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How a heat pump works

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Re: How a heat pump works

#321

Post by bruckie »

coryrc wrote: post #311
bruckie wrote: post #170

Earlier quoted context omitted.

My parents installed a whole home humidifier a couple of years ago. It cost way more than $300 (closer to $2k installed—maybe they just got the wrong one?), and it also costs a lot to operate each month in additional electricity usage. Having a system that doesn't require one sounds much nicer.

I think you got confused with DEhumidifier. Humidifiers are cheap to operate.

Nope. It's a humidifier that uses resistive heating to vaporize water, and that takes a lot of energy.

Re: How a heat pump works

#322

Post by timbit42 »

bilsbie wrote: post #107
boringg wrote: post #7

What is going on? Is there a global push to get everyone to switch to heat pumps. It seems that there is heat pump content everywhere. Clearly there is a push. I understand that its for climate benefits but it feels very coordinated. edit: didn't realize the attention I would get. Let me add someone answered my question -- a good product market fit and people talking is probably where the push came from. That said HV…

Easier to turn off people’s electric than gas when they don’t follow the social rules.

Not when they have solar.

Re: How a heat pump works

#323

Post by timbit42 »

robotpony wrote: post #239
gwbas1c wrote: post #53

Earlier quoted context omitted.

Generally, they can work anywhere in the continental US. (Assuming you live in the US.) If you're in northern NH, NY, VT, or Maine, you might want to keep your gas system as a backup. (New homes tend to have electric backup, but if you have an older home they just keep your furnace as backup.) I have a 3000 sqft house in MA with a heat pump as my primary heat, and an electric strip as backup. The heat pump goes into…

Around Vancouver our heat pump has performed adequately even down to -15C/5F. This may be related to it being a deep ground loop geothermal setup (vertical instead of horizontal), and the type of building (concrete). We do have a gas fireplace as backup, but have not needed it at the temperatures we see in this corner of the world.

It is definitely related to it being a deep ground loop geothermal setup. An air-to-air heat pump is trying to get heat out of air that has less heat as it gets colder. A ground loop heat pump is trying to get heat out of water that is not affected by the temperature of the outside air.

With an air-to-air heat pump, you need a backup system for when it gets too cold out for the heat pump to pull enough heat out of the air, and for power outages. With a ground loop heat pump, you only need a backup system for when the power goes out because the ground water will never be too cold for the heat pump to pull heat out of.

Re: How a heat pump works

#324

Post by timbit42 »

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…

Heat pumps aren't meant to be turned on and off. In fact, they aren't meant to have the thermostat changed either, even at night. You set it to what you want and it keeps it there. Once it gets the temp where you set it, it doesn't use much electricity to keep it there unless it is very cold, like below freezing and especially below -20C.

Due to your high ceilings, it might be prudent to install ceiling fans to help circulate the heat, but I'm not a heating expert so I recommend asking one.

Re: How a heat pump works

#325

Post by timbit42 »

asow92 wrote: post #73
prottog wrote: post #57

Earlier quoted context omitted.

In the Northeast with that much square footage, you would be better off with ground-source heat pumps (whether open or closed loop), rather than the normal air-source heat pumps.

I guess the concern I have with all this is that my current system works well, and I don't want to spend $10K+ unless it brings down my heating costs significantly. Could a ground-source heat pump system do that?

A typical air-to-air heat pump has a CoP of 4 but the CoP goes down with the outside air temperature until the CoP becomes 1 at around -20C. Below that temp, you're better off using a backup heat source.

A ground-source heat pump typically has a CoP of 5 but the CoP doesn't go down with the outside air temperature. Because the ground water temperature is stable, it will maintain its efficiency when it is cold outside. Of course, depending on the R value of your house, it may need to work harder to make up for the heat loss through the walls, roof and windows.

You really need to find a heat pump installer who has the year round temperature data for your area and can do the math to calculate whether it is worthwhile to spend the extra on a ground-source heat pump.

Re: How a heat pump works

#326

Post by timbit42 »

vladgur wrote: post #288

Is there a good calculator where I can enter my cost for units of electricity and gas and it will tell me how much operating a heat pump will save me over a gas furnace

To get a useful answer, you would have to put in more information. How many floors? How many sq ft per floor, what is the R value of your house? How cold can it get in the winter? How often is it that cold? Are you asking about air-to-air or ground-source heat pumps? The best thing to do is to get one or more local installers to give you an estimate.

Re: How a heat pump works

#327

Post by timbit42 »

rr888 wrote: post #140

I just dont like moving parts. My problem with heat pumps is that you have to replace every 10-20 years which seems wasteful.

My heat pump has a CoP of 3 and paid for itself in 10 years. New heat pumps have a CoP of 4 or higher and might pay for themselves in less.

How much material in a heat pump is recyclable and how much isn't, compared to a furnace?

We are trying to reduce CO2 and methane in the atmosphere. Throwing away the non-recyclable parts of heat pumps isn't as big of a concern. Polluting the ground and water isn't even as big a concern. Certainly they are concerns, but they pale in comparison.

Re: How a heat pump works

#328

Post by photon12 »

brianaker wrote: post #314
photon12 wrote: post #283

Earlier quoted context omitted.

I put in a new Mitsubishi Hyper-Heat heat pump last summer. It got down to 17 Farenheit in Seattle this winter. There are no heat strips or supplementary heating arrangements. The heat pump performed well the entire winter. My energy bills are 1/2 of what I was paying with an electric furnace last year.

I too live in Seattle and have friends who bought a heat pump; they ended up in a hotel room and until they could had a HVAC company come to their home and install a backup heat source. In Seattle are highest usage months for electrical is in the winter, right when you will be maxing out that 50A breaker you had to install in order power that beast; check the notes from Mitsubishi, they are clear that it is not an ef…

"Mitsubishi Hyper-Heat, which I believe is only installed as a mini-split"

It's not a mini-split.

Re: How a heat pump works

#329

Post by coryrc »

bruckie wrote: post #321
coryrc wrote: post #311

Earlier quoted context omitted.

I think you got confused with DEhumidifier. Humidifiers are cheap to operate.

Nope. It's a humidifier that uses resistive heating to vaporize water, and that takes a lot of energy.

That's like cautioning about the price of cars because you bought a Hummer instead of a Corolla. Drum humidifiers use a couple watts on any central forced-air system.

And, since the heating season is there only time you need humidifying on this context, all the "waste" heat is just heating your home.

Re: How a heat pump works

#330

Post by kortilla »

mikeyouse wrote: post #204
kortilla wrote: post #193

Earlier quoted context omitted.

“Solution is bad when you don’t do it!”

Is it a "solution" when it's completely optional and rarely done correctly? This whole discussion reminds me of the 80s TV interviews that made the rounds this week about people complaining the government was infringing on their right to have a beer in the car on the way home from work ( https://www.tiktok.com/@cali_nostalgia/video/719704298970805... ). "It's my god given right to poison my family with CO and NOx!"

> Is it a "solution" when it's completely optional and rarely done correctly?

Yes, because it fucking works. This isn’t some network effect thing where everyone has to do it correctly.

It’s like saying diet & exercise isn’t a solution to obesity because it’s completely optional and rarely done correctly. Absolute stupidity.

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