5 ms·

Beyond the other better insulation comments, pairing electric with heat pumps that are SEER 10+ goes a long way to improve heating efficiency. Old resistive he

by dv_dt 7mo ago

Beyond the other better insulation comments, pairing electric with heat pumps that are SEER 10+ goes a long way to improve heating efficiency. Old resistive heaters are 1:1 on energy to heat, while newer heat pumps operate to much lower temperatures, and give you 1:10 or 1:15 electric:heat energy ratios.

bluGill 7mo ago
My heat pump is SEER 19, and it can't heat my house below 25F. I think this is mostly due to it not being large enough - it was sized to cool my house on the hot summer days, and more energy needs to move on the cold winter days.
- coryrc 7mo ago
  SEER, while a useful first-order approximation of efficiency, is for cooling and not heating. HSPF-V is for cold climates. Likely you just don't have a cold-climate heat pump which maintains full capacity down to -10°C (and some a little lower still), even before you get into appropriate maximum capacity.
coryrc 7mo ago
That's not even close to correct. At the design lowest temperature (if <15°C), the very best get 2 COP, but most are 1.5 or lower. The problem is you have to accommodate the worst case. The average of installed units is closer to 2.0 COP average, unfortunately. Multi-head units really drive down efficiency. A single-head Gree Sapphire can do 4-5 COP on average and that's the best you can get, so still nowhere near your guess.
orthecreedence 7mo ago
> 1:10 or 1:15 electric:heat energy ratios Under what circumstances? I've seen higher-end units that do maybe 1:5 in ideal conditions (heating to 68F when the ambient temp is 55F), but never seen units that do 1:10 or 1:15. This was about 2-3 years ago I did this research. Have things improved that drastically in the last few years?
- eldaisfish 7mo ago
  things have not improved. Too many folks here do not understand or care to appreciate the constraints of the real world. Heat pumps are excellent and relatively cheap but have limitations. One of the biggest limitations is that a heat pump's efficiency drops as ambient temperature drops. This is the worst possible situation for heating as the conditions when the risks of losing heat are the highest, are precisely the conditions when these devices are least efficient.
  - timbit42 7mo ago
    As long as they remain more efficient than resistive heaters down to the lowest temperatures you experience, it's a win. Heat pump efficiency is still improving. You can get heat pumps that can handle down to -35°C now with even better ones in the works.
    - eldaisfish 7mo ago
      I'm not questioning the merit of heat pumps. I should know because i have two in Ontario, Canada, one rated to -35 C and the other rated to - 25 C. What i remain opposed to is this persistent idea that heat pumps work in all situations, for all people and for all time. They do not, and heat pumps create a unique set of problems that we might not be fully prepared for.

by dv_dt 7mo ago

bluGill 7mo ago

My heat pump is SEER 19, and it can't heat my house below 25F. I think this is mostly due to it not being large enough - it was sized to cool my house on the hot summer days, and more energy needs to move on the cold winter days.

coryrc 7mo ago
SEER, while a useful first-order approximation of efficiency, is for cooling and not heating. HSPF-V is for cold climates. Likely you just don't have a cold-climate heat pump which maintains full capacity down to -10°C (and some a little lower still), even before you get into appropriate maximum capacity.

coryrc 7mo ago

That's not even close to correct. At the design lowest temperature (if <15°C), the very best get 2 COP, but most are 1.5 or lower. The problem is you have to accommodate the worst case. The average of installed units is closer to 2.0 COP average, unfortunately. Multi-head units really drive down efficiency. A single-head Gree Sapphire can do 4-5 COP on average and that's the best you can get, so still nowhere near your guess.

orthecreedence 7mo ago

> 1:10 or 1:15 electric:heat energy ratios Under what circumstances? I've seen higher-end units that do maybe 1:5 in ideal conditions (heating to 68F when the ambient temp is 55F), but never seen units that do 1:10 or 1:15. This was about 2-3 years ago I did this research. Have things improved that drastically in the last few years?

eldaisfish 7mo ago
things have not improved. Too many folks here do not understand or care to appreciate the constraints of the real world. Heat pumps are excellent and relatively cheap but have limitations. One of the biggest limitations is that a heat pump's efficiency drops as ambient temperature drops. This is the worst possible situation for heating as the conditions when the risks of losing heat are the highest, are precisely the conditions when these devices are least efficient.
- timbit42 7mo ago
  As long as they remain more efficient than resistive heaters down to the lowest temperatures you experience, it's a win. Heat pump efficiency is still improving. You can get heat pumps that can handle down to -35°C now with even better ones in the works.
  - eldaisfish 7mo ago
    I'm not questioning the merit of heat pumps. I should know because i have two in Ontario, Canada, one rated to -35 C and the other rated to - 25 C. What i remain opposed to is this persistent idea that heat pumps work in all situations, for all people and for all time. They do not, and heat pumps create a unique set of problems that we might not be fully prepared for.