Heat pumps are great, but under -15C, they’re really, really inefficient.
I think you’re working off old data, or you’re misunderstanding the article where they say air-source heat pumps start to lose efficiency at ~15°C. My unit, installed just over a year ago is rated for a COP of at least 1.72 at 0°F (-17.78°C) when the inside temperature is 80°F (26.67°C). And as I said, newer units are getting better and better.
I have a newer 23 SEER pump now, and it’s pretty terrible at that temperature. The draw is approaching resistive at -20 and beyond that, well, don’t even bother. If I compare costs to running my backup furnace past -15 vs the electricity costs to force it to work at that temperature, I turn off the heat pump.
Yes, for about 90% of the work these pumps do, they are efficient and cost effective, as well as cooling in the summer. But this blue-sky thinking that they can replace NG heating in places like the Canadian Prairies is a pipe dream at this time.
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The expense for ground source heat pumps, especially in the city, would be ridiculous.
Heat pumps are great, but under -15C, they’re really, really inefficient. And Winnipeg is very often much colder than that.
I think you’re working off old data, or you’re misunderstanding the article where they say air-source heat pumps start to lose efficiency at ~15°C. My unit, installed just over a year ago is rated for a COP of at least 1.72 at 0°F (-17.78°C) when the inside temperature is 80°F (26.67°C). And as I said, newer units are getting better and better.
I have a newer 23 SEER pump now, and it’s pretty terrible at that temperature. The draw is approaching resistive at -20 and beyond that, well, don’t even bother. If I compare costs to running my backup furnace past -15 vs the electricity costs to force it to work at that temperature, I turn off the heat pump.
Yes, for about 90% of the work these pumps do, they are efficient and cost effective, as well as cooling in the summer. But this blue-sky thinking that they can replace NG heating in places like the Canadian Prairies is a pipe dream at this time.