agreed. Just electrify everything in the home, then while we still have natural gas then just use it for electricity generation. Natural gas's only benefit is that it is currently cheap, when that stops being true, then it is just worse than electricity across the board.
The great thing about electricity is that it scales REALLY well with new generation and distribution technologies.
So, you burn natural gas in a powerplant to create electricity somewhere around 55% (hopefully) efficiency; in most of the US, the heat output is wasted. You then lose 6% to transmission, getting to 52% efficiency, to put it into a 2x COP heat pump (which we mandate use gases with GWP in the thousands) to get 104% of natural gas heating.
Or, spend the same amount on air sealing reducing heating needs by about 30%, pay workers instead of factories, and get the same reduction in natural gas use, also without the refrigerant bomb waiting to go off, and not needing more power plants built. Mandate every rental have lower than 6 ACH50, since misaligned incentives mean they're usually worse than homeowner-occupied units.
Efficiency percentages are the wrong way to look at it. If you instead frame it in terms of tons CO2 equivalent, then locking in the emissions every year between now and 2050 is going to be worse, compared to the alternative of burning a bunch of natural gas for electricity now but gradually phasing it out in favor of wind and solar.
Europe is resource poor and suffering from a dependency on Russia.
55 billion cubic meters annually were set to be added to this dependency as recently as February 21st of this year before yet another land war erupted on the continent, forcing them to suspend certification.
The flaw is that we need to stop using fossil fuels now in order to meet Paris targets.
Natural gas in particular is an issue because demand is increasing globally whilst large suppliers i.e. Russia, Australia for many reasons are not able to meet it. Which is pushing up prices and increasing unreliability over the short, medium and long term.
Now is the best time to bite the bullet and transition to a decarbonised world.
I think you’re basically describing a steam engine that mechanically powers a heat pump, pumping it’s own waste heat and whatever environmental heat it needs.
It’s pretty complicated. Direct hearing via heat exchanger is usually pretty good and much simpler, albeit less efficient. If burning thermal sources, raw efficiency is rarely all that necessary though. The heat output per unit mass is usually pretty high.
Environmental impact or geopolitics issues aside, an electricity grid is much more convenient and cheaper than a propane/ethanol/gasified wood grid. Transporting gaz by trucks and storing it in individual houses is not very convenient too.
Apparently, all of us in the northern part of the US are supposed to build new houses that are super-insulated and run on renewable electricity. Which is a nice goal, but in the here and now, we've got a grid that couldn't possibly handle everyone going fully electric, and it's not reliable because most of it's above ground, where it'll stop working when we need it the most. (In the winter, when it gets icy, and power goes out)
All I'm suggesting is that we take an existing natural gas furnace out of service, and replace it with something that uses FAR LESS natural gas, with the same heat output to the home. It's not perfect, it it's better than what's there, and fits within the infrastructure in place.
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[ 2.1 ms ] story [ 309 ms ] threadLabor is expensive right now. :(
I set mine up with T's, electric dampers and some simple logic.
It's a bad system. Split systems make sense, and I know they exist, but they seem weirdly rare.
Some data on this topic: https://www.energyvanguard.com/blog/will-a-heat-pump-water-h...
I have the stats from my own Rheem to know I’m coming out ahead financially during winter and also haven’t seen a meaningful swing in the basement climate.
I’m a regular participant in that linked blog, too. :)
- the Canada premium: these sorts of things are just more expensive here. The base price was just higher than I could find in the US, but obviously importing is too expensive. I think the reason for this is there's almost no stock.
- adapting my house: the house I live in was built to have central air added to it, but even so the pipes going from the furnace room to the outside had to be insulated both directions instead of only one for an AC. Ripping up our basement ceiling to do this added a lot to the cost. An unfinished basement would help a lot here.
- HVAC company confusion: I had to go through like five HVAC companies before I found one that would believe me that I really wanted it. The one I got is a commercial outfit, so their prices were just higher. Even they were skeptical but they were willing to work with us, and by the end they talked about doing more installs so that was nice.
