3 ms·

Heat pumps have COP of 2-4, so in either heating or cooling mode, they generate more heating/cooling than electricity used. But the reason cooling is cheaper i

by coryrc 4y ago

Heat pumps have COP of 2-4, so in either heating or cooling mode, they generate more heating/cooling than electricity used. But the reason cooling is cheaper is the temperature differential. AZ might get to, say, 110°F peak (and far cooler at night), for a temp delta of 35°F while the Midwest will stay below 20°F for months, and even colder at night, for a temp differential no better than 50°F during the day and 60°F at night.

Scoundreller 4y ago
And heat pump efficiency takes a dump when it has to go through defrost cycles in heating mode at near/below freezing temps. In cooling mode they provide a source of fresh-distilled water! It always bothered me when air conditioners just dump that water down the sanitary drain instead of pumping it in a garden or misting it on the outside coils.
- coryrc 4y ago
  Yeah, air source has problems at cold temperatures, especially if they cheap out on ice detection. Fresh is not the word I would use for condensate. Try drinking some of you disagree :). It's corrosive for metal,{EDIT: maybe I just have that confused, see replies} which is why it usually doesn't find a purpose, but you could run it to plants. I have a window A/C which uses it for cooling the outside coils though.
  - Scoundreller 4y ago
    Still wouldn't drink it unless I'm desperate, but I don't see why it would be corrosive. Maybe slightly basic from being in contact with metals, but it couldn't be much unless your coils and fins are disappearing before your eyes. Legionella is a concern though. https://www.environmentalleader.com/2013/01/air-conditioning-condensate-recovery/ https://www.environmentalleader.com/2013/01/air-conditioning...
    - coryrc 4y ago
      I think it's the lack of minerals? But it obviously forms on metal coils to begin with. Maybe I'm confusing it with condensate from condensing natural gas burners.
clairity 4y ago
> "...they generate more heating/cooling than electricity used." that's thermodynamically impossible. @dktoao, being a mechanical engineer, surely understands this, and made a statement that is different, and more plausible. COP is a ratio of change in energy (e.g., temperature) produced against a common benchmark (running electricity through a resistive element, for example). that's how it can be greater than 100%. absolute efficiency (what @dktoao offered) compares against a 100% conversion of energy from one form (or place) to another. in this case, you cannot beat 100% (or generally get super close) due to the 2nd law of thermo.
- coryrc 4y ago
  Basically no common A/C is 30% efficient in any sense of the word. There's a scenario where you can argue it can get as low as 50%, but no common A/C I have ever heard of is using moving less than 2x heat power as electricity power used. 30% is wrong no matter how you cut it. And, "efficiency" doesn't matter. COP does. COP is what is reflected on your electrical bills.
  - clairity 4y ago
    it's basic thermodynamics. you mixed the two, as i explained previously, and now you're leaning into the misconception, rather than acknowledging the difference.
    - coryrc 4y ago
      In no way is anything you said in either post of use to anyone. If I am in my house, use 1000 W of electricity, get 3000 W of heating, that is what is important. No shit the extra heat comes from the environment. It doesn't matter unless you live within a house completely located inside an artificial climate-controlled area, which applies to... none. No houses.

by coryrc 4y ago

Scoundreller 4y ago

And heat pump efficiency takes a dump when it has to go through defrost cycles in heating mode at near/below freezing temps. In cooling mode they provide a source of fresh-distilled water! It always bothered me when air conditioners just dump that water down the sanitary drain instead of pumping it in a garden or misting it on the outside coils.

coryrc 4y ago
Yeah, air source has problems at cold temperatures, especially if they cheap out on ice detection. Fresh is not the word I would use for condensate. Try drinking some of you disagree :). It's corrosive for metal,{EDIT: maybe I just have that confused, see replies} which is why it usually doesn't find a purpose, but you could run it to plants. I have a window A/C which uses it for cooling the outside coils though.
- Scoundreller 4y ago
  Still wouldn't drink it unless I'm desperate, but I don't see why it would be corrosive. Maybe slightly basic from being in contact with metals, but it couldn't be much unless your coils and fins are disappearing before your eyes. Legionella is a concern though. https://www.environmentalleader.com/2013/01/air-conditioning-condensate-recovery/ https://www.environmentalleader.com/2013/01/air-conditioning...
  - coryrc 4y ago
    I think it's the lack of minerals? But it obviously forms on metal coils to begin with. Maybe I'm confusing it with condensate from condensing natural gas burners.

clairity 4y ago

> "...they generate more heating/cooling than electricity used." that's thermodynamically impossible. @dktoao, being a mechanical engineer, surely understands this, and made a statement that is different, and more plausible. COP is a ratio of change in energy (e.g., temperature) produced against a common benchmark (running electricity through a resistive element, for example). that's how it can be greater than 100%. absolute efficiency (what @dktoao offered) compares against a 100% conversion of energy from one form (or place) to another. in this case, you cannot beat 100% (or generally get super close) due to the 2nd law of thermo.

coryrc 4y ago
Basically no common A/C is 30% efficient in any sense of the word. There's a scenario where you can argue it can get as low as 50%, but no common A/C I have ever heard of is using moving less than 2x heat power as electricity power used. 30% is wrong no matter how you cut it. And, "efficiency" doesn't matter. COP does. COP is what is reflected on your electrical bills.
- clairity 4y ago
  it's basic thermodynamics. you mixed the two, as i explained previously, and now you're leaning into the misconception, rather than acknowledging the difference.
  - coryrc 4y ago
    In no way is anything you said in either post of use to anyone. If I am in my house, use 1000 W of electricity, get 3000 W of heating, that is what is important. No shit the extra heat comes from the environment. It doesn't matter unless you live within a house completely located inside an artificial climate-controlled area, which applies to... none. No houses.