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Harnessing America's heat pump moment

heatpumped.org

61–70 of 571 posts

Re: Harnessing America's heat pump moment

#61

Earlier quoted context omitted.

The physics of heat pumps disagrees with you. The freezing point of water has no bearing on at what point they become less effective.

Heat pumps lose efficiency as it gets colder. There are no laws of physics which contradict this.

The relevant laws of physics operate in Kelvin. 60°F is 288 K. -20°F is 244 K. These are not that far apart.

Re: Harnessing America's heat pump moment

#62
post #33

People are reluctant to install them because they don't work as well as the good old boilers we'd be replacing. I'm not saying they can't, and I'm not saying that there are zero models out there that work. But in practice, a lot of us that have interacted with heat pumps have the specific experience that they get anemic as the temperature goes down and eventually become unable to do much of anything. I live in the mi…

The radiators might make you feel warmer despite not actually making the air in the room warmer: the black body radiation from the big warm radiators affects your perception of warmth in a not insignificant way.

Re: Harnessing America's heat pump moment

#63
post #33

People are reluctant to install them because they don't work as well as the good old boilers we'd be replacing. I'm not saying they can't, and I'm not saying that there are zero models out there that work. But in practice, a lot of us that have interacted with heat pumps have the specific experience that they get anemic as the temperature goes down and eventually become unable to do much of anything. I live in the mi…

How is the insulation in the house? Poor insulation and an undersized system will be a bad experience regardless of the heat source.

It wasn't a bad experience before, but now it is, because of: new heat pump

Re: Harnessing America's heat pump moment

#64
Recently went with heat pump water heater and cloths dryer, very significant energy savings and they both work great using around 1/3 the energy.

Most of my energy is for HVAC cooling in the south and that is already a heat pump. The house is well insulated and also have solar so along with the water heater and dryer I am around net zero in mid summer and and now that temperature is more mild I am producing much more than using even with one EV as well.

It really nice to have an all electric house along with at least one car and a large solar backup system I am pretty self contained and don't really have to change anything if grid goes down.

Re: Harnessing America's heat pump moment

#65

Earlier quoted context omitted.

How is the insulation in the house? Poor insulation and an undersized system will be a bad experience regardless of the heat source.

It wasn't a bad experience before, but now it is, because of: new heat pump

Well what capacity does each system have?

That they came back and added resistive heating suggests your contractor may not have been too worried about sizing the system correctly in the first place.

Re: Harnessing America's heat pump moment

#66
post #33

People are reluctant to install them because they don't work as well as the good old boilers we'd be replacing. I'm not saying they can't, and I'm not saying that there are zero models out there that work. But in practice, a lot of us that have interacted with heat pumps have the specific experience that they get anemic as the temperature goes down and eventually become unable to do much of anything. I live in the mi…

Resistive heat strips are what all electric furnaces use. It's just a bunch of coils of nichrome heating wire. The efficiency of a resistive heater is basically 100%. One Watt of electricity in gives you one watt of heat out.

The mistake people make is assuming a heat pump can do everything by itself anywhere in any climate. If you have cold winters, you need a dedicated furnace to supplement the heat pump.

I say supplement because while an electric furnace is near 100% efficient at turning electricity into heat, a heat pump can be far more than 100% efficient. And that's the crucial detail: a heat pump can give you more heat per Watt than a resistive heater when outside temperatures are warm enough.

Re: Harnessing America's heat pump moment

#67
post #33

People are reluctant to install them because they don't work as well as the good old boilers we'd be replacing. I'm not saying they can't, and I'm not saying that there are zero models out there that work. But in practice, a lot of us that have interacted with heat pumps have the specific experience that they get anemic as the temperature goes down and eventually become unable to do much of anything. I live in the mi…

The strength of your heat pump shouldn't be outside surface temperature, but underground aquifer temperature. Those two temperatures are related but not as directly as they seem. A good aquifer in certain cavernous regions of the US might stay about 55 degF year round, regardless of outside surface temperature. 55 degF is still below what a lot of people want their home to be year round so a heat pump still has to su…

You're talking about geothermal heat pumps which are far less common than air-to-air heat pumps because they are far more expensive.

These are entirely disjoint concepts.

Re: Harnessing America's heat pump moment

#69
post #25

Earlier quoted context omitted.

A possible challenge, yes, but there exist 1500w, standard outlet hpwh, and it's a lot less common to not have any power near a water heater.

A 1500W electric water heater would be painful to use in a home. A typical 30-60 gallon EWH is 6kW. And for the record, every single natural gas water heater is connected to 120V power for the ignition circuit.

a 1500W heat pump water heater with a COP around 3 will put 5500 watts of heat into the water.

My Rheem hybrid 220v heat pump water heater only has a 500w compressor but puts 1500-2000 watts of heat into the water pulling it from the hot garage.

I have the choice to run it in high demand mode which will run both the heat pump and electric 4500w element for around 6kw of heat into the water if I need fast recovery.

Re: Harnessing America's heat pump moment

#70

Is Heat Pump the same as what Australian's would call a Split System?

Split system is a common term that covers both heat pumps and traditional AC systems. It has to do with the physical setup, not the theory of operation.

A heat pump specifically is an AC system that can run in reverse: moving heat from outside to inside.

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