I think the cost for the install and unit itself was $12k for a top of line carrier unit capable of working down to pretty low temperatures. But we already had a compatible carrier furnace and exchanger. Was another couple thousand for ripping up the basement, which we had other contractors do.
This was also literally during the heat dome last year. They had to ship the unit across the country.
You can definitely do it for cheaper. There are $1000-$3000 single-head units available online for self-install, and you could hire an HVAC person to come out and do the high pressure line part of it (or all of it) for a similar range. It just gets expensive with the name-brand ones. For some reason that $2k-6k turns into 10k-20k when you switch to a name brand (e.g. mitsubishi). They're only available through specific installers, and using a non-authorized installer means your warranty is void.
Of course, a multi-room install would probably get expensive quickly here too.
[1]: https://kaiteki.no/
is this an announcement of a breakthrough or a challenge to find a breakthrough?
> The prototype delivers 100% heating at 5°F at double the efficiency, and 70% to 80% heating at -5°F and -10°F. DOE’s Oak Ridge National Laboratory validated the performance and efficiency of Lennox’s prototype.
> Lennox is one of nine manufacturers competing in the CCHP Technology Challenge. Its product and others that meet the CCHP Technology Challenge will undergo trials in cold climate regions over the next two years to demonstrate performance, efficiency, and comfort when applied in the field throughout a winter. Deployment and commercialization are planned for 2024.
Gree has a system that claims to have full heat down to -31, so I'd say just keep researching and you'll probably be fine.
Doing a quick search, they're using 'standard' R410A refrigerant (PDF):
* https://www.greecomfort.com/assets/our-products/multi-plus-u...
the same as everyone else. It seems just that they though it worth the engineering effort to push a little further than most other companies.
See anything with the label "For Extreme Conditions":
* https://www.greecomfort.com/our-products/
In my case, the 99% design temperature is high single digits Fahrenheit. For the 3.5 days/year colder than that, the plan is to have the house “coast” on thermal mass.
That’s for cases where the ambient temp is below design (where the heater can make heat but just no longer enough to keep up with the building heat loss), not for when it’s below a cutoff (where the heater shuts off entirely). In my case, that’s so far below design temp that I’d expect to never see it. (We hit -9°F in 2016 and would have to go all the way back to 1943 to find a low of -14°F.) If it happened, thermal mass would start to carry us with electric space heating keeping the house from totally freezing.
I'm planning on getting rid of it altogether and doing the heat pump(s) most of the year, the wood stoves in winter and reclaiming a lot of headroom in the basement and an entire utility room that the furnace currently takes up.
But, if you’re willing to wait or pay extra for the efficiency gains, you might be even better off getting set up with a ground source heat pump now. The install cost is more up front, but because ground temperature is higher than air temperature in winter and lower than air temperature in summer, the differential you need to pump in or out is a lot less, and therefore much more efficient. I don’t think any air to air heat pump in the next 20 years will be as efficient as a ground to air system you could install now. The air to air systems just have lower up front install costs.
Edit: it’s 26% this year and 22% next year.
One tip from my install, is to go with single zone units. I did a multi-zone and the way the control system works is kind of weird. They also don't have as good of a turndown ratio[0] as smaller/single zone systems, making it less efficient.
Overall I'm happy with it though.
[0] https://en.wikipedia.org/wiki/Turndown_ratio
A repair person goofed the settings last January, and I didn't notice the furnace wasn't kicking in until the end of February. My electric bill went from $150-ish for Feb 2021 to $450-ish for Feb 2022.
The release goes on to say they expect commercialization and deployment in 2024.
"Coefficient of performance" is a better term.
https://en.m.wikipedia.org/wiki/Coefficient_of_performance
So the ">100%" comes from the fact that you're spending less thermal energy than you are moving?
Even electric heat alone is 100% efficient no incomplete combustion or degradation over time. Efficient bu much more expensive than just moving heat already in the air.
