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How a heat pump works

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Re: How a heat pump works

#121

Post by oh_sigh »

oceanplexian wrote: post #85
wongarsu wrote: post #27

Earlier quoted context omitted.

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…

An overlooked benefit is that they actually improve comfort over a boiler in a dry climate, so if you live somewhere with low humidity they help keep the air less dry. They also give you heating and cooling.. for places that don’t have Air Conditioning it’s a worthwhile upgrade.

Sure, but you can get a whole home.humidifier for like $300 to mitigate that issue.

Re: How a heat pump works

#122

Post by nashashmi »

SigmundA wrote: post #68
nashashmi wrote: post #16

Earlier quoted context omitted.

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%…

I am in NY. And I think for Florida, a heat pump makes because of a hybrid AC model. Even if electricity is more expensive, the equipment and energy cost of a separate unit is not worth spending.

In extreme climates, gas burning is cheaper. And quite clean. There are some objections because of delivery leaks, but that is a separate concern.

Re: How a heat pump works

#123

Post by boringg »

achenatx wrote: post #96
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…

my friend is building his house and is putting in 4 heat pumps (big house). The problem is we just lost power for 4 days and 2 years ago we lost power for 5 days. He is discovering that electric heat uses massive amounts of electricity and there is no way to get a residential generator big enough to power them all. He might not even be able to power one (they can use in excess of 20kw). I would never get electrical w…

So this is one of my big concerns - I live in a cold weather country currently. We have power outages once every couple of years. If I don't have back up power my pipes freeze and then i'm out probably > $50k.

I was thinking the solution for me is to put in a heat pump and then run a backup gas generator. But that solution feels like a significant amount of overbuild. I have 3 minisplits already but they aren't valuable in the winter -- where you install your AC units isn't where you would install your heating units .. I.e. the top of my house for AC, the bottom of the house for heat.

Having multiple energy sources to defray risk is helpful.

Re: How a heat pump works

#124

Post by sbradford26 »

wongarsu wrote: post #97
megaman821 wrote: post #91

Earlier quoted context omitted.

I assume in home that don't have ACs, that they also don't have ducts. Do these ductless homes filter their air, control home humidity, or bring in fresh air from outside?

"Ductless homes" usually circulate hot water through radiators. If you switch to a heat pump, nothing's stopping you from circulating cold water in the summer, though obviously there is a limit on the temperature delta (you can heat water much more than you can cool it). Bringing in fresh air is a manual process (open the windows), and filtering air or controling humidity is then left to seperate appliances, if done…

There are many reasons why you can't just circulate cold water though a radiator to cool. As another commenter stated you will get large amounts of condensation. But the other reason is that you do not get nearly as effective of convection currents with cool versus heating. Your radiators utilize convection currents to circulate the warm air around the room. Running chilled water though the a radiator would be like having an ice cube in the corner of the room. It isn't going to cool the whole room down and will get water everywhere.

Re: How a heat pump works

#125

Post by nashashmi »

snuxoll wrote: post #104
SigmundA wrote: post #68

Earlier quoted context omitted.

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%…

> 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. They're a no-brainer in every climate. Newer heat pumps can handle fairly cold temperatures (-13°F) pretty easily, there may be a loss in efficiency but in the majority of the world it doesn't stay that cold. A few days of lower than normal efficiency, and at wors…

Ok! I am genuinely interested in how heat pumps are more efficient. My online search led me to calling heat pumps more efficient when compared to electric heaters. And better in other ways compared to gas burners. But lord's sake, they were all upselling marketing sites for heat pumps.

I am looking for genuine research, and not from paid mouth pieces.

Majority of the comments here seem like agents of heat pump industry. And HN rules forbid me from calling them that.

Re: How a heat pump works

#126

Post by mytailorisrich »

Thlom wrote: post #95
mytailorisrich wrote: post #77

Earlier quoted context omitted.

It's not directly related to the recent spike in prices, especially considering that a heat pump installation is very expensive in itself and potentially disruptive. Rather, it's a combination wanting to get to net zero, so no emissions, with the big problem of generating enough green electricity. A heat pump system has no emissions and consumes much less electricity than an electric boiler/electric heater.

I replaced my old air-to-air heat pump with a new one last year. Cost me in total around $3000-$4000. Might have been a bit more expensive if it was a completely new install depending on how it would be installed, but not too much more expensive. Might be more expensive in countries where you are using gas boilers as it sounds like your heating setup is much more complex than where I live.

Here in the UK, I think the cost of installing a new heat pump, bearing in mind that it's an installation from scratch, starts at about £10k ($12k as today's rate) to several tens of thousands. A ground source heat pump (which seem to be the ones pushed by the gov?) is probably £15k to £30k if you can install one at all. Replacing an existing gas boiler, which is what most people have, is probably around £2k or even less in simple cases. I had mine replaced 2 years ago with the new one installed on a different floor so a fair amount of plumbing was required, and it 'only' cost me £3k.

There are government subsidies but it's still much more expensive in the end. I think they are simply too expensive and impractical to install for most people.

Re: How a heat pump works

#127

Post by Nihilartikel »

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…

The new order world government will have to pry my wood burning lightbulbs from my cold dead guns!

Re: How a heat pump works

#128

Post by thehappypm »

nashashmi wrote: post #111
gabrielhidasy wrote: post #65

Earlier quoted context omitted.

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.

400% efficiency? Is that even possible? (Did AI write this?)

Yes, you might want to do some research on it.

The core idea is that you aren’t using 1 unit of electrical energy to create 1 new unit of heat energy. You are using 1 unit of electrical energy to capture several units of pre-existing heat energy from the environment and pump it indoors.

Re: How a heat pump works

#129

Post by fullstop »

slfnflctd wrote: post #79
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.

What's the payback time on something like that for a modest home in a place which can get significantly under 20 degrees (F) or over 95 degrees for weeks or longer? How effective is it at those extreme temperatures when it matters the most, and how does this affect maintenance costs? Additionally, there are multiple types of restrictions on where geothermal pumps can be installed, and navigating this can add to costs…

Obviously nobody can answer the long term cost differences between gas and heat pumps, since the cost of natural gas and electricity can change drastically over the lifetime of the unit.

GP's comment was about the tech, though, and not the cost of said tech.

It's absolutely not a perfect solution for all heating needs across the globe, the the technology is far better than GP is suggesting.

Re: How a heat pump works

#130

Post by sbradford26 »

nashashmi wrote: post #111
gabrielhidasy wrote: post #65

Earlier quoted context omitted.

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.

400% efficiency? Is that even possible? (Did AI write this?)

So the term efficiency with heat pumps typically refers to COP Coefficient of Performance. It a measure of how many watts of heat you are able to pump per given watt of electricity used. So 400% would be a COP of 4.0 which is definitely possible with air source heat pumps in milder weather and ground source heat pumps in pretty much any weather.
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