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Heat Pumps – The Well-Tempered Future of A/Cs

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Re: Heat Pumps – The Well-Tempered Future of A/Cs

#311

Post by superq »

notyourwork wrote: post #303
doctorhandshake wrote: post #291

Earlier quoted context omitted.

This comports with my experience pricing out a similar sized mitsu system

Not sure if it's a bit over-priced, however, we replaced a gas furnace without A/C. The variable speed air-handler is amazing for constant low speed circulation and the energy savings with moderate temperature for 60-75 degree weather is incredible. Also, I have 15k BTU available for one or two additional head units. I opted for this approach instead of under-sizing the heat pump or assuming we'd need the extra head…

Your temperature controls are dependent on a "Kumo" cloud? that's rather terrifying. What if your internet goes out, or what if the cloud gets attacked (or your smart device)? Does that mean you lose control of your climate control?

Re: Heat Pumps – The Well-Tempered Future of A/Cs

#312

Post by gooseyman »

nsxwolf wrote: post #301
newZWhoDis wrote: post #224

Earlier quoted context omitted.

Almost certainly. Proper/modern heat pumps do not need heat strips until -20F or so

Chicago, so those low temperatures are achievable.

My understanding is that heat pumps operate at less than 100% efficiency at those levels. They don’t start blowing cold air, rather the air isn’t 90 degrees coming out any more.

Re: Heat Pumps – The Well-Tempered Future of A/Cs

#313

Post by stephen_g »

mft_ wrote: post #305
NiloCK wrote: post #283

Earlier quoted context omitted.

I have new heat pumps in a very old, under insulated, and leaky house. I didn't use my oil furnace last winter (the first since two additional pumps). My costs were about half of the previous year, and I'm sure my carbon footprint was much better as well. Can you say more about what your comment is supposed to mean?

Our house (in Europe) is relatively old and not well insulated by modern standards, and all of the advice we read and receive from experts is that heat pumps are not a good fit without additional insulation. The gist is that we’d need to spec larger units and/or run them harder than usual, removing savings vs. gas.

The usual other option is to look at increasing the size of the radiators, then you can lower the flow temperature and you still get big efficiency savings.

Re: Heat Pumps – The Well-Tempered Future of A/Cs

#314

Post by Alupis »

tcfhgj wrote: post #242
Alupis wrote: post #194

Earlier quoted context omitted.

> Yes you are, your natural gas subsidized, i.e. government handout, i.e. you're not paying the real market cost. > Your energy grid is shit, which is why your electricity price is so high. Adding a heatpump solves this issue, or makes it worse?

Heat pumps power consumption can be modulated by energy providers and improve grid power stability. In Germany you get way cheaper electricity prices if you allow this.

I am not aware of any such system in the US.

What do you mean by "modulate"? Your utility provider decides how much heat your home gets? That's a very strange concept.

Re: Heat Pumps – The Well-Tempered Future of A/Cs

#315

Post by stephen_g »

simonblack wrote: post #142
jillesvangurp wrote: post #97

Earlier quoted context omitted.

This persistent myth just needs to go away. People use heat pumps all over Scandinavia, including in the arctic circle. They are extremely popular there. They were early adopters of this technology there decades ago. There are two popular varieties: - Ground source heat pumps. Those work pretty much anywhere; just dig below the perma frost and you are good to go on the northern tip of Canada, Alaska, Norway, or where…

Ditto Australia. We've been using 'reverse-cycle air-conditioners' for heating in Australia for decades. I'm puzzled as to why there is any debate at all on their use for heating. A heat-pump is far more efficient for obtaining heat than direct resistive heating using electricity. Many houses here use no other form of heating at all. And then at the press of a button, we get cooling in summer too. What's not to like?…

Yes. Although I have noticed that some people here in Australia go from the belief that "air conditioners use a lot of electricity" so therefore have the misconception a (resistive) electric heater must be cheaper to use than the reverse cycle AC (heat pump). So there is a bit of an education gap even here where they are quite ubiquitous!

I also do want to get a heat pump dryer (it's next on the list after my recently installed heat pumper hot water system), but I don't have quite enough space in the laundry and apart from two or three wet weeks a year I'd mostly only use it to fluff up towels (which is why I don't have a dryer at all at the moment)...

Re: Heat Pumps – The Well-Tempered Future of A/Cs

#316

Post by stephen_g »

lsaferite wrote: post #184
simonblack wrote: post #142

Earlier quoted context omitted.