Ground-source are better for now since they are moving heat from a relatively consistent source the Earth. It's about 15C to 25C one meter down where the ground-source heat pump lines are run.
Generating vs moving heat I think is misunderstood by people or really more likely they just don't care. As long as the bill is low!
Running a steam turbine by pushing water down a borehole to come into contact with a high-temp (>100°C) source has been done; it's not perpetual motion. Energy pumping the water is << energy output from the steam produced. It's solar energy that's being used, ultimately.
The 300% efficiency means if you had 1 Watt you could use it to power a fan and coolant lines to move heat. Or use 1 Watt to generate heat and then once made to move that heat.
The moving of heat already existing in the air (or in the ground) is more efficient than generating the heat and then moving it.
If someone asks: "how efficient is this heat pump at heating my house?" And you start digressing about how that's the wrong question to ask you'll be giving them an impression opposite reality, which is for most people: it will use less electric energy than heat energy it puts into your house, almost all the time.
I think a COP of 2 at 5°F (-15°C) is pretty good.
My new car can do 100% driving!
Surely not engineering way of thinking but that's a common heat pump metric for ordinary people.
So, 2 EER (2x of resistive heat) at 5F, 1.8 at -5F and 1.6 at -10F? Is that right? Seems awkwardly worded.
Yes (or double of previous model as another commentator points out-- hard to say).
> 1.8 at -5F and 1.6 at -10F?
They've not told us the efficiency-- just that it provides 70-80% of nameplate amount of heating at those temperatures.
They could choose the lowest temperature, find it's power input, then fix it at that amount. But at low temperatures the concern is usually less "efficiency" and more "am I going to freeze to death", because in most of the cold areas temperatures aren't usually that cold for that long (though in others it definitely is, and if you're running at 1.6 COP for a significant amount of time, you're better off with more insulation than a heat pump).
A COP of 2 @ 5F isn't a "breakthrough" vs. the first commercially available model I could find numbers for, and a COP of 1.5 at -10F seems implausible:
https://www.nordicghp.com/2017/01/heat-pump-effective-temper...
Honestly though, this press release is so poorly written, I wouldn't trust the numbers match up to anything.
Business wise, if this really works at 2COP at 5F, this might take over most of the market served by ground source heat pumps though.
Sure the "efficiency" is improving but it's mainly tricks for turning it on/off at better times. I know there are some U-shaped ones now, but it's just a slightly different styling.
Edit: two commenters pointed out examples of air conditioners which are 77 lbs and 56 lbs. As a comparison, the OSHA recommended lifting weight is 50 lbs. I would love to see someone apply Apple's obsession with thinner, lighter, "revolutionary new design" to ACs.
https://www.homedepot.com/p/Toshiba-14-000-BTU-12-000-BTU-DO...
[1] https://www.midea.com/us/air-conditioners/window-air-conditi...
No affiliation to Midea just a satisfied customer.
I have one in a room on the far end of the house that the main AC can't reach, it helps reduce power usage since I can keep the rest of the house warmer.
Edit: it might also be an issue of diminishing returns of better efficiency compared to how difficult it is to produce and maintain a better unit. Thermodynamics can be a pain like that.
EDIT: Oh lol, the unit we got was actually one of those Midea ones linked in a sibling comment.
The First Law of Thermodymamics.
Heat is work and work is heat
The Second Law of Thermodymamics:
Heat cannot of itself pass from one body to a hotter body
Heat won't pass from a cooler to a hotter
You can try it if you like but you far better not-a
'Cos the cold in the cooler will get hotter as a rule-a
'Cos the hotter body's heat will pass to the cooler
Heat is work and work is heat and work is heat and heat is work
Heat will pass by conduction and
Heat will pass by convection and
Heat will pass by radiation
And that's a physical law
Thermoacoustic refrigeration seems to be one of the more promising technologies but I would love to hear about others.
Interestingly, they aren't that loud because any sound lost is energy lost, so they try very hard to 'keep it quiet'.
Some areas (cough nyc cough) may need some regulatory breakthroughs but the technology is there.
