Oxford study proves heat pumps triumph over fossil fuels in the cold::Published Monday in the scientific journal Joule, the research found that heat pumps are two to three times more efficient than their oil and gas counterparts, specifically in temperatures ranging from 10 C to -20 C.
The Oxford study is really good. But I can’t say the same about this article.
A COP of ~2 is not great for a heat pump, calling this a triumph is really weird. But from a journalist saying that a COP above 1 means the heat pump “creates energy”, I am not sure I should have expected more.
But what’s great is that this COP of 2, while bad, is not catastrophic. That’s still in territory where gas boilers are more cost efficient that a heat pump, but unless you are living in a place that is consistently under -10C for several months, then a heat pump has overall lower running costs than a gas boiler. And you are starting to hit pretty northern territories with this.
What’s important is also to be able to store heat during the day so that the heat pump runs at its most efficient time. But that can unfortunately coincide with the higher consumption time, so the timing needs to be adjusted properly to avoid using it during consumption peaks.
Heat pumps are A/C in reverse. It makes total sense instead of using fire to heat air.
brb putting in my window unit from the outside
You think you are being a smartass but that’s exactly what heat pumps do. The only functionality difference between an AC unit and a heat pump is a reversing valve.
But without a reversing valve you could put your AC unit in backwards and heat your house in the winter.
The whole premise of an AC unit is to take the heat from inside the house and put it outside, leaving you with cooler air inside.
So in the winter a heat pump simply reverses the flow of the freon and moves the heat from outside to inside. Yes. You are “cooling the whole neighborhood” when you run a heat pump.
I wish it was standard to be able to do both. My heat pump is unreal efficient and cheap and great but I’d love a cool breeze every now and then.
It definitely can. If yours can’t then it’s likely just the thermostat wired wrong.
It’s underfloor heating, the units that do both are more expensive so there must be something different.
Ah yeah that’s a different story then. However I’ve never heard of in-floor cooling before. I wonder how effective it would be since heat rises? I think you’d just have a cool floor and hot muggy air. Also the floor would condense water constantly so your floor would be slippery and if you have carpet it would be wet / damp constantly.
It’s a thing but you take really can’t cool down a lot due to the reasons you mention.
You’d need to collect the condensate, but that would actually work quite well.
WELL FUCKING OBVI-
Oh right, I forgot some people are really pulling for this fossil fuel think to pull through.
They’re only two to three times more efficient if they aren’t frozen solid. Don’t know how it works in Canada, but my mini-split heat pump can’t handle a week of 10F let alone -20 C - sure it will put out some heat, but it absolutely needs to be supplemented with my wood stove. And I live in the South. Maybe there’s some new high tech heat pumps that cost a fortune and don’t freeze over in the insane temps of the great white north? EDIT: hey, folks, how about actually responding instead of downvoting me? If I don’t have a clue, please enlighten me. Fuckers.
Your mini-split isn’t designed to function as a heat pump at low temperature.
In places like Sweden, they also use heatpumps that are designed for those conditions.
In other news, don’t drive in a Swedish winter with summer tires.
Excellent. Now I know that there are different classes of heat pump. Mine is not for prolonged crazy-low temps, others are. Thank you.
Indeed, but yours is probably cheaper and more effective at cooling when it’s hot and humid out.
For people up north, they will buy a “cold climate air source heat pump”. In temperate regions, an “air source heat pump” will suffice, while down south you will buy an “A/C with a heating mode” (also called reversible A/C).
And it’s not just about whether the coils can defrost. The whole machinery and refrigerant are different to optimize under those conditions. A cold climate heat pump has a setup that is more similar to a freezer than it is to an A/C.
Sorry about the downvotes. People need to re-learn internet etiquette.
This is the most informative answer yet. Thanks.
I have never seen so many winter tires, and studded winter tires, as I did on my trip to Sweden last winter.
I think they are mandatory there.