Ditto Australia. We've been using 'reverse-cycle air-conditioners' for heating in Australia for decades. I'm puzzled as to why there is any debate at all on their use for heating. A heat-pump is far more efficient for obtaining heat than direct resistive heating using electricity. Many houses here use no other form of heating at all. And then at the press of a button, we get cooling in summer too. What's not to like?…

I've seen heat-pump base water heaters, but never a clothes drier. That sounds interesting. Now I have something new to research, thanks! Personally, I'm always curious why there isn't a more unified heat-exchanger system built into the structure of a house. HVAC, Water, Refrigerator, they all need to move heat from one place to another, why not work together?

I've tried to make the idea work in my head many times but my conclusion has been that I don't think there's quite enough co-incident demand for heating and cooling in the average house. For example, yes, I could generate all my domestic hot water from heat from air conditioning in summer, but in winter I need to be able to generate it plus heat the house, so I need enough capacity to generate that heat from the outside air when I'm not using air conditioning (so I don't save on not needing as much capacity), and the efficiency gains probably aren't worth the extra complexity.

For applications like commercial buildings, public swimming pools, industrial sites, etc. can (and increasingly do) definitely benefit from that kind of combination though.

Re: Heat Pumps – The Well-Tempered Future of A/Cs

#317

Post by xyzzyz »

rayiner wrote: post #265
newZWhoDis wrote: post #224

Earlier quoted context omitted.

Almost certainly. Proper/modern heat pumps do not need heat strips until -20F or so

They need them installed (and the extra dedicated 240v outlets, which can get expensive) for defrost cycles which happen below 35F or so.

Depends on whether they are reversible or not. Reversible ones, which can act as AC in summer, simply reverse themselves and act briefly as AC, essentially using heat taken from inside the house to defrost themselves. Only a little heat is needed relative to heat capacity of a warm house. Mine does that. However, it still has resistive heating strips for emergency heating and for when the temperature falls too low for it to keep up.

Re: Heat Pumps – The Well-Tempered Future of A/Cs

#318

Post by windexh8er »

nsxwolf wrote: post #301
newZWhoDis wrote: post #224

Earlier quoted context omitted.

Almost certainly. Proper/modern heat pumps do not need heat strips until -20F or so

Chicago, so those low temperatures are achievable.

I have a 4 ton air source heat pump. It has both an internal heater and will run a defrost cycle by using the furnace in winter. I put in the full system a couple years ago. The entire system (100k BTU high efficiency furnace with variable output and 48k BTU, 22 SEER2 and 10.5 HSPF2) and the entire system was less than $17k. I also got over 4k in rebates (fed, state and manufacturer).

I'm well north of Chicago. The heat pump is rated to -22F but have the lockout set to 15F to cut over to the furnace. Mostly for wear and tear reasons. But it has a COP rating of 1.75 at 5F. So still more efficient than any furnace well below where I run it.

Re: Heat Pumps – The Well-Tempered Future of A/Cs

#319

Post by unscaled »

cornstalks wrote: post #4
nottorp wrote: post #3

Isnt any a/c a heat pump though?

Yes, but typically “heat pump” is used to mean it can provide heating too, whereas standard “A/C” is a “one-way” heat pump that only provides cooling.

It feels like very much a could country / could region distinction. In warmer regions of the world, heat pumps have been using for efficiently heating in winter since the 1980s (that's as far as my memory goes). Of course, when the temperature rarely went below 0℃. If you look at the single-room AC units that now dominate these markets, you'll rarely find anything that cannot do both heating and cooling.

Re: Heat Pumps – The Well-Tempered Future of A/Cs

#320

Post by kondor6c »

pkaye wrote: post #202
Maxion wrote: post #185

Earlier quoted context omitted.

It's just the Yanks that have subsidised natural gas in many states, and a messed up energy infrastructure that gives electricity prices in the same range as what we have in Europe while being at war.

I was trying to find heat pump adoption rates for Europe and US. Seems like its still pretty low in Europe outside some northern countries. Germany is less than 2000/100000 people. https://www.theecoexperts.co.uk/heat-pumps/top-countries Meanwhile this link says US has a 15% adoption rate across all income groups. That seems higher than I expected. https://energypost.eu/u-s-heat-pump-adoption-is-evenly-sprea... Is th…

Not a source, but it's more common to have heat pumps in the southern States where winters aren't that bad. I'm born and raised in Arizona and they seemed to be common in houses after the 1973 energy crisis. My grandparents house in Tempe, AZ (was built in like 1950's) did no have one. A house I purchased in central North Carolina had a heat pump. I'm now around Washington DC area in Virginia, and we has gas. I think a simple explanation is that natural gas is almost a by product (certainly from landfills, which is how most USA disposes of trash) and is very cost efficient. Also the energy crisis changed the outlook of house building. I hope that helps explain it some, sorry I don't have any concrete facts I'm typing on a small keyboard.
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