Computers are actually a very special case. They don't really do any physical work in sense other stuff does, thus miniaturization gives lot of gains there. I have long said that small drones are answer to flying cars. We have them and they are small, but lifting people is hard work.
It's physics and thermodynamics. It's basically the same as with any heat engine, internal combustion engines included.
There is a certain maximum theoretical efficiency that is not 100%. When we build real machines (not theoretical ones) there are real world losses like heat loss, fluid flow friction, moving part friction, electrical inefficiencies, etc. Those real world losses van be gradually worked on over time, improved incrementally to yield small gains in efficiency. But never large ones, and never more than the theoretical max efficiency, which is not 100%.
It's like hybrid cars (not plug in hybrids, but just gas powered hybrids), they've doubled or trippled the mileage compared to a comparable regular car, but they will always need gas, they will never be 100% efficient.
Same with this. There will always be some fundamental electrical losses in the copper in the motor, air gap losses in the motor, friction in the bearings and fluid, heat losses to the environment, etc. It's the cost of doing the work. There is no free lunch, so we can only incrementally improve the little losses over time.
"The coefficient of performance or COP (sometimes CP or CoP) of a heat pump, refrigerator or air conditioning system is a ratio of useful heating or cooling provided to work (energy) required.[1][2] Higher COPs equate to higher efficiency, lower energy (power) consumption and thus lower operating costs. The COP usually exceeds 1, especially in heat pumps, because, instead of just converting work to heat (which, if 100% efficient, would be a COP of 1), it pumps additional heat from a heat source to where the heat is required. Most air conditioners have a COP of 2.3 to 3.5. Less work is required to move heat than for conversion into heat, and because of this, heat pumps, air conditioners and refrigeration systems can have a coefficient of performance greater than one. However, this does not mean that they are more than 100% efficient, in other words, no heat engine can have a thermal efficiency of 100% or greater. For complete systems, COP calculations should include energy consumption of all power consuming auxiliaries. The COP is highly dependent on operating conditions, especially absolute temperature and relative temperature between sink and system, and is often graphed or averaged against expected conditions."
https://en.m.wikipedia.org/wiki/Coefficient_of_performance#:....
More detail here:
https://physics.stackexchange.com/questions/489467/can-a-hea...
In short, a heat pump is more efficient when compared to using the energy to directly generate heat because it's more efficient to move heat than generate it.
Absolutely not. Where I live we had 34°Ctoday but I would still never buy an A/C unit, which will ruin your health (heat/cold shock, bad air moisture levels, ...), waste immense amounts of energy and makes leaving the house a pain as the rest of the world becomes uncomfortable. Most of my friends here earn very well but I can't think of anyone that would see a reason to buy one. Live with the temperature and adjust - like the famous Iberian or Mexican siesta, where you simply accept that midday are low energy hours.
But even beyond this, the reason for A/C use is just bad architecture and city design. More trees in the streets can lower the temperature in the street itself and nearby residences easily by 1-2 degree. Less absorbing surfaces (asphalt, stone sidewalks, ...) make another difference.
And as regards the houses, there are plenty of ways for passive and energy efficient buildings that keep cool. In the middle east they have built self-cooling houses for centuries.
And in all this, even if you are stuck with bad streets and architecture, you can simply adapt, use efficient ways to keep cool (a fan can work wonders) and drink warm rather than iced drinks and your circulatory system will thank you as you don't switch regularly get shocked with 10-15° differences and you will sweat much less.
We need to start nullifying IP if we ever hope to see innovation.
If you can't have central, you should have mini-split, and that's where all your problems get solved. If you can't get mini-split because your landlord won't let you drill conduit to outside then you're just kinda stuck and the laws of thermodynamics are your enemy, not a lack of innovation.
Tell me you’ve made an incremental improvement and I’ll believe you, tell me you’ve made a breakthrough and either you’re lying or something will prevent it from being realized before commercial availability. This is what decades of press releases and articles that might as well be press releases have taught me.
