this post was submitted on 24 Nov 2023
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‘You can walk around in a T-shirt’: how Norway brought heat pumps in from the cold | Device installed in two-thirds of households of country (www.theguardian.com)
submitted 11 months ago by [email protected] to c/[email protected]
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[–] [email protected] 23 points 11 months ago* (last edited 11 months ago) (5 children)

I've seen a lot of articles claim heat pumps don't work well below -15c, but they never mention there are ways around that. I live in Canada in an area that regularly gets much colder and a lot of people around here have heat pump systems... the only difference is instead of the other side of the heat pump being outside, we bury them underground below the frost line. (Geothermal)

It does drive the cost up somewhat, but they still end up paying for themselves in the long run. Added bonus is in the summer, most system are reversible and will also cool your house much cheaper than traditional ac units.

[–] [email protected] 4 points 11 months ago (1 children)

Maybe part of the problem is my fear of installing anything "for the long run" because not only do I not want to live here 30 years from now, I can't imagine myself happy anywhere in the US for a period of 30 years straight.

[–] [email protected] 5 points 11 months ago

That’s for sure a reason not to do it, but in theory it adds to the value and therefore sale price of your home

[–] [email protected] 3 points 11 months ago (2 children)

There's also different kinds of heat pumps. The most expensive version is vertical bore, but it also does better in colder climates. The term "heat pump" is kind of confusing to the average person, because it represents several different ways/layouts to accomplish the same goal.

Additionally, even if it can't keep up in extreme cold weather (hypothetically), imagine if you have a system that can heat your home to 15C, and then you have supplemental heating on top of that. You'd still save money and energy over having traditional heating methods.

[–] [email protected] 3 points 11 months ago* (last edited 11 months ago)

It's all basically the same type of systems, it just varies as where they pull/send to. The vertical bore style is just straight down instead of loops in your backyard for the installations where there isn't much yard to work with. It takes more specialized equipment because you're drilling rather than just burying lines, hence most of the added costs.

Where I live it drops into the -30 to -40c degree temps and properly installed geothermal systems have no problems with it.

[–] [email protected] 2 points 11 months ago

We have a heat pump, and it seems to work just fine down to about -25°C, even though we do not have an inground circuit, just a device that looks like an air conditioning heat exchanger (i.e. a cube sitting beside the house).

[–] MountainGoat 1 points 11 months ago (2 children)

Aren't there other supplemental heat options, too? So if it's "too cold" they can put a gas or electric warmer on the system to bring the temp up. With their 200%+ efficiency it would be like running a space heater.

[–] [email protected] 1 points 11 months ago

Yes, I have an air source heat pump (basically a reversible air conditioner) with typical coils in an air handler with electric resistive heating coils as backup. Essentially, they can work with any backup system, whether it's an electric or gas furnace, or other space heating units elsewhere.

[–] [email protected] 1 points 11 months ago

Ya you could... you'd be better off though just getting a system that suits your location though, but the initial cost is usually the biggest issue. I live where it commonly gets in the -30 to -40c temps, and I know of 25,000 square foot shops with geothermal pumps that stay nice and warm all winter.

[–] [email protected] 1 points 11 months ago

Ground source heat pumps are not air source heat pumps. They're not an option for people without either very large gardens for horizontal installation, or access for very large machinery to dig the holes to install them vertically.

The claims you have seen likely came from a pro-carbon lobbyist or someone with a badly-installed heat pump. Air source isn't as efficient as ground source but they are cheaper to run, as long as the house is reasonably well-insulated, has large enough radiators or underfloor heating, and enough air circulates around the pump.

[–] [email protected] 1 points 11 months ago (1 children)

Unless you have a constant heat source (flowing groundwater), you need to pump heat back into the ground in summer or the system will "freeze up" after a few years. If the heat battery of the ground isn't being recharged, it'll eventually die.

[–] [email protected] 2 points 11 months ago* (last edited 11 months ago)

Yup we had that problem at a large shop once. The system was still working but it was really struggling one winter. They were previously using heat only (floor heat), so that spring they installed a few radiators with fans for cooling to push more heat back into the ground. Worked great ever since.

Thermal mass storage system in a way.

[–] [email protected] 6 points 11 months ago (1 children)

I live in a shitty house from the 50s in Poland, poorly insulated AND I walk around the house on a t-shirt if I want... the problem is the energy I have to spend. Heat-pumps are not a miracle if your house is poorly insulated.

[–] pigup 4 points 11 months ago (1 children)

I've been remodeling my house one room at a time, I'm taking insulation very seriously and putting as much as I can. The rooms that I've remodeled are so hot during winter while rest of house is freezing, quite annoying for my HVAC system actually, but interesting how much money is just flying away through the walls

[–] [email protected] 2 points 11 months ago

If I may suggest you focus on air tightness as well. Insulation isn't very effective with air flowing through it. If you've worn a fleece jacket on a windy day you'll know what I mean.

That, and vapour penetration through a poorly sealed envelope can lead to moisture issues.