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How a heat pump works

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Re: How a heat pump works

#141

Post by sparsely »

endisneigh wrote: post #105
bilsbie wrote: post #101

Earlier quoted context omitted.

I’m confused what you’re asking for (and why) but it sounds interesting.

A portable machine to provide heat and cooling via heat pump technology. For cooling this exists in many forms: there are the window air conditioners, and "portable" window air conditioners which have a duct that connects to the window. The problem with the latter is that they're loud and the ducts result in a lot of heat loss. For heating there are some portable air conditioners that use a heat pump but they're subj…

I believe you are describing something like this: https://mrcool.com/u-shaped-window-a-c/ Never used one myself but they are meant to be much better than the ones with ducts - you don't lose so much efficiency from the ducts or from badly patched up window openings.

Re: How a heat pump works

#142

Post by snuxoll »

sbradford26 wrote: post #135
snuxoll wrote: post #104

Earlier quoted context omitted.

> 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…

So heat pumps do lose efficiency at lower temperature such as -13F but the much bigger issues is loss of capacity. If you look at the curve of available heating capacity of a heat pump versus the heating needs for your house that tend to be a bit of a mirror image. When it is warmer out your house needs less heat but heat pumps have the highest capacity they will have. As temps drop the house will require more heat w…

> Which might require multiple heat pumps and separating existing duct work. But definitely new construction should start designing around these constraints now.

Ductless mini-splits remain an option as well. I'd actually like to see somebody make some ground-source exchanger that ductless heads could connect to, because they're much cheaper to install than a multi-zone ducted system.

Re: How a heat pump works

#143

Post by elil17 »

boringg wrote: post #134
elil17 wrote: post #117

Earlier quoted context omitted.

Well of course it is being pushed, though I would not necessarily call it coordinated. Companies that sell heat pumps are advertising hard. It's an easy sell for them with rising gas prices. The US government is "pushing them" by offering tax credits for heat pump systems. This is part of a plan to reduce pollution, improve energy independence/energy security, and save citizens money on their heating bills. No secret…

I think this is probably the right answer. It keeps popping up everywhere. I'm always a skeptic on when something gets super hyped. In this case it's more use-case specific that makes me skeptical - majority of people its 100% fit.

I also tend to be skeptical when I see something hyped, but I work in this space and I can say that this tech is really the best option for most residential applications.

It's old tech, it's been around since the 1800s. The only thing that has changed is that heat pumps have gotten cheap and energy has gotten expensive.

There are applications where heat pumps cannot replace boilers - in industrial processes where high temperatures are required or tremendous capacity is needed intermittently.

However, unless your temperatures are routinely below about -20 F, a heat pump is the best choice (and even if temperatures occasionally drop below that, heat pumps are still an excellent choice because those extreme temperatures might only last for a handful of hours out of the year, during which insulation or a cheap electrical resistance heater can keep you warm).

Re: How a heat pump works

#144

Post by almuhalil »

endisneigh wrote: post #105
bilsbie wrote: post #101

Earlier quoted context omitted.

I’m confused what you’re asking for (and why) but it sounds interesting.

A portable machine to provide heat and cooling via heat pump technology. For cooling this exists in many forms: there are the window air conditioners, and "portable" window air conditioners which have a duct that connects to the window. The problem with the latter is that they're loud and the ducts result in a lot of heat loss. For heating there are some portable air conditioners that use a heat pump but they're subj…

There is a portable mini-split that recently came onto the market, and its form factor is similar to that of a window AC: https://www.gradientcomfort.com/

The only problems I can see are:

-Size/Price ratio: The tonnage (9,000 BTU) is relatively low for its price--it can only condition a ~375 sq foot space. Though the lack of install costs probably makes up for this unless you're doing a DIY job with a Mr. Cool Ductless HP.

-Incentives: Utilities may not want to spend energy efficiency incentive dollars on these, since someone could easily move and take the heat pump outside of the utility territory; which is not a problem with permanent HVAC installations. Might be covered by the IRA's rebates for Heat Pumps though.

Re: How a heat pump works

#145

Post by timerol »

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.

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...

Re: How a heat pump works

#146

Post by SigmundA »

nashashmi wrote: post #125
snuxoll wrote: post #104

Earlier quoted context omitted.

> 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 indust…

Just do the math, all you need to know is furnace efficiency and COP of the heat pump along with the efficiency of your local power plant. I did that in my post, its not super complicated.

Gas is burned creating a certain amount of heat, in a furnace some is lost to exhaust the rest goes into your house. That is the furnace efficiency.

When gas is burned at a power plant the same number of BTU is released, but it is used instead in a heat engine to create mechanical power which is then turned into electrical power, the rest is lost to exhaust, this is the power plant efficiency.

Heat pumps are over 100% efficient because they capture heat from the environment around your house which is warmed by the sun. So even though more energy is lost in creating electricity than burning directly in your house, this is more than made up for by using the ambient heat around your house, it is essentially solar assisted (in the case of air source).

Re: How a heat pump works

#147

Post by amiga386 »

gabrielhidasy wrote: post #65
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 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.

Sorry for nit-picking, but gas power plants burn 50-60% efficiency when waste heat is reused, compared to 30-40% efficiency with a single cycle.

https://en.wikipedia.org/wiki/Combined_cycle_power_plant

> (CCGT) plant[s] achieve a best-of-class [...] thermal efficiency of around 64% in base-load operation. In contrast, a single cycle steam power plant is limited to efficiencies from 35 to 42%

Re: How a heat pump works

#148

Post by billjings »

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…

Here's a couple of reasons:

1. The American market has a lot of incorrect perceptions of heat pumps. Debunking these makes for great viral content! 2. The IRA introduced big incentives for various electrification expenses.

The incentives are the big thing, but the public interest/controversy part is why some enhancements like heat pumps and kitchen electrification ("don't take away my gas stove!") are going more viral than, say, electric vehicles (technology connections guy has some good EV content, but it's not doing quite the same numbers)

Re: How a heat pump works

#149

Post by sbradford26 »

snuxoll wrote: post #142
sbradford26 wrote: post #135

Earlier quoted context omitted.

So heat pumps do lose efficiency at lower temperature such as -13F but the much bigger issues is loss of capacity. If you look at the curve of available heating capacity of a heat pump versus the heating needs for your house that tend to be a bit of a mirror image. When it is warmer out your house needs less heat but heat pumps have the highest capacity they will have. As temps drop the house will require more heat w…

> Which might require multiple heat pumps and separating existing duct work. But definitely new construction should start designing around these constraints now. Ductless mini-splits remain an option as well. I'd actually like to see somebody make some ground-source exchanger that ductless heads could connect to, because they're much cheaper to install than a multi-zone ducted system.

They make systems like that but they tend to be more commercial systems. You could get a ground to water heat pump then run chilled/heated water to the mini split heads depending on what they are calling for but even that is pushing into commercial territory. And sadly with commercial HVAC comes significantly higher prices.

Re: How a heat pump works

#150

Post by SigmundA »

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?)

https://en.wikipedia.org/wiki/Coefficient_of_performance
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