And I suspect the magic here is also an air tight new construction home with a layout designed around this, not leaky everything with an old water heater tucked under the stairs, a 30 year old furnace, and R19 insulated walls.
The "up to" part means it's the absolutely largest home you can possibly imagine
I have realized an approximately $500 yearly savings by replacing an older electric tank water heater with a hybrid electric (heat pump) water heater so I can believe that claim.
The announcement is basically: A US company (Lenox) has a prototype heat pump that matches performance of Mitsubishi and LG heat pumps.
The DOE is running a competition to get US companies to improve performance of their heat pumps.
But there exist sooo many prototyping breaktroughs.
Those who follow press releases for many years know that just a tiny fraction can transfer this in real world products that actually work
(so many more challenges to overcome compared to prototype situations!! I don’t even know where to begin… every ground is different, average person doing the manual work is not as skilled and has less support engineers, the guys setting/defining the dimensions of various recipients/pumps/conduits are often undeskilled and the efficiency often lacks tremendously for that reason…)
My house was built in 2000 with a regular AC unit for the main floor and heat pump for the 2nd floor, both Payne, a builder grade of Carrier. The inside coil went first, at the 9-yr mark with a 10-yr warranty, so I did get a new coil at no expense but it cost $600 to install it.
A couple years later, the outside heat pump went out, and because of the system's age (about 11 years), they recommended replacing the furnace and heat pump.
A couple year later, the main floor furnace exhaust gas blower mechanism went out, and again, the outside unit was replaced because it was 14 years old.
In contrast, my previous house had an American Standard AC and furnace that was installed in 1970 when the house was built. I had to replace the furnace blower motor one year - about $500 I think - but the original AC and furnace were working like a champ when I sold the house in 2003.
In summary, you aren't getting 20 years out of any modern, shitty system anymore. They're designed to fail after 10 years. You might get lucky and have something fail after 9 years; then you'll only have to pay for labor. But because there are 2 major independent components, the outside compressor and inside furnace, it's unlikely they'll both fail within the warranty.
My AC guy told me the main reason they fail is because the new coils are made of very thin aluminum and so fail sooner than the old systems. If a coil fails, either in the furnace or the outside condenser, you're screwed. They can sometimes fix them, but good luck with that. Most HVAC dealers don't want to bother doing that; they just want to sell a new system.
(Tbh, I recently did a high level analysis of a heat pump in a temperate climate, and in light of climbing fuel bills and the potential for low price electricity from renewables at low demand plus batteries, heat pumps start to make a lot of sense. You need to think about using them differently to gas though)
The claims are pretty amazing. High efficiency, efficient over a wide range of temperature difference, high temperature differences possible.
The operating principle is totally different. It is based on acoustic waves. Not using phase-changes but just the ideal gas law (pressure and temperature are proportional). I tried to get my head around it, and I got it with a standing sound wave. But they use a traveling wave, for which I could not find explanations I understood.
The general idea is "lower air pressure and move gas to cold side so the gas heats up" followed by "raise air pressure and move gas to warm side so the gas cools down". That means the low pressure needs to be low enough that the gas gets colder than the cold side, and the high pressure needs to be high enough that the gas gets hotter than the hot side. Luckily that is 'just' a matter of amplitude of the sound wave. I think this is how they achieve their wide range of efficient temperature deltas.
That wide range is the main difference with a phase-change based unit. The phase change happens at a much more difficult to change temperature.
https://en.wikipedia.org/wiki/Thermoacoustics
And, even from the perspective of field theory, aren't fields defined by the type of waves moving through them?
I don't think the fields are defined by their waves, but specific fields have specific wave patterns/types
In phase change systems, the 'hot side' and 'cold side' are all at the same temperature, which means any gradient in whatever you are heating/cooling is lost energy.
This sounds like Maxwell's Demon, where the work required to prevent the system from reaching thermodynamic equilibrium is equal to or greater than the extra energy. How does this differ from that?
But we aren't after kinetic energy, or work. We are after heat.
