Last I read, which was years ago, was they still struggle under -20C. Which is not abnormal for many places in Canada. How do these perform in wicked cold times?
unless I am very much mistaken this is only true for air source heat pumps. If you’re in a cold environment I would expect you’d want a ground source heat pump instead, although the installation cost for that will be significantly higher than air source.
they still struggle under -20C. Which is not abnormal for many places in Canada
Yes, but that’s why heat pumps in this country are typically paired with auxiliary electric heat. The heat pumps still contributes some amount, even at -30 or below, but the electric “tops up” the pre-warmed air that the heat pump makes.
And that is only really needed for a couple of months out of the year, even in places like Winnipeg or Edmonton.
20-30 years ago, the heat pump technology wasn’t as capable, and couldn’t do the job as well, but they have improves quite a lot since then.
Yes, but that’s why heat pumps in this country are typically paired with auxiliary electric heat.
Yes, and although it’s not very efficient to have auxiliary electrical heat, that’s a small percent of the overall year.
If you live in a home that hits -20C for 20 days per year, that’s really cold! But you’ll probably need the heater on for about 180 days per year at that point. Putting up with less efficiency for 20-30 days per year is still a net gain if the other 150 days of heating makes up for it.
This is not the whole story because not every heating day is equally cold. I have a high end cold climate heat pump in Colorado (which works great btw). I use about 1/3 of my total annual heating energy in January, despite heating for >6 months of the year. I’ll use 10% of my annual energy budget for a long weekend if its -10F, and that’s all heat pump (I don’t even have backup strip heat). It would be 20% if i was using electric resistnace for those 4 days. Electric resistance is really not great, so folks really should get the best heat pumps they can that cover the coldest normal days. It’s fine to install strips as a true backup but you’re going to have some very high bills and high carbon if you’re using it 20-30 days/year. If its hydro/nuclear power you’ll still come ahead on carbon but that’s not the case everywhere.
Yeah but if some direct combustion of a fossil fuel is cheaper than electricity, then the actual dollars per unit heat will be cheaper with a fossil fuel source.
but the electric “tops up” the pre-warmed air that the heat pump makes.
Is the heater at the hot end? The reason they crap out is that they can no longer move and vapourise their coolant, so I’d expect it to be somewhere else, probably the cold end.
I have a heat pump and furnace combo. The heat pump works extremely well down to around -10C. Below that it takes a very long time to move the needle by half a degree. The furnace doesn’t kick in until the thermostat sees the house temperature trending in the opposite direction it’s attempting to achieve.
Unfortunately, its method of determining the time gradient of temperature is rather moronic and doesn’t take the temperature schedule into account. This means every morning when the schedule calls for higher daytime temperatures (even by just half a degree) the thermostat freaks out thinking that the house is cooling rapidly and kicks on the furnace to bring up the temperature.
This causes the system to needlessly run the furnace every single morning. It annoys the hell out of me but I don’t know what to do about it. Aftermarket thermostats aren’t very common around here (Canada).
Have you checked home automation forums? Some users are fanatics about tweaking stuff. Maybe there is a method or override option.
Or see if you can get manufacturer on the phone.
My issue is home insurance and HVAC regulation in Canada. I don’t know what is legal and what isn’t as far as HVAC system modifications go, given that I’m not a licensed HVAC technician. Doing my own home automation mods badly could damage or destroy either my heat pump or furnace, resulting in thousands of dollars in repair bills. Or it could jeopardize my home insurance in case of a fire and result in even greater financial losses, even if my modifications were only tangentially related to the cause of the fire.
There are a variety of aftermarket thermostats available at Canadian Tire, many of which are quite good. The Home Automation enthusiasts seem to be big fans of ecobee, IIRC, and I have seen ecobee thermostats at CT.
That, and some heat pumps are better than others. The ones that use geothermal (lines run underground below the frost line) are more expensive but don’t have much issue with the cold.
Many are designed for extreme temperatures now, but they are not efficient in such temperatures due to the properties of the refrigerants available. It will usually still run, but will run longer than usual and may not be able to keep up with heat demand. During a cold snap, might run continuously and may need frequent defrost cycles which further reduces efficiency and heating capacity. How cold they can/should go depends on things like sizing, refrigerant, building insulation, solar heat gain, and other factors. In a country like Canada, air source heat pumps will always be installed with a backup heat source. In Canada, that is most commonly the same natural gas furnace that the house was always originally equipped with, while the heat pump replaces the air conditioning unit, but backup heat can also be resistive electric, heating oil, wood, and more, and a decent thermostat will have an outdoor air sensor that can detect an appropriate outdoor conditions at which to switch from heat pump to backup/“emergency” heat when needed, and then back to heat pump when conditions permit.
In my experience, my heat pump provides about 90% of my heating from fall to spring. Only a few severe cold snaps put the heat pump on the bench for a few days switching over to emergency heat completely, and most of the winter it runs frequently to continuously to maintain consistent temperatures and only needs a short and occasional boost from the furnace. The gas backup is also nice peace of mind in case of a prolonged power outage due to a potential ice storm, as the furnace blower and electronic controls can easily be run off a small battery pack or generator for a very long time.
Last I read, which was years ago, was they still struggle under -20C. Which is not abnormal for many places in Canada. How do these perform in wicked cold times?
unless I am very much mistaken this is only true for air source heat pumps. If you’re in a cold environment I would expect you’d want a ground source heat pump instead, although the installation cost for that will be significantly higher than air source.
Mine works fine.
