- cross-posted to:
- hackernews@derp.foo
- cross-posted to:
- hackernews@derp.foo
Heat pumps can’t take the cold? Nordics debunk the myth::By installing a heat pump in his house in the hills of Oslo, Oyvind Solstad killed three birds with one stone, improving his comfort, finances and climate footprint.
It really depends on the type of heat pump. Air-sourced heat pumps generally don’t produce heat below -30C and below -10C they generally lose enough efficiency that you’re better off using electric baseboard heating.
My air sourced heat pump keeps my house warm just fine in the Finnish winter where temperatures of -30C aren’t unheard of. I’m not exactly sure how it works, but I assume there’s coils that’ll produce the heat by electricity if nececcary, making it at worst as efficient as direct electric heating, which is what I’d use otherwise. Here like every other house has a heatpump like that and I don’t remember hearing anyone ever complaining that they’re not working.
The argument is bullshit in totality. But… When the supplemental electric heating coils come on, it is less efficient ON THAT DAY, than the alternative electric options. But, like I said, in totality, it’s more effective over a month, and certainly better over the course of a year. It’s a matter of people with an agenda cherry picking the 9 days a year in which it is less efficient and pretending that the other 354 days don’t count.
It depends what you mean by the alternative electric options. Electric resistance heating is 100% efficient and that’s what my heatpump effectively is when it gets cold enough. It’s not less efficient than wall mounted electric radiators even when it drops to -30C. You just lose the efficiency of a heatpump for that time.
Exactly - people somehow fail to understand that Heat Pumps, by necessity, are always more efficient than 100% of an equivalent electric solution.
I suppose if electric heat is the primary option then sure. Around here though natural gas is pretty much ubiquitous and the cost per joule is a heck of a lot lower than electricity. About $6/GJ for natural gas, compared to about $42/GJ for electricity. Would need a pretty efficient heat pump to see the cost savings in my area.
There are heat pumps now that use gas to do the supplemental heat. Those are the best possible option. They are equally efficient to a gas furnace when supplementing, and even cheaper when not.
I’m sure there’s applications where that’s true, but then you’re essentially talking about having a gas furnace plus a heat pump, so you’re installation cost is close to the sum of both systems. Energy rates vary by region, but around here electricity is about 7 times the cost of gas, so a heat pump running at a coefficient of performance around 3 would still cost twice as much to run as a natural gas furnace, it would be cheaper to just turn off the heat pump altogether and only use that “supplementary” heat.
When I was looking at new heat pumps the hybrid ones were between 500 & 1000 more than the equivalent electric ones.
It’s not a sperate unit, it just has a gas heater in place of the electric supplemental coils.
Except that electric heating is always 100% efficient, and that’s what a heat pump falls back to. If anything it will still be more efficient than baseboard heating simply due to it having a fan to better distribute the heat (equivalent to an electric furnace with ducting). The only argument that makes sense is when comparing costs with other heat sources like natural gas, which is a whole other topic.
Interesting. A close friend is an engineer who designs HVAC systems (industrial but regardless knowledgeable).
He’s told me that the heat pump would pull more power on those days than an equivalent electric only system.
My heat pump definitely uses a lot of power when it’s cold.
I wish I had access to the gas based supplemental heating for it. Economically that seems like the best option.
I think mine is undersized and close to 20 years old now. Reading your response is yet another reason I have to go through with upgrading everything.
Generally you’d have a backup heat source with an air-to-air heat pump for those really cold days like -15C and colder, like a gas furnace or a heating element unit inside (like with electrical coils). Air-to-air heat pumps are more efficient on warmer days, on colder days they would be less efficient but you’d still have a backup heat source so it would still “work”, so the article is still somewhat correct in that sense.
Also, electric baseboard heaters can be quite a bit louder than forced-air systems with a heat pump, so you’d still be better off with a heat pump in those cases.