Your idea of 'kinetic energy of the object as a whole' is probably quite close.
https://www.youtube.com/watch?v=abswNCqnMRQ
(None of those details can be inferred from the press release.)
In the mean time, there are good quality air/water heat pumps on the market in Europe. Look at the Nibe F2120 for example. It blows this thing out of the water. It has a COP of 2.5 at -25C...
That's certainly a way to retrofit an older building, but you still need a heat pump.
A heat pump isn’t cost effective compared to Reno with spray foam. An average heat pump probably takes a decade minimum to pay off.
Serious question.. I'd have thought it not practical to remove the cap on the wall (and that's assuming you can access it from the attic).
edit: "top plate" is the term I couldn't remember. substitute for cap in my comment.
We got blown insulation in the floors (ie between roof and floor), he drilled a 2 inch hole every two feet or so. We added our parquet floor right on top, with just some thin XPS sheets inbetween for noise.
Not sure about drywall, but I'd imagine it's similar. Easiest would be to just put some 6mm plasterboards on top to cover the holes, saves you handling each one individually.
A cheaper option is rigid foam with canned spray foam around the perimeter.
> The prototype delivers 100% heating at 5°F at double the efficiency, and 70% to 80% heating at -5°F and -10°F. DOE’s Oak Ridge National Laboratory validated the performance and efficiency of Lennox’s prototype.
Usually when people talk about efficiency of heat pumps they are comparing to electrical resistance heating (which is 100% efficient). If that's what they mean then they are saying 200% efficient at 5℉, which is not as good as Mitsubishi, which is better than 200% at 0℉.
But in the first paragraph they say:
> The U.S. Department of Energy (DOE) today announced that American heat pump manufacturer Lennox International became the first partner in the U.S. Department of Energy’s (DOE’s) Residential Cold Climate Heat Pump Technology Challenge to develop a next-generation electric heat pump that can more effectively heat homes in northern climates relative to today’s models.
It could be that they are stating efficiency compared to current heat pumps, not compared to resistance heating, in which case they would be claiming quite a bit higher efficiency than Mitsubishi, which would certainly justify calling it a breakthrough.
Another possibility is that what they could be claiming as the breakthrough is the 100% heating at 5℉ part. The Mitsubishi cold weather heat pumps start losing capacity below 23℉, falling from 100% at 23℉ to 76% at -13℉.
I don't think that would be as big a breakthrough as double the efficiency of current heat pumps, because it wouldn't make it so heat pumps are feasible in climates too cold for Mitsubishi. But it would make it so that in places you can use a heat pump you might not need as big of a heat pump with the new technology as you would need with a Mitsubishi. That could lower up front cost making converting from something else to a heat pump more feasible for many.
--> EDIT: Or maybe not... they seem to offer forced-air too. <--
The DOE challenge is for ducted systems. Their site[2] says:
> The Challenge is currently focused on residential, centrally ducted, electric-only HPs.
The DOE challenge also has other requirements[3] that I don't know if the Mitsubishi systems satisfy. It requires certain levels of efficiency and "grid interactivity" (meaning Energy Star "demand response"[4] where your utility can temporarily tweak your thermostat settings).
---
[1] https://www.mitsubishicomfort.com/residential/new-products
[2] https://www.energy.gov/eere/buildings/cchp-technology-challe...
[3] https://www.energy.gov/sites/default/files/2021-10/bto-cchp-...
[4] https://www.energystar.gov/sites/default/files/ENERGY%20STAR...
I'd say rip the ducts out and just use split systems but I imagine other people have thought about that and figured it's not the best way to go. (or at last not in the US)
When cross shopping the Mitsubishi vs Trane, the Mitsubishi was miles ahead. I didn’t even get the most cold weather efficient option (not needed for my climate).
https://www.mitsubishicomfort.com/residential/products/ducte...
And that says it's compatible with some "hyper-heat" outdoor units. So apparently they do offer both.
https://www.mitsubishicomfort.com/find-a-contractor
I see a few in Portland and several in nearby zip codes. Hopefully one can work for you. There are different tiers of “diamond” so you can compare if the difference matters to you.
