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How a heat pump works

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Re: How a heat pump works

#201

Post by steve76 »

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%…

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Re: How a heat pump works

#202

Post by Calvin02 »

spikej wrote: post #199

Genuine question that I haven't been able to find a clear answer for: are heat pumps now different from air conditioners two to three decades ago? (other than the fact that they heat and cool) Memory is fuzzy but I remember when I was a little kid and even captain planet cartoon showed air conditioners being bad for the environment... Or is it that heat pumps are better than the fossil fuel counterparts and so if you…

It is the latter.

Heat pumps are much better for the environment compared to the other sources of heating. Depending on where you live, you still need to heat your place and if so, heat pumps are better than other traditional methods like natural gas, wood, oil, or electricity.

Similar to air conditioning, if you want to minimize your impact on the climate, you could set your temperature lower in the winter and put on a few more layers and/or set the temperature higher in the summer to minimize your usage of heat pump/air conditioner. This puts less pressure on the grid and demand for electricity generation.

Re: How a heat pump works

#203

Post by bagels »

spikej wrote: post #199

Genuine question that I haven't been able to find a clear answer for: are heat pumps now different from air conditioners two to three decades ago? (other than the fact that they heat and cool) Memory is fuzzy but I remember when I was a little kid and even captain planet cartoon showed air conditioners being bad for the environment... Or is it that heat pumps are better than the fossil fuel counterparts and so if you…

Captain Planet is not a reliable source of information. Air conditioners use electricity, the generation of which can cause fossil fuels, but also can come from other sources.

Re: How a heat pump works

#204

Post by mikeyouse »

kortilla wrote: post #193
mikeyouse wrote: post #178

Earlier quoted context omitted.

Apologies that link was broken -- but that was a "Commercial Style" stove for a home, not actually a commercial appliance. In any case vents are a really bad solution.. but they're inefficient at removing fumes, are usually undersized and too far from the cooking surface, and most people don't use them because they're obnoxiously noisy when running at the proper speed. A friend of mine just remodeled their kitchen --…

“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!"

Re: How a heat pump works

#205

Post by ctroein89 »

timerol wrote: post #145
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...

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 option.

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.

Re: How a heat pump works

#206

Post by ccooffee »

spikej wrote: post #199

Genuine question that I haven't been able to find a clear answer for: are heat pumps now different from air conditioners two to three decades ago? (other than the fact that they heat and cool) Memory is fuzzy but I remember when I was a little kid and even captain planet cartoon showed air conditioners being bad for the environment... Or is it that heat pumps are better than the fossil fuel counterparts and so if you…

> even captain planet cartoon showed air conditioners being bad for the environment

That seems like it was a useful simplification for a children's cartoon, but things aren't that black-and-white.

1. Without air conditioning (or some other method of cooling and humidity control), almost all high-occupancy buildings would reduce their effectiveness as a work-place or living-place. OSHA has guidelines about office temperature (68-76, iirc), humidity, and overall air quality (e.g. pm2.5 levels).

2. The 1980s-era backlash against air conditioning was likely inspired by then-new knowledge about atmospheric ozone depletion. It was known that CFCs and bromine-containing compounds contribute to ozone depletion. It just so happens that CFC were common refrigerants (and aerosolizing agents). Refrigerant leaks from an air conditioner in those times released nasty stuff. CFCs are very rare (and restricted) in modern air conditioner / hvac systems. We instead use other chemicals which are not ozone depleters. (Though I believe that the theoretical performance of modern refrigerants is often not-as-good as the old CFCs.)

3. Running the air conditioner in a single family home is not terribly efficient, as (in most single family homes) most of the home is just empty space. Cooling bodies directly (e.g. cooling blankets, misting fans, etc) is more energy-efficient in these situations. Perhaps the more nuanced advice would be to use air conditioning to make the space "tolerable" but use direct cooling to make a space "comfortable". (This advice also applies to heating a space. I keep my thermostat between 60 and 65 and use blankets, small electrical resistance heaters, and drinking hot water as ways to temperature-regulate.)

Re: How a heat pump works

#207

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…

Just to counter your edit:

>But compressing and decompressing is not an energy efficient task. It takes a lot of work. Mechanical inefficiencies are a huge energy consumption. Gas is simply burning fuel. Yes, we should save gas for rainy days. But I hate to say that it is more efficient and cheap. There is no comparison.

You are very mistaken, the energy required to compress refrigerant is less than the energy captured and delivered if COP > 1, which is the point of a heat pump. At COP 1 it is basically heat of compression and equal to a resistive heater at COP greater than 2 the heat pump captured more heat from the environment than used to compress the refrigerant.

I am not sure if you are arguing in good faith, if so here are some of the simplest resources I can find to explain how a heat pump can exceed a furnace in efficiency even when taking power plant and transmission losses into account, with easy to understand graphics:

https://greenbusinesswatch.co.uk/cop-vs-spf

https://energyeducation.ca/encyclopedia/Coefficient_of_perfo...

http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/heatpump.h...

This should really be taught and drilled in lower education, the difference between heat and temperature and relationship to power, how heat engines work, etc. This stuff basically makes modern society possible and we will never progress in decoupling our power sources from use of the power which is what electrification allows which allows us to transition away from throwing carbon up in the air for energy.

Re: How a heat pump works

#208

Post by danans »

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…

> worth looking at who the winners are and what the trade offs are.

The winners are consumers, the effort to reduce GHG and particulate emissions, and the drive toward energy independence (whether at the national, local, or hyper-local level).

The losers are fossil fuel extraction industries, because due to the high COP of heat pumps, far more heat is delivered per unit of energy consumed, even if that energy ultimately comes from burning natural gas at a power station. Also, the source of the energy itself gets disintermediated, since electricity can come from multiple sources, including renewables.

The tradeoffs are (for now): Higher upfront installation cost (tempered by the IRA, and potentially lower operating costs), availability of the equipment (supply chain stuff), and long delays in installation due to lack of qualified installers (and resulting high costs).

Re: How a heat pump works

#209

Post by quickthrowman »

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…

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

Re: How a heat pump works

#210

Post by p1mrx »

triceratops wrote: post #181
thekingshorses wrote: post #171

Earlier quoted context omitted.

If there is a power outage, you can't run your natural gas heater either. It needs fan to run.

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.
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