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How a heat pump works

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Re: How a heat pump works

#61

Post by PragmaticPulp »

notdarkyet wrote: post #34
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…

I see this as well and it looks to be multiple people buying in to the campaign, especially here on HN. Having lived in a new, high end apartment that had a heat pump for both heating and cooling for 3 years, I am very unimpressed with the tech. Running nonstop, couldn't heat/cool above/below a certain threshold. Electric bill very high. Clogged and broke a lot. If the general radiant heat and cooling from being in l…

Your singular experience is an outlier, not an example of totally normal circumstances.

There is no conspiracy to push broken technology on to the masses. Heat pump technology has come a long way and modern heat pumps are very good at what they do.

If someone installed a heat pump that doesn’t work in the temperature range of your location, they really screwed up. Modern heat pumps can be selected to work down to very low temperatures, and they’re installed with auxiliary heat when necessary. The design parameters aren’t a mystery.

Re: How a heat pump works

#62

Post by kevstev »

Bhilai wrote: post #26

Definitely a lot of posts about heat pumps on HN recently that this topic has piqued my interest but only to the point that I want to know if I can install one in my home. Are there any legit resources out there that can help me understand if heat pump is a right choice for my home based on Geo, type of home, sqft and other factors to consider before replacing current systems (two ACs and two furnaces?)

If you already have a central AC system, a heat pump is more or less a drop in replacement. The heat pump becomes both your heat and AC unit.

Heat pumps are now the most premium option on units offered by the well known names in HVAC- Trane, Carrier, etc.

In terms of suitability for your climate, they should work just fine for most people- they start to struggle if you are in an area when temps get down to about 10 degrees Farenheit, though they improve in this area each year. Even if you live in an area that cold, there are options to mitigate this- leaving your current furnace hooked up to be turned on during those cold periods, etc. What it comes down to is it just gets more expensive if you live in these colder areas, but over time the energy savings should give you a return on your investment in less than ten years.

My Air conditioner blew this fall, so I am actively in the process of getting bids for heat pumps.

Re: How a heat pump works

#63

Post by generaltsos »

manigandham wrote: post #47
generaltsos wrote: post #11

Earlier quoted context omitted.

That channel is fascinating. They have created some incredibly interesting projects.

What have they created? You might be thinking of Tech Ingredients - https://www.youtube.com/@TechIngredients

You're spot on - I am subscribed to both so I confused them without opening any links. Technology Connections is fascinating in its own right as well.

Re: How a heat pump works

#64

Post by bcrosby95 »

Maxburn wrote: post #33
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…

YES. There is a massive electrification push right now because electric items can be fed from "sustainable" things like wind/dam/solar and don't emit CO or CO2 in operation. Heat pumps are also inexpensive on initial cost and less expensive than straight AC with gas heat. They are also low maintenance in comparison to straight AC with gas heat. Very popular units in southern US.

This hasn't been my experience. I can get an AC unit and gas furnace installed for something like 7k. But a heat pump unit that heats and cools is something like 13k installed. I obviously went with the former.

Re: How a heat pump works

#65

Post by gabrielhidasy »

nashashmi wrote: post #16
nicoburns wrote: post #9

Earlier quoted context omitted.

> Is there a global push to get everyone to switch to heat pumps. I mean, yes. They're much more energy efficient than the alternatives and will play a key part of removing our dependence on fossil fuels. > I understand that its for climate benefits but it feels very coordinated. That seems like a good thing?

They are not more energy efficient than burning gas. Edit: since i am getting downvoted to oblivion, let me fight back here. I genuinely wished heat pumps would be more efficient and in theory they can be. I would love to not generate heat and just use the outside heat energy and compress it down into a smaller location. But compressing and decompressing is not an energy efficient task. It takes a lot of work. Mechan…

They literally are more efficient than burning gas, a good heat pump can do over 300% efficiency (KWs of heat in your house vs KWs of electricity used) while a furnace can only hope to get 100%. Even if the heat pump is fed from gas power plants (which burn gas with about 50-60% efficiency, more if the waste heat is reused), they are still using less gas for the same amount of heat than directly burning it.