Yes, but that’s why heat pumps in this country are typically paired with auxiliary electric heat. The heat pumps still contributes some amount, even at -30 or below, but the electric “tops up” the pre-warmed air that the heat pump makes.
And that is only really needed for a couple of months out of the year, even in places like Winnipeg or Edmonton.
20-30 years ago, the heat pump technology wasn’t as capable, and couldn’t do the job as well, but they have improves quite a lot since then.
Yes, and although it’s not very efficient to have auxiliary electrical heat, that’s a small percent of the overall year.
If you live in a home that hits -20C for 20 days per year, that’s really cold! But you’ll probably need the heater on for about 180 days per year at that point. Putting up with less efficiency for 20-30 days per year is still a net gain if the other 150 days of heating makes up for it.
This is not the whole story because not every heating day is equally cold. I have a high end cold climate heat pump in Colorado (which works great btw). I use about 1/3 of my total annual heating energy in January, despite heating for >6 months of the year. I’ll use 10% of my annual energy budget for a long weekend if its -10F, and that’s all heat pump (I don’t even have backup strip heat). It would be 20% if i was using electric resistnace for those 4 days. Electric resistance is really not great, so folks really should get the best heat pumps they can that cover the coldest normal days. It’s fine to install strips as a true backup but you’re going to have some very high bills and high carbon if you’re using it 20-30 days/year. If its hydro/nuclear power you’ll still come ahead on carbon but that’s not the case everywhere.
I mean, a resistive electric heater is still (“just”) 100% efficient.
Yeah but if some direct combustion of a fossil fuel is cheaper than electricity, then the actual dollars per unit heat will be cheaper with a fossil fuel source.
True.
Is the heater at the hot end? The reason they crap out is that they can no longer move and vapourise their coolant, so I’d expect it to be somewhere else, probably the cold end.
The ones I’ve seen, the aux heat is in the duct airflow after the hear exchanger.
I have a heat pump and furnace combo. The heat pump works extremely well down to around -10C. Below that it takes a very long time to move the needle by half a degree. The furnace doesn’t kick in until the thermostat sees the house temperature trending in the opposite direction it’s attempting to achieve.
Unfortunately, its method of determining the time gradient of temperature is rather moronic and doesn’t take the temperature schedule into account. This means every morning when the schedule calls for higher daytime temperatures (even by just half a degree) the thermostat freaks out thinking that the house is cooling rapidly and kicks on the furnace to bring up the temperature.
This causes the system to needlessly run the furnace every single morning. It annoys the hell out of me but I don’t know what to do about it. Aftermarket thermostats aren’t very common around here (Canada).
Have you checked home automation forums? Some users are fanatics about tweaking stuff. Maybe there is a method or override option. Or see if you can get manufacturer on the phone.
My issue is home insurance and HVAC regulation in Canada. I don’t know what is legal and what isn’t as far as HVAC system modifications go, given that I’m not a licensed HVAC technician. Doing my own home automation mods badly could damage or destroy either my heat pump or furnace, resulting in thousands of dollars in repair bills. Or it could jeopardize my home insurance in case of a fire and result in even greater financial losses, even if my modifications were only tangentially related to the cause of the fire.
Understood, the manufacturer may have a firmware update to solve the issue you mentioned
That’s a good point. I should look into that. It does have the ability to connect to the thermostat with an app but I never tried that.
There are a variety of aftermarket thermostats available at Canadian Tire, many of which are quite good. The Home Automation enthusiasts seem to be big fans of ecobee, IIRC, and I have seen ecobee thermostats at CT.
I’ll check them out. I once applied for a job at ecobee without knowing what they did!
Central heat pumps have built in electric heat in cases the heat pump alone isnt sufficient.
Even if the heat pump isnt enough all the time, its still better than heating with oil, electricity, gas, etc. exclusively.
It isnt an all or nothing situation.
That, and some heat pumps are better than others. The ones that use geothermal (lines run underground below the frost line) are more expensive but don’t have much issue with the cold.
Last conversation I had on Reddit years ago a guy in Ottawa had data that showed that he was drawing heat during near -40C.
Some heat pump models can work at -30C
Many are designed for extreme temperatures now, but they are not efficient in such temperatures due to the properties of the refrigerants available. It will usually still run, but will run longer than usual and may not be able to keep up with heat demand. During a cold snap, might run continuously and may need frequent defrost cycles which further reduces efficiency and heating capacity. How cold they can/should go depends on things like sizing, refrigerant, building insulation, solar heat gain, and other factors. In a country like Canada, air source heat pumps will always be installed with a backup heat source. In Canada, that is most commonly the same natural gas furnace that the house was always originally equipped with, while the heat pump replaces the air conditioning unit, but backup heat can also be resistive electric, heating oil, wood, and more, and a decent thermostat will have an outdoor air sensor that can detect an appropriate outdoor conditions at which to switch from heat pump to backup/“emergency” heat when needed, and then back to heat pump when conditions permit.
In my experience, my heat pump provides about 90% of my heating from fall to spring. Only a few severe cold snaps put the heat pump on the bench for a few days switching over to emergency heat completely, and most of the winter it runs frequently to continuously to maintain consistent temperatures and only needs a short and occasional boost from the furnace. The gas backup is also nice peace of mind in case of a prolonged power outage due to a potential ice storm, as the furnace blower and electronic controls can easily be run off a small battery pack or generator for a very long time.
See here how Norway is doing it: https://www.theguardian.com/environment/2023/nov/23/norway-heat-pumps-cold-heating