Theres different technology but there are some that can function to -32° F and they often have a feature that allows them to detect when theyre frozen up and defrost and then automatically switch back to heating
Mine has a defrost cycle but it doesn’t work very well. But then again, it’s use case is primarily AC - it only gets frigid temps in my area every couple years. EDIT: yes, downvote me for stating my own personal experience, asshats.
Many parts of Canada will regularly see colder than -40F, so I can sympathize easily with a view that solely relying on them might not be safe in that environment.
Tbf, most Canadians don’t live in those areas. Places like Toronto/Montreal/Vancouver rarely get that cold.
Edmonton Saskatoon Regina Winnipeg
As a Canadian who doesn’t live in the GTA it drives me nuts when people dismiss the rest of Canada as some kind of statistical outlier undeserving of acknowledgement.
Which would account for 5-10% of the Canadian population. Just the three metros I mentioned would account for 35% of Canadians. The record low for the coldest of those cities (Montreal) is -36F, but the average low in January is 7F.
70% of Canadians live south of the 49th parallel (the northernmost point of the Continental US) and 90% of Canadians live within 100 miles of the US border.
Why is it such a controversial thought to merely include and acknowledge the rest of Canada, rather than discounting them outright?
In case you’re wondering here the divide comes from: it’s this, and it’s you.
All Canadians matter, every Canadian experience is valid, and no Canadian is any less of a Canadian than any other. Erasure of Canadian experience outside of the GTA is an elitist and divisive attitude and serves ONLY to create friction where there need be none.
As soon as you erase a group from the whole, it’s INEVITABLE that they’ll seek to find their own independent identity. Considering your proximity to Quebec this shouldn’t be a foreign concept. Just feel free to extend the inclusive attitude west as well as east. It costs nothing to be inclusive of your fellow countrymen.
Because your comment suggests that heat pumps can’t work in Canada. It’s like an American dismissing heat pumps because Alaska is part of the US. For at least 70% (if not more like 90%) of Canadians, heat pumps work just fine. Obviously, if you are in the part of Canada that gets consistently below -40 degrees, don’t get a heat pump.
Also, I’m not from Toronto or Canadian so I’m not sure all that talk about elitism applies to me. I’m from a small city in the US where I experience weather similar to most Canadians.
Yes, there are cold weather heat pumps that can thaw the coils to keep operating. There is a point where they just can’t continue to operate.
When I design a heat pump system in cold climates, I always include a secondary hear source that kicks in if the heat pump gets overwhelmed. Might be a gas section in a furnace. Might be an electric heater in a fan coil. Might be electric baseboards or wall heaters.
Yes, most installations do require a backup heat source in the event outside temperature is too low for optimal heat pump usage. On my ecobee thermostat, you can set what this temperature threshold is (i.e. 20F) and then if the outside temperature falls below this value, the heat pump is stopped and the natural gas in my case kicks in. Granted, this doesn’t happen often where I live, but for those few weeks in the winter, it is not something I even have to think about. And the rest of the time, I am saving money using the heat pump and not natural gas.
I doubt there can ever be high tech heat pumps which can operate at -25 C or less, because there’s so little heat energy outside and the heat pump would probably spend a majority of the time running in reverse to dethaw the unit to prevent it freezing over.
I doubt there can ever be high tech heat pumps which can operate at -25 C or less, because there’s so little heat energy outside and the heat pump would probably spend a majority of the time running in reverse to dethaw the unit to prevent it freezing over.
It could probably be done, but then it wouldn’t operate at higher temperatures. Realistically you’d probably need two heat pumps, a low temperature pump and a high temperature pump and switch between them as the temperature rises or falls. It’s double the cost and double the points of failure, and for a situation that rarely happens probably not worth it.
I’d have to imagine at some point, more heat is leaving the house than entering, and given enough time, inside and outside will eventually reach a cold equilibrium.
Would depend on how well insulated it is, but yeah since homes aren’t exactly built to be air tight there’s realistically an upper limit to the temperature delta you’re going to be able to achieve. Ultimately the question isn’t how hot/cold is the inside/outside of the house, but how big a difference are you looking at between those two.
