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Heat pumps twice as efficient as fossil fuel systems in cold weather, study finds
(www.theguardian.com)
this post was submitted on 12 Sep 2023
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Technology
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The coldest temperature ever recorded in the UK is -27. That's right around the inflection point for where heat pumps become less efficient than electric heaters. Until the gulf stream fails, the UK is pretty safe to use heat pumps everywhere.
So yeah, going 100% air-source heat pump if you're area regularly spends time around -30°C (-22F) might not be the best idea. Though even the last report you cited said it might be 1.5-2x as efficient as resistive heating. And that Site 1 with bad COPs was because they manually lowered the fan speed...
There are vanishingly few people who live in areas with weather consistently below -30C. I've been seeing that kind of concern trolling all over the place in the past year or so, and they always have the same song and dance about low efficiency in extreme cold - technically correct, but taken as part of the bigger context, so niche as to be practically irrelevant. Yeah, if you live in Yakutsk you won't want to rely only on a heat pump. Big fuckin' deal - the other 99.5% of people on earth can benefit greatly.
Edit: I wouldn't be susprised if this is the exact same guy I once argued with on Mastodon, actually. He was German too.
Get a heat pump with resistive (electric) defrosting, not one that defrosts by running like an AC.
But only for the 4 weeks a year you spend in unusually cold weather, the other 48 it's more efficient.
It's not like truly arctic places are a reasonable application but the overwhelming majority of our population lives south of Quebec and north of Wellington. So it's not a relevant point, everyone in the Arctic can just use resistive heating or burn fuel, and if we get everything else on heat pumps we reduce our enegy use by a factor of 2-3 regardles.
Sure, for a few days a year it might get as bad as resistive heating. How horrible! So you don't get 3.2x total throughout the year, you get 3.1x. It's a non-issue.
I'll chime in here since I own 2 heat pumps and live in a cold climate (often below 20C). Our house is heated with 100% electricity and after installing heat pumps our power bill dropped by about 18%. That includes all electricity, not just heating, so the gain in heating efficiency was very considerable.
The Guardian is a UK publication.
"Generally" is the wrong way to approach this. What you should be looking at is the specific capabilities of the actual system that you are considering installing. Some of them can go much colder.
If the Mitsubishi FE18 isn't efficient in your climate... then don't buy that unit. Simple.
If it's really cold where you are... then you could consider a ground source heat pump instead one that uses air as a heat source. The ground doesn't get anywhere near cold to have efficiency issues no matter where you are in the world and ground source heat pumps don't cost all that much... though they do require a bit of digging.
Also, if your heat pump is inefficient for a couple really cold weeks a year... oh well. You're still coming out ahead because it's very efficient the other 50 weeks a year. It's not like they stop working at extremely cold temperatures, they just produce a bit less heat than you might like for the amount of power consumed. Maybe they're "only" 80% efficient instead of 600% efficient... you know what else is 80% efficient? Heating with gas.
I live in Finland. Heat pump is the only source of heat in my house.
Some of the stations in Antarctica use heat pumps. They have been proven to work effectively at -53°C (-64°F) and do so reliably.
Are they more efficient at more reasonable temperatures? Yes. But they still work even when it's very cold outside.
How well a heat pump works in cold temperatures obviously depends what temperatures it was designed to operate at. Don't waste your money on a model that is designed to operate in a different climate. In fact a lot of heat pumps aren't even capable of heating at all - they can only output cold air (which they can do even if it's stinking hot outside by the way).
It can go down to -30C (-22f) sometimes or even below that
Yeah averages are way higher than that. My point just was that saying they don't work in cold climates isn't quite true. Yes, there are locations with way colder climates than this but if Finland isn't considered a "cold climate" then I don't know what is.
Heat pumps are super common here. Many houses just have a electric resistance heating so people switch to heat pumps to save on electricity.
Are you intimately familiar with the inner workings of your heatpump? Nearly all heatpumps in a cold climate have backup heat built in and it would automatically switch to backup when it gets too cold outside. -30C is well into the too cold category for it to function as a heatpump alone
Which makes the argument that heat pumps don't work in the cold completely wrong from a user perspective.
Yeah I have no idea. The alternative would be electric radiators anyways so in most cases that wouldn't make a difference anyways. Temperatures that low are quite rare - maybe just a handful of nights a year. Generally it stays around -10C
What happens when the power goes out
The same thing that happens when you have electric or gas heating. It stops working, because none of those work without electricity nowadays. Hell if you have a coal/wood burner for central heating chances are it doesn't work without electricity either.
how often do you think the power goes out in finland
How often does it got out in Germany At least Finland built a Nuclear reactor to power most of the country unlike Germany which shut all their's down
afaik power never really goes out in western europe unless something happens to the infrastructure (e.g. lightning strike or tree falling on a power line), what instead happens when we run out of generation capacity is that prices skyrocket.
In my house? Pretty much never. We have solar as well as a grid connection and can connect a generator as well.
In fact, I even have a second stand alone portable solar system that we take camping. It's not powerful enough to heat a house... but it is powerful enough for pretty much everything else. And I can heat my house with a fire if it came to that.
Redundancy is the name of the game if you're worried about reliability.
Well it obviously stops working and unless you have some other means of heating your house you're kinda fucked and can only hope it comes back on soon as it generally does.
So? It is basically always as efficient as resistive heating at its worst, and the vast majority of the time it is massively more efficient. And even then they can remain more efficient even as low as -25C and might need resistive heating backup at places that get below that. But even in places that can dip below that they are often not that cold all year round. So overall throughout the year they are way more efficient on the majority of days even if you need a less efficient backup system.
We really need to think of the whole situation rather than just focus on the but sometimes part of the problem. Yes, sometimes they dont work as well. But overall through a year for the vast majority of places a heat pump can be all you need and is a lot more efficient than other heating systems.
And what point does that happen? According to the article and other sources say similar things:
And the lowest recorded temperature in the UK since 1961 is -27.2 °C. So the times you need to fall back to resistive or other backup systems is 0% of the time. And what do you count as a cold climate? is 0C cold? or -10C? -20C? I know many people that would say yes at any other those and I bet there are others that live in places that go way lower. Yeah, what you said is technically true, but without these numbers is almost a meaningless statement. In the UK, and most of europe this article is basically saying that heat pumps are more effective than other sources of heat even at colder temperatures and it takes extremes before they require alternative heating methods.
The way you worded your post it makes it sounds like on a average coldish winters day heat pumps become useless and there is little point in having them. Even if that is not what you intended.
Most modern heat pump systems account for that and have electric heating/defrosting built-in for those few cold days a year.
Also it's not like you have to remove your old heating system*; you can just plumb in the heat pump into your central heating and have cut off valves for the original system, so you can still use it as a backup.
*) unless your government is retarded and in order to get subsidies they require you to uninstall it
Quite frankly, in really really cold places (the only places where your criticism applies) you should not have a single source of heat period. You always need a backup in case one of your heat sources fails. It does not have to be able to heat your house a lot, just keep it stable above freezing, but you do need a backup.