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I don't understand why anyone would be worried their heat pump isn't going to work in winter. I've never seen a heat pump installation that didn't include an em

by causi 4y ago

I don't understand why anyone would be worried their heat pump isn't going to work in winter. I've never seen a heat pump installation that didn't include an emergency resistive heater.

SigmundA 4y ago
It's not so much a worry as an efficiency thing. If your in a cold climate that needs resistive heat its a lot less efficient to burn natural gas at power plant at 50-60% then turn to heat with a resistor in your house, than to burn it in your house at 80-90% efficiency. Thing about a heat pump is it basically turns into a resistive heater once it can't capture any outside heat, then you just have heat of compression. This changes with a lot of renewable and nuclear power, but also heat pumps that can keep operate rating above unity in those cold temps really start making sense.
bigdog90 4y ago
In my house we only have electric heat available. When it gets too cold, the heat pump no longer keeps up and the resistive heater in the furnace turns on. It is more expensive to use the coils than the heat pump. It is important to understand the environment it is running in to accurately predict your energy costs. The previous owner should have installed one that could run in colder temperatures.
cwingrav 4y ago
Mine cuts off at 35F and I have to manually switch on the oil. I live where winter is normally below 35 at night. Very annoying system. (I didn’t pick it)
melolife 4y ago
So there are two problems as I see it: Firstly you see analyses like these where the author goes "see, heat pumps work fine in cold climates, look at these success stories!", and then proceeds to list a bunch of places that aren't particularly cold. People think Norway is cold, but if you look at Wikipedia then the average daily low for Tromso (a random northerly Norgewian municipality) in January is -5.6C, with a record low of -18C. Compare this with Calgary, a relatively southerly prairie city with an average low of -13.2C and a record low of -44C. The second problem is that they say "don't worry, if it actually gets cold it switches to resistive heat!" The problem here is that the extremes absolutely matter, because this is when demand is highest. If a prairie province/state switches everyone to heat pumps, then your grid had better actually be designed for everyone to be using resistive heat for weeks at a time, because that's exactly what's going to happen when you need it most.
- kevstev 4y ago
  Yeah but there are other solutions as well. When these articles come up people seem so obsessed about finding some gotcha! and why it won't work for them in certain situations, its strange to me. Heat pumps are absolutely a better technology that will recoup their higher costs within 10 years for just about everyone (yes, not everyone... just about everyone). Find me a guaranteed 10% return in the market these days please, I will thank you enormously. I am looking into this right now in the NYC area. My ~13 year old HVAC system has a refrigerant leak in the AC component. Heat pumps that work in the very cold are considerably more expensive. Except... I have a perfectly fine gas powered furnace that will likely last another 20 years, if not more. So we are going to leave the furnace in, only have it kick on if the temps get too cold and... done. This may not be true in all environments, but in the Northeast, electrical demand is far far higher in the summer than the winter. Yeah, in the super cold north, maybe they aren't a home run- yet- but they get better every year, but this whole ludditeism and resistance to change is very strange for a place like HN.
balderdash 4y ago
I had a heat pump that seemed to work well above 10-20f (which was <10% of the heating days), but you could see the aux heat cost in your electric bill if you had a bunch of really cold days!
hombre_fatal 4y ago
Surely your last sentence answers your question if most heat pumps come equipped with a backup heat source that uses a different mechanism. Why wouldn’t people ask questions then about the limits of the heat pump?

by causi 4y ago

I don't understand why anyone would be worried their heat pump isn't going to work in winter. I've never seen a heat pump installation that didn't include an emergency resistive heater.

SigmundA 4y ago

It's not so much a worry as an efficiency thing. If your in a cold climate that needs resistive heat its a lot less efficient to burn natural gas at power plant at 50-60% then turn to heat with a resistor in your house, than to burn it in your house at 80-90% efficiency. Thing about a heat pump is it basically turns into a resistive heater once it can't capture any outside heat, then you just have heat of compression. This changes with a lot of renewable and nuclear power, but also heat pumps that can keep operate rating above unity in those cold temps really start making sense.

bigdog90 4y ago

In my house we only have electric heat available. When it gets too cold, the heat pump no longer keeps up and the resistive heater in the furnace turns on. It is more expensive to use the coils than the heat pump. It is important to understand the environment it is running in to accurately predict your energy costs. The previous owner should have installed one that could run in colder temperatures.

cwingrav 4y ago

Mine cuts off at 35F and I have to manually switch on the oil. I live where winter is normally below 35 at night. Very annoying system. (I didn’t pick it)

melolife 4y ago

So there are two problems as I see it: Firstly you see analyses like these where the author goes "see, heat pumps work fine in cold climates, look at these success stories!", and then proceeds to list a bunch of places that aren't particularly cold. People think Norway is cold, but if you look at Wikipedia then the average daily low for Tromso (a random northerly Norgewian municipality) in January is -5.6C, with a record low of -18C. Compare this with Calgary, a relatively southerly prairie city with an average low of -13.2C and a record low of -44C. The second problem is that they say "don't worry, if it actually gets cold it switches to resistive heat!" The problem here is that the extremes absolutely matter, because this is when demand is highest. If a prairie province/state switches everyone to heat pumps, then your grid had better actually be designed for everyone to be using resistive heat for weeks at a time, because that's exactly what's going to happen when you need it most.

kevstev 4y ago
Yeah but there are other solutions as well. When these articles come up people seem so obsessed about finding some gotcha! and why it won't work for them in certain situations, its strange to me. Heat pumps are absolutely a better technology that will recoup their higher costs within 10 years for just about everyone (yes, not everyone... just about everyone). Find me a guaranteed 10% return in the market these days please, I will thank you enormously. I am looking into this right now in the NYC area. My ~13 year old HVAC system has a refrigerant leak in the AC component. Heat pumps that work in the very cold are considerably more expensive. Except... I have a perfectly fine gas powered furnace that will likely last another 20 years, if not more. So we are going to leave the furnace in, only have it kick on if the temps get too cold and... done. This may not be true in all environments, but in the Northeast, electrical demand is far far higher in the summer than the winter. Yeah, in the super cold north, maybe they aren't a home run- yet- but they get better every year, but this whole ludditeism and resistance to change is very strange for a place like HN.

balderdash 4y ago

I had a heat pump that seemed to work well above 10-20f (which was <10% of the heating days), but you could see the aux heat cost in your electric bill if you had a bunch of really cold days!

hombre_fatal 4y ago

Surely your last sentence answers your question if most heat pumps come equipped with a backup heat source that uses a different mechanism. Why wouldn’t people ask questions then about the limits of the heat pump?