Re: How a heat pump works

#66

Post by fullstop »

prottog wrote: post #60
fullstop wrote: post #45

Earlier quoted context omitted.

Your high end apartment must have had a low end heat pump installed. In the midwest a geothermal heat pump would work wonderfully. Also, they are designed to run constantly in order to maintain the set temperature -- it's not like a natural gas fired furnace where it quickly reaches the set point.

> Also, they are designed to run constantly in order to maintain the set temperature Not all heat pumps are variable-speed like you describe. My own home, built in 2000, has a single-speed heat pump that kicks on 100% or off, like a regular old AC unit.

Right, what I'm trying to say is that it is normal for it to be on 100% of the time when it is cold out. If you are used to gas heat which can turn on for 15 minutes, overshoot the set point, and then be off for the next 45 minutes, a heat pump will seem strange.

Mine is a variable speed unit, but that's not the function that I'm talking about.

Re: How a heat pump works

#67

Post by flakeoil »

notdarkyet wrote: post #34
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…

I see this as well and it looks to be multiple people buying in to the campaign, especially here on HN. Having lived in a new, high end apartment that had a heat pump for both heating and cooling for 3 years, I am very unimpressed with the tech. Running nonstop, couldn't heat/cool above/below a certain threshold. Electric bill very high. Clogged and broke a lot. If the general radiant heat and cooling from being in l…

Also remember that air-to-air heat pumps are overall less efficient and powerful than air-to-water or geothermal-to-water type heat pumps.

Firstly the later typically have a higher power rating.

Secondly, if you can lead water around the house and heat via radiators or floor heating you get a much better efficiency.

Re: How a heat pump works

#68

Post by SigmundA »

nashashmi wrote: post #16
nicoburns wrote: post #9

Earlier quoted context omitted.

> Is there a global push to get everyone to switch to heat pumps. I mean, yes. They're much more energy efficient than the alternatives and will play a key part of removing our dependence on fossil fuels. > I understand that its for climate benefits but it feels very coordinated. That seems like a good thing?

They are not more energy efficient than burning gas. Edit: since i am getting downvoted to oblivion, let me fight back here. I genuinely wished heat pumps would be more efficient and in theory they can be. I would love to not generate heat and just use the outside heat energy and compress it down into a smaller location. But compressing and decompressing is not an energy efficient task. It takes a lot of work. Mechan…

They can be, natural gas is about 1000 BTU per cubic foot.

An expensive high efficiency gas furnace might be 95% efficient (most normal furnaces are in the 80's)

1000 x 0.95 = 950 BTU/cuft

A high efficiency natural gas power plant is 60% efficient and a modern high efficiency low temp heat pump can have a COP up to around 2.7 at 17F

1000 x 0.6 x 2.7 = 1620 BTU/cuft

A 40% power pant is still more efficient than a 95% furnace with a 2.7 COP heat pump.

There is obviously more to this, there are some grid losses to account for but has to be compared to piping losses, there is also cost factors and also how much renewable is mixed into your grid supply, but generally once that heat pump is above around 2.5 COP it starts to make sense, this is a no brainer in milder climates which is why I have a heat pump and no gas furnace here in FL even though I have gas to the house for other uses.

Re: How a heat pump works

#70

Post by PragmaticPulp »

wongarsu wrote: post #27
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…

For a long time the main problem of heat pumps was that while they are more efficient, a kilowatthour of gas or oil is much cheaper than a kilowatthour of electricity. But in the last two years natural gas prizes have gone crazy, removing that price disadvantage. Of course heat pumps emitting no particulates and being able to run on renewables are also good reasons, especially as the health impact of living in cities…

Heat pump technology has also improved significantly. You can now buy heat pumps that remain efficient down to very low temperatures, which makes them appropriate for a larger range of climates now.

Many models are in very high demand. Some of the units I looked at recently were back ordered so far that I was told to pick something else if I expected to have it within the year.

The demand is very high because the technology is good. It’s not a campaign or conspiracy.

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