Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

How a heat pump works

hvac-learning.com

Post reply on HN
Print view View original

211–220 of 332 posts

Re: How a heat pump works

#211

Post by bobthepanda »

mytailorisrich wrote: post #77
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…

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.

They are also kind of a 2 in 1 appliance, in that they can run in reverse and cool your home, and are much more efficient at that than traditional ACs.

In the US where AC is common, summer is generally peak electricity usage. I suspect this will become true in Europe as well with the heatwaves becoming a regular occurrence.

Re: How a heat pump works

#212

Post by triceratops »

p1mrx wrote: post #210
triceratops wrote: post #181

Earlier quoted context omitted.

But you can run a furnace fan off a diesel generator.

Why diesel? If you need natural gas to run the furnace, it might as well run the generator too.

Maybe "fossil fuel powered generator" would've captured better what I meant.

Re: How a heat pump works

#213

Post by [deleted] »

oh_sigh wrote: post #121
oceanplexian wrote: post #85

Earlier quoted context omitted.

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.

[deleted]

Re: How a heat pump works

#214

Post by vikingerik »

Nihilartikel wrote: post #132
nashashmi wrote: post #111

Earlier quoted context omitted.

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

If I can spend 1 joule to transfer two joules of enthalpy from outside to inside, then that is 200% efficiency. Burning 1 joule of gas would give you 1 joule of heat in a perfect world. That is what a non pump does.

Where exactly does that first spent joule go, thermodynamically speaking? Is it also converted to heat within the electromechanicals of the heat pump?

Re: How a heat pump works

#215

Post by scythe »

endisneigh wrote: post #90

I wish, wish wish there was a portable mini split (not a portable air conditioner). The closest thing is this: https://rollibot.com/product/mini-split-ac-room-air-conditio... but it sucks. I don't understand why these things have to be permanent fixtures of your house, necessarily.

The issue is that cold should be supplied near the ceiling, while heat should be supplied near the floor. So this unit would need two separate terminals or suffer inadequate performance in one of the modes.

Re: How a heat pump works

#216

Post by SigmundA »

vikingerik wrote: post #214
Nihilartikel wrote: post #132

Earlier quoted context omitted.

If I can spend 1 joule to transfer two joules of enthalpy from outside to inside, then that is 200% efficiency. Burning 1 joule of gas would give you 1 joule of heat in a perfect world. That is what a non pump does.

Where exactly does that first spent joule go, thermodynamically speaking? Is it also converted to heat within the electromechanicals of the heat pump?

Yes so not only are you capturing heat from the environment you are turning electricity into heat in the compressor, both are delivered as heat to the interior. This is an advantage compared to cooling where you must reject both the interior heat and the heat of compression.

Re: How a heat pump works

#217

Post by kenmacd »

pkulak wrote: post #136
yreg wrote: post #6

Technology Connections has a good video on heat pumps. (Actually several of them, I link the newest one.) https://www.youtube.com/watch?v=MFEHFsO-XSI

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

I like his videos, but I don't trust his numbers in this one. He shows a COP of ~1 when it's 10 degrees out. These are the easiest possible conditions for the HP, and where all the specs show the highest COP. His graph showing the HP is running equal to a baseboard heater seems very suspect.

Re: How a heat pump works

#218

Post by scythe »

ctroein89 wrote: post #205
timerol wrote: post #145

Earlier quoted context omitted.

NYCHA is currently running a contest to develop a heat pump window unit. All of the proposed units are expensive to get those contest dollars, but should come down in price after. https://www.gradientcomfort.com/pages/products-air-condition... https://www.achrnews.com/articles/147122-midea-heat-pumps-to...

I have two heat pump window air conditioners installed in my apartment, with cooling, heating and resistance electrical heating: https://www.frigidaire.com/Home-Comfort/Air-Conditioning/Win... . The problem is that the tech is so poorly advertised, that I had to double-check the specs on manufacturer's website that this model was, in fact, a heat pump. Most people don't know that heat pump window units already are an…

>I'd love for NYC to mandate that ACs must function as heat pumps: the additional parts are cheap, and as America's largest market for window AC units, the NYC market would force competition for much cheaper heat pump window units.

This isn't great if you want a building with hydronic heating and forced-air cooling, which is really just the ideal form of both technologies — hydronic cooling creates condensation, while forced-air heating smells bad and leaves you with cold feet.

Also, I found that Home Depot's website tends to be pretty clear about which window units are also heat pumps.

Re: How a heat pump works

#219

Post by brewdad »

quickthrowman wrote: post #209
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…

NG (in the US) is now about 70-80% cheaper than it was at the recent highs.

And my local utilities just got approved for massive rate increases locking in those higher prices. Of course, I probably wasn't paying the full costs this past year.

Re: How a heat pump works

#220

Post by jamiek88 »

nashashmi wrote: post #13
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…

Heat pumps are the opposite of AC. AC industry is behind this for sure. It is like a paid PR campaign. It is not more economical then gas. So now gas is going to be punished for factors X,Y,Z. It is coordinated. I wish there is more investigative research into who and why they are doing this.

In this thread you’ve gone form ‘compressors don’t work like that’ to ‘this is all a conspiracy by big A/C’.

You are not engaging with any of the helpful, generous replies, in fact going as far as to say that you wish you could call it ‘coordinated’.

Why are you even here if you think we are all lying shill for big air compressor?

Post reply on HN