Your mini split probably doesn’t have a defrost function. This would all be specified in the users manual.
Oh it does, it’s just that it the defrost cycle in 15F gets off just enough ice for it to barely work, and this was when it was brand-new and verified to be working properly. I now understand that it is just not designed for ultra-cold weather, and that some are better suited for such demands.
That does kind of imply it could need a recharge. These cheaper units don’t actually have active monitoring for ice buildup - they just do it on a schedule based on temperature (and sometimes humidity). If you are getting ice buildup, it’s either outside the rated performance envelope, or it is not functioning as intended.
I think this really highlights the crux of the issue, which is just that the “tribal knowledge” of how to operate the equipment isn’t there and it’s something that education would probably help.
Like, many people’s fathers have probably shown them how to relight the pilot lights on their furnaces and hot water heaters. And if not, the “handy person” on your block would know.
Understanding how to own and operate heat pumps effectively might not be as second nature.
Understanding how to validate the extreme weather functionality of your heating system is super important. Knowing the difference between “normal” and “something is fucked up”… especially before an extreme weather event is pretty important. I’m pretty handy, but absolutely nobody in my area runs heat pumps residentially…
… but that’s probably just because of a lack of uptake rather than a real economic reason. Solar is exploding in my area as a result of increasing power costs and a great environment for it.
As it’s adopted and as people learn how to use, maintain and troubleshoot them I expect problems like that will become more sparse.
Man they pitchfork mob came out in full force for this one. I also live in the south and during the freeze of 2021 it was a struggle for it to deal with those low temps.
That’s precisely the freeze that led me to experience the inability of my Senville mini-split heat pump to keep up. So glad I had a wood stove. Even then, my shower drain trap froze solid. I was living in an “insulated” yurt at the time - good floor insulation, and somewhat okay wall/ceiling insualtion.
My attic insulation needs work. I swear I’m gonna get that sorted this year now that the heat has (hopefully) calmed down.
We probably live in the same neighborhood or something. NC here.
Nope. hollars from tx
Oh Jesus. I’m sorry on so many levels. Unless you’re gung ho Texan. Then I don’t know what to say except enjoy watering your foundation.
create energy
Ummm… that’s not how it works.
They actually added a correction at the end for that
I don’t know that we really needed a study for this. You can find the COP vs temp vs capacity curves for every heat pump out there. This will tell you exactly how many BTUs of heat the pump will produce given a watt of electricity input. I guess they were just validating that the curves were accurate?
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People think that’s a killer argument against heat pumps when it absolutely isn’t.
In that sort of climate you get a hybrid system or just leave your old furnace in as backup. You’ll use the furnace for the couple of days/weeks when it is below -25c/-13f and use the heat pump for the 6 months around that time window and save huge amounts of energy because you only use the heat pump when it’s most efficient. A hybrid system will improve efficiency because it combines the technologies at transition temps while just keeping the old furnace as backup is obviously much cheaper, since you can also get a smaller unit than you normally would because you don’t have to worry about the coldest period.
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Okay, I suppose you wouldn’t do that when replacing and old furnace but rather go for a hybrid system. In Europe loads of people are reacting to hiked gas prices and have perfectly fine furnaces in place that they don’t want to get rid of.
You might not be totally out of luck:
- More modern units do pretty well down to -20f.
- Ground-source systems don’t care about air temps (but are more expensive)
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Yowsa! That’s cold.
That said, ground-source systems have been used to good effect in climates like that! But, of course, do what’s right for you 🙂
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Which is the absolute minority on that regard, most people live in climates where it doesn’t get that cold.
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1.25% of population. The minority point stands
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Really? Where in the US or Canada do tens of millions if people live with AVERAGE winter lows of -25F?
Fairbanks AK seems to be widely regarded as the coldest US city, and that is -15F average lows. If I move to Prudhoe Bay on the northern coast of Alaska, then in find the -25F low I’m looking for. 
