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How a heat pump works

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Re: How a heat pump works

#301

Post by qubitcoder »

nkurz wrote: post #285
rgmerk wrote: post #277

Earlier quoted context omitted.

88% of US households already have heat pumps, and 66% of households have centralised heat pump systems - otherwise known as air conditioning. If you can afford to have them just for cooling, you can afford to have them for heating as well; in fact, the capital cost may well be lower if people just used their air conditioning systems to heat as well. The same goes for reliability - we manage to make air conditioning a…

Wow, I was going to doubt your figures, but you seem to be right: https://energyathaas.wordpress.com/2022/08/15/how-many-u-s-h... I've lived all around the US, and don't think I've ever lived anywhere with central air. Well, that's not quite true: in New Mexico I had a roof mounted swamp cooler, but that's evaporative cooling and not a heat pump. Elsewhere I've occasionally had and used a portable compressor unit, bu…

I didn't quite grasp there was anything other than central air until recently in life (approaching 40). It's been the same everywhere I've traveled and lived across the US. I recall my grandmother's house having a gas floor furnace, which came in handy once during a blizzard.

I was surprised when a colleague from Minnesota who moved to the south mentioned never having air conditioning. I'd expect that in many parts of Europe. And I've sweated it out while living there, but it's extremely rare in my experience in the United States.

I've always had central air, along with a gas fireplace for emergency heat which, thankfully, I've never had to use.

Re: How a heat pump works

#302

Post by billiam »

The other issue here in SF and near the coast is that for older, poorly insulated homes and those with high ceilings (mine are 12 feet), the real problem with an air heat pump is how slow it is to heat the volume. Unless you want to pay to keep your house warm 24-7 it will take an hour to warm up the whole house. I would love to kick my 10 year old forced air gas furnace to the curb, but I don't see how, even if I get solar. Contractors are charging a fortune for installing heat pumps these days too.

Re: How a heat pump works

#303

Post by rapsey »

gautamcgoel wrote: post #299
rapsey wrote: post #43

Earlier quoted context omitted.

I guess they are a new thing in the US. In Europe installing a heat pump with floor heating is done for practically every new family house. It is the cheapest (for us) and nicest way to heat up your home. Though very few people build houses out of wood, unlike the US.

What are the houses usually made of? Stone?

Engineering/perforated bricks mostly. North Germany/UK is a lot of solid red/gray bricks, not sure if new homes still use that style, since it has terrible insulation. If built with perforated bricks a home will also put a thick layer of styrofoam for insulation on the outside.

Re: How a heat pump works

#304

Post by fragmede »

billiam wrote: post #302

The other issue here in SF and near the coast is that for older, poorly insulated homes and those with high ceilings (mine are 12 feet), the real problem with an air heat pump is how slow it is to heat the volume. Unless you want to pay to keep your house warm 24-7 it will take an hour to warm up the whole house. I would love to kick my 10 year old forced air gas furnace to the curb, but I don't see how, even if I ge…

But, at 3x the efficiency of a traditional gas furnace, it may still be cheaper to heat the house all day, or have it start heating at 4:30 pm.

Re: How a heat pump works

#305

Post by raldi »

molsongolden wrote: post #270

Calvin (Segment) and Baker (Plaid) also recently put together a nice up-to-date heat pump info page and a heat pump vs. existing HVAC calculator. https://heatpumpshooray.com/ https://calv.info/heat-pumps

What do you mean by Segment and Plaid?

Re: How a heat pump works

#306

Post by nicpottier »

peterhunt wrote: post #279
nicpottier wrote: post #184

Earlier quoted context omitted.

This is FUD. I live in climate zone 5 in a 100 year old house that has high heating demands and our air source heat pump has been awesome, even when it dipped into the negatives briefly this year. Our heat pump is over 100% efficient down to 0F.

What type of heat pump do you have out of curiosity?

Mitsubishi HyperHeat

Re: How a heat pump works

#307

Post by kaveet »

raldi wrote: post #305
molsongolden wrote: post #270

Calvin (Segment) and Baker (Plaid) also recently put together a nice up-to-date heat pump info page and a heat pump vs. existing HVAC calculator. https://heatpumpshooray.com/ https://calv.info/heat-pumps

What do you mean by Segment and Plaid?

Calvin French-Owen is the founder of Segment and Baker Shogry was Head of Product at Plaid until recently.

Re: How a heat pump works

#308

Post by jondiggsit »

ryantgtg wrote: post #275
Casteil wrote: post #222

Earlier quoted context omitted.

He does, but he omits a lot of important considerations that make heat pumps impractical for normal Americans. If he touches on them, it's briefly - if at all, e.g.: - More expensive units, and more expensive to run power wise. It's always difficult to get adoption of new technology that's "better" but more expensive to buy & repair - to the point where RoI may never happen. - Power grid implications during very low/…

Just to soften a few of your confident declarations. > normal Americans Please revise this phrase. America consists of many different climates and it's very unclear what you mean or why you chose the word "normal." > More expensive to run power wise You're comparing new gas HVAC vs new heat pump. However, don't forget about all the folks that are purchasing a heat pump to replace an existing gas unit! For example, my…

Mitsubishi Hyperheat…. Works at 100% capacity to -5f

Re: How a heat pump works

#309

Post by ASalazarMX »

ASalazarMX wrote: post #227
pkulak wrote: post #136

Earlier quoted context omitted.

I just found this guy too. He answered a lot of questions I had about efficiency and use below freezing. https://youtu.be/fxEqVuiHhM0

Can't recommend this channel enough, it's like the Captain Disillusion of home appliances. The video about hurricane lamps was the first I saw, and it solved questions I didn't know I had about their weird shapes.

Disregard my comment, I thought that guy was Alec Watson of Technology Connections.

Re: How a heat pump works

#310

Post by abdullahkhalids »

liminalsunset wrote: post #300
vladgur wrote: post #287

I live in SF Bay Area 20 minutes south of SF and I don’t have and don’t need A/C, so my HVAC needs are met by a gas furnace that is 10-15 years old at this point but it still works. Another caveat is our electricity ranges from 30 to 35 cents per KWh and is probably second to Hawaii in terms of cost. So I do check the cost of operating a Heatpump in the winter and due to high cost of power I am sticking with our gas…

TL;DR a heat pump isn't worth it in Vancouver, BC, for me anyway. As a counterpoint to what seems to me like extremely high rates for electricity, as of right now in Vancouver, BC, Canada, I recently calculated that a heat pump would cost about ~2.5-3.5 cents per kWh of heat energy vs ~4.5 cents for gas heating at 80% efficiency. Power on average is about $0.10 USD per kWh here and gas is about $10 USD per GJ. The av…

Do your calculations include the changes in utility prices?

I don't know if this is the right place to look at, But over the last 30 years, in BC, the "Electric power selling price under 5000kw index" has gone from 56.8 to 120.9, about an increase of 110%.

[1] https://www150.statcan.gc.ca/t1/tbl1/en/tv.action?pid=181002...

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