Canada

Mine is rated for -25, which where i live in southern Ontario has been reached 3 times in 50 years (wind chill doesn't count remember). And while I haven't had a heat pump for one of those days I don't think it would be a problem, after all the efficiency doesn't just drop to 0, it just doesn't work as well for that one day and my house could stay a safe level of warm for a day or 2 without heat anyway.

Despite this I am required to have an auxiliary heat source, so I get charged 30 dollars a month just for a gas hook up I haven't used.

A lot of heat pumps have normal electrical heating as a backup as well.

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.

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.

Last conversation I had on Reddit years ago a guy in Ottawa had data that showed that he was drawing heat during near -40C.

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.

Some heat pump models can work at -30C

Norway has worked it out. I am sure Canada can. Ground source is one option, or a second heater for the few very cold days.

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).

See here how Norway is doing it: https://www.theguardian.com/environment/2023/nov/23/norway-heat-pumps-cold-heating

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.

Gas furnaces achieve about 96-98% efficiency. Heat pumps achieve 300-400%. So you have to factor that in.

There's still a cost difference but the hope is for governments to start supporting serious nuclear energy to drive down electric costs. It'll take time but natural gas will become less economical as decades go on especially with investments.

Yeah, depends where you live. Saskatchewan is the worst place, Quebec is the best.

120 for most applications but 240 for things like stoves, dryers, heat pumps, car chargers, etc.

Residential Outlets are 120V which most household small appliances and lights plug in. Oven ranges, laundry dryers, air conditioning units use 240V. Essentially they have two inverted phases: -120V, +120V to supply 240V across the two ends, usually with a NEMA 14-30 or 14-50 type plug.

Mostly 120V, but some appliances require 240V.

Thermostats typically use 24V for controls which I believe is considered low-voltage wiring.