A quick search suggests Winnipeg is the coldest major city in Canada, and it doesn’t quite reach -20F average. There are of course some more remote towns that get colder; Canada goes pretty far north.
How cold? Also heat pumps can have auxiliary electric heat strips, maybe even auxiliary natural gas.
Not in January in Central New Hampshire.
A/C guy who’s the son of an A/C guy here. Heat pumps lose efficiency the colder it gets. I wouldn’t bother with one if you’re in a northern climate. Lower midwest, you might be able to save money with a heat pump over natural gas, but it will depend heavily on the cost of the respective energy. For me, in the central US, we have great prices on gas and somewhat crappy prices on electricity (vs most surrounding regions) and it’s definitely cheaper for me to stick with gas heat.
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This is the correct take for a conventional heat pump. However, there are relatively new geothermal heat pumps that can heat down to -30°C (-22°F) and are much more efficient.
But its all irrelevant because the most effective way to keep warm is to continue with global warming. Soon we wont have a cold season to worry about. 😜
My father in law went to a heat pump instead of propane this year. No natural gas where he lives.
But he also dropped 20k on a solar system to power it.
How long would the return on cost savings take for it to pay itself off?
If you’re on propane, it’s more likely to be cheaper. Particularly over the course of an entire heating season, because they’re more efficient in fall and spring than the coldest part of winter.
But yeah, this study wasn’t looking at cost per therm but just raw COP, which is a pointless metric. It doesn’t even compare the number of watts of heat from burning natural gas in a furnace vs in a modern power plant that supplies a heat pump. Although since we don’t have a carbon tax, that’s only a theoretically interesting comparison.
Heat pumps work fine for most people in the north. Mitsubishi’s cold climate heat pumps supply 85% of their rated heat at -13F. Buffalo is a city known for its winters, and the last time Buffalo’s lowest temperature was below that was 1982. They’re just going to be a more expensive option for most people right now.
Ditto. At least with gas I’m not paying Alabama Power’s rates.
If you posted that earlier today you would have gotten a spanking for saying anything critical about heat pumps. Or people just don’t like me in particular. Hard to tell.
That’s great, but fossil fuels are often available in the event of a power outage, and that can save lives during a winter storm. Availability is just as important as efficiency, and until we can make our power grid more resilient, we need to factor that in.
We’re also going to run out of oil in the next 40-45 years, so we should factor that in.
The 2 times (living not with my parents anymore) I had now electric power unplanned was of course when it was cold. However the fancy central heating running on gas was also not working. As the main unit also needed electric power.
So I could still cook my food but that’s was it. No heat. But that being said in my entire life we lost power (including as a kid) maybe 5 times and only for a couple of hours. In 33 years
I now have a heat pump and for cooking induction. So in a power outage I need to grab some camping gear. But I will probably survive for a couple of hours without heat.
But if you have regular power outages you and everybody in your country should probably vote and make your voices heard. If you live in a country where most people can afford heat pumps, the government can afford fixing the power grid.
I have a duel fuel system (heat pump + gas furnace) which, while more expensive, is really the best of both worlds.
In a power outage I can plug in a generator and get the furnace running.
If temps drop too low and the heat pump is struggling I can switch to the furnace.
I can choose which to run based on current energy costs.
When looking into heat pumps everyone told me they don’t work well in the northeast or they would be more expensive to run here. I found it really difficult to get an accurate estimate of the cost difference between running a heat pump vs a gas furnace. Ultimately I decided to go dual fuel for flexibility but after comparing my bills before and after I almost wish I’d gone with a hyper heat unit so it could run at lower outdoor temps because the heat pump has turned out to be cheaper but I can’t run it at low temps.
I think HVAC techs in this area are weary of them based on past experience with older units but they really have improved in recent years.
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I wonder who the fuck is downvoting these comments. LOL - “NO FOSSIL FUELS, YOU MUST DIE IN A POWER OUTAGE!”
