7 ms·

Heat pumps are approximately three times as efficient as electric heating.

pas 6y ago
That needs good insulation first, or am I missing something? Usually space heaters are warmer, but less efficient. Heat pumps are great if you have time to warm up the space but if it's insulated like an open field, you'll be always cold.
- _Microft 6y ago
  Why wouldn't one insulate the space? Heating is no end in itself.
- zejn 6y ago
  Heat pump is essentially a "reverse mount of a refrigerator", putting heat in and throwing cold out. In the worst case, the pump will degrade into a heating element, only outputting heat from electricity (which is what a regular electric heater does). Insulation is not a requirement, but will lower your energy needs to keep a steady temperature.
shawnz 6y ago
They also don't provide very much heat output when it's cold outside
- foepys 6y ago
  It needs to be really cold. Like -15°C and some go as low as -40°C. They degrade in efficiency but are still better than a space heater. In the worst case they are exactly as efficient as a space heater.
  - shawnz 6y ago
    Sure, but at the point where the efficiency is sufficiently poor, why not run a Bitcoin miner instead of the heat-pump-turned-space-heater? As I understand most heat pumps in cold climates are usually installed with "backup heat" sources for this reason.
    - _Microft 6y ago
      A mining rig that runs only a few days per year when the outside temperature is too low sounds very inefficient. This is the same problem that the plan to store excess renewable energy by producing hydrogen has. If you have the hardware, you would want to have it running as much as possible.
      - deleted 6y ago
        [deleted]
  - carlob 6y ago
    worst case being 0 K outdoor temperature?
    - foepys 6y ago
      Rather 1:1 electricity to heat conversion.
DINKDINK 6y ago
"Pumping water down hill is more efficient than pumping it sideways" The CoP of a heat pump is dependent on the temperature potential across the heat pump. Caution to the reader who thinks one could pump heat from frigid external temperatures into their very warm, high temperature house: the very scenario your post suggests they should be used. Heat pumps are great for increasing thermal potentials and moving heat across them (not for sourcing energy). They're also great for balancing an internal thermal state that is, on-net, in balance (think of a large office building in the morning, one side is being heated by the sun, the other side is frigid -- heat pumps can balance the internal energy demands instead of simultaneously cooling one part of the building and heating the other)
- NDizzle 6y ago
  Heat pumps list that temperature in the documentation of the unit. I think most of the midwest figured this out during the recent cold snap. It turns out the cut off for my heat pump is 10F. I'm in the process of finalizing the installation of a wood stove insert to provide backup heating during the cold months. Switching to all electric feels a little like burning cash to me. If you're in the US, there is an incredible 26% tax credit available on stoves (wood and pellet) that are more than 75% efficient. This covers both the cost of the unit AND installation. It's good for about the next 2 years and went into effect in early Jan. https://www.hpba.org/Advocacy/Biomass-Stove-Tax-Credit https://www.hpba.org/Advocacy/Biomass-Stove-Tax-Credit
- monkeynotes 6y ago
  > Caution to the reader who thinks one could pump heat from frigid external temperatures into their very warm, high temperature house I heat my house with a heat pump. I live in Eastern Canada and we regularly have -20c days and I still heat my house to a comfortable level. Our pump is >=100% efficient all the way down to around -25c at which point it's less and less effective. These pumps are extremely popular around here. We heat during the winter and cool during the summer with the same unit. I consider our heat pumps to be our primary source of heat in our house. We only run the gas furnace if we get into sub -25c days which is not often, we had none this year.

pas 6y ago

That needs good insulation first, or am I missing something? Usually space heaters are warmer, but less efficient. Heat pumps are great if you have time to warm up the space but if it's insulated like an open field, you'll be always cold.

_Microft 6y ago
Why wouldn't one insulate the space? Heating is no end in itself.
zejn 6y ago
Heat pump is essentially a "reverse mount of a refrigerator", putting heat in and throwing cold out. In the worst case, the pump will degrade into a heating element, only outputting heat from electricity (which is what a regular electric heater does). Insulation is not a requirement, but will lower your energy needs to keep a steady temperature.

shawnz 6y ago

They also don't provide very much heat output when it's cold outside

foepys 6y ago
It needs to be really cold. Like -15°C and some go as low as -40°C. They degrade in efficiency but are still better than a space heater. In the worst case they are exactly as efficient as a space heater.
- shawnz 6y ago
  Sure, but at the point where the efficiency is sufficiently poor, why not run a Bitcoin miner instead of the heat-pump-turned-space-heater? As I understand most heat pumps in cold climates are usually installed with "backup heat" sources for this reason.
  - _Microft 6y ago
    A mining rig that runs only a few days per year when the outside temperature is too low sounds very inefficient. This is the same problem that the plan to store excess renewable energy by producing hydrogen has. If you have the hardware, you would want to have it running as much as possible.
    - deleted 6y ago
      [deleted]
- carlob 6y ago
  worst case being 0 K outdoor temperature?
  - foepys 6y ago
    Rather 1:1 electricity to heat conversion.

DINKDINK 6y ago

"Pumping water down hill is more efficient than pumping it sideways" The CoP of a heat pump is dependent on the temperature potential across the heat pump. Caution to the reader who thinks one could pump heat from frigid external temperatures into their very warm, high temperature house: the very scenario your post suggests they should be used. Heat pumps are great for increasing thermal potentials and moving heat across them (not for sourcing energy). They're also great for balancing an internal thermal state that is, on-net, in balance (think of a large office building in the morning, one side is being heated by the sun, the other side is frigid -- heat pumps can balance the internal energy demands instead of simultaneously cooling one part of the building and heating the other)

NDizzle 6y ago
Heat pumps list that temperature in the documentation of the unit. I think most of the midwest figured this out during the recent cold snap. It turns out the cut off for my heat pump is 10F. I'm in the process of finalizing the installation of a wood stove insert to provide backup heating during the cold months. Switching to all electric feels a little like burning cash to me. If you're in the US, there is an incredible 26% tax credit available on stoves (wood and pellet) that are more than 75% efficient. This covers both the cost of the unit AND installation. It's good for about the next 2 years and went into effect in early Jan. https://www.hpba.org/Advocacy/Biomass-Stove-Tax-Credit https://www.hpba.org/Advocacy/Biomass-Stove-Tax-Credit
monkeynotes 6y ago
> Caution to the reader who thinks one could pump heat from frigid external temperatures into their very warm, high temperature house I heat my house with a heat pump. I live in Eastern Canada and we regularly have -20c days and I still heat my house to a comfortable level. Our pump is >=100% efficient all the way down to around -25c at which point it's less and less effective. These pumps are extremely popular around here. We heat during the winter and cool during the summer with the same unit. I consider our heat pumps to be our primary source of heat in our house. We only run the gas furnace if we get into sub -25c days which is not often, we had none this year.