One thing that’s a bit different is the air handler and outside compressor run on one circuit (mine is a 3 ton unit). So there’s a power line between the 2 units. That threw off our city inspector. But it works out nice since I now have an extra 20A breaker free :)
For example this is the Carrier Infinity 24 we are considering. https://d1049ui2fjityy.cloudfront.net/userfiles/inriver/docu...
Catalog:
https://mylinkdrive.com/viewPdf?srcUrl=http://enter.mehvac.c...
pocket guide:
https://mylinkdrive.com/viewPdf?srcUrl=http://enter.mehvac.c...
It’s a slightly older model as we had height restrictions to work around. This prevented us from getting a newer or hyper heat model. IIRC ours had good efficiency into the 20F range which was plenty for us.
In comparison, the Trane dropped efficiency at 50F and needed heat strips at that temp (so pretty crap).
If anyone else is confused by this, it's because Lennox is headquartered in Texas.
Thats because typically each appliance is tested at optimal conditions (eg. water flow rates). Then, in a real deployment, every parameter differs a little from optimal (eg. the water may circulate slower than expected because you have longer pipes around your home than the lab ones, and your hot water tank is hotter than expected because you like it set hot, and your airflow is less than expected because the filter is a bit blocked, etc.). Each knocks a few percentage points off the efficiency, but the overall impact can be dramatic.
We really need 'smarter' heating systems which can detect and correct for such things. For example, water and air pumps which measure temperatures and flow rates of air/water, and adjust speeds up and down to maintain the optimal efficiency point.
As to whether or not thermo-acoustic technology could work, that's a good question.
Perhaps you were thinking of the absorption chiller that keeps the Ice Museum at the resort cold. That's a separate system.
Cooling the output should increase the Carnot efficiency of the motor.
Heating the outside air intake with that heat should be sufficient to avoid the need for an electrical resistance pre-heater.
This combination could also run on propane, ethanol, gasified wood, etc. Anything that gets burned now could be used to create far more heat output than straight up combustion.
There's got to be a flaw in this idea, math/physics wise.
The great thing about electricity is that it scales REALLY well with new generation and distribution technologies.
Or, spend the same amount on air sealing reducing heating needs by about 30%, pay workers instead of factories, and get the same reduction in natural gas use, also without the refrigerant bomb waiting to go off, and not needing more power plants built. Mandate every rental have lower than 6 ACH50, since misaligned incentives mean they're usually worse than homeowner-occupied units.
Wind and solar also lock in natural gas usage, because they don't provide inter-seasonal storage or even intra-day storage.
55 billion cubic meters annually were set to be added to this dependency as recently as February 21st of this year before yet another land war erupted on the continent, forcing them to suspend certification.
The pipeline is already built though.
The flaw is that we need to stop using fossil fuels now in order to meet Paris targets.
Natural gas in particular is an issue because demand is increasing globally whilst large suppliers i.e. Russia, Australia for many reasons are not able to meet it. Which is pushing up prices and increasing unreliability over the short, medium and long term.
Now is the best time to bite the bullet and transition to a decarbonised world.
It’s pretty complicated. Direct hearing via heat exchanger is usually pretty good and much simpler, albeit less efficient. If burning thermal sources, raw efficiency is rarely all that necessary though. The heat output per unit mass is usually pretty high.
Environmental impact or geopolitics issues aside, an electricity grid is much more convenient and cheaper than a propane/ethanol/gasified wood grid. Transporting gaz by trucks and storing it in individual houses is not very convenient too.
Personally I’ve seen them use when there are large air conditioning loads but insufficient electrical power
https://www.yanmar.com/global/energy/ghp/
All I'm suggesting is that we take an existing natural gas furnace out of service, and replace it with something that uses FAR LESS natural gas, with the same heat output to the home. It's not perfect, it it's better than what's there, and fits within the infrastructure in place.
This isn't a technology breakthrough, this is a DOE policy/partnership/funding "breakthrough".