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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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Makes sense. Heat pumps are one of the few heating systems that can achieve greater than 100% efficiency. (energy in vs total heat output)
As long as you can keep the evaporator above the evaporation temperature of your compressed refrigerant, you're golden. Burried lines are excellent for that in colder climates, but the space for it isn't always easy to find.
It's a little more expensive, but most places can find the space by drilling straight down. Still worth it from what I've seen in most places.
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.
The Guardian is a UK publication.
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.
That was obviously a typo, you concern-trolling asshat. Your FUD tactics are the flavour du jour with the fossil fuel lobby and are easily demonstrated to be nonsense by real-world examples.
"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.
It can go down to -30C (-22f) sometimes or even below that
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
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
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.
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.
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.
I mean, in the colder climates that have natural gas piped to homes anyway.
Why not use a pilot light worth of gas to keep the evap side a tad bit warmer on the days that it drops real cold.
Sure, your still using some gas, but you'll be extreme sipping at it.
I'd rather go full electric and get rid of the gas infrastructure entirely tbh. Take that cost and put it towards local power generation+storage.
Heat pumps most of the time and radiant electric heat for the few times the heat pump won't quite cut it. Geothermal if that's an option in your location.
the upfront cost for something like geothermal is still outrageous, though. anecdotally, i bought my house with an older unit that ended up catastrophically failing after the reversing valve got stuck and destroyed the compressor. only 1 local shop in the area serviced the thing (same people who installed it when the house was built...) and the unit had long been discontinued since the company that made it (hydro delta) went bankrupt years ago. it was over $15k to put in a new updated unit... luckily my home owners insurance (with the help of a rider i added a year earlier that covered home systems) footed the bill, albeit after a long and arduous battle with the 3rd party shits that state farm outsourced it to. now this new system has a 10 year warranty on parts and labor, otherwise, i would have switched to gas in a heart beat. i can put in a new gas unit every year for 10 years at the same price... so while the geo's monthly electric bill is nice, i wouldn't dare install a new residential build with geo... plus add another easy $50k for the loop field if it's a new install.
i'm afraid what's going to happen once then 10 years are up since that always seems to be about the time major home appliances fail... probably try to move by then so it isn't my problem, lol.
Counterpoint: electrifying homes is also a huge cost savings in general once you are at the point where you're willing to forgo that big gas furnace in favor of an efficient heat pump system.
Cookers use very little gas. It's really only water heaters and furnaces that use a lot of it, and heat pump units are incredibly efficient for both those tasks. Though I will admit that the noise a heat pump water heater makes is just atrocious and you'll need to figure out if your can manage that in your life (e.g., by setting it to only run at night, when you're out of the house, or putting it somewhere far away from where you spend time).
Keeping a gas hookup at $15+/month for a single appliance like a water heater or range is an expense a lot of people can and should trim, but instead they treat it like a sunk cost and think "well I have this one appliance, so I may as well get MORE gas appliances". Which is intended. The whole "now you're cooking with gas" campaign and all the nonsense ad campaigns about how gas ranges cook better than electric* was a deliberate (astroturf) marketing campaign from natural gas utilities because they knew that keeping electric cookers in the house would stop people from abandoning the appliances that ACTUALLY use gas but were hard to get people passionate about. This isn't a conspiracy theory; we have the memos and POs.
* the difference is at best unnoticeable to the average cook and I truly believe the performance is worse, especially when factoring in time spent cleaning. Electric ovens are flatly better and modern electric cook tops work super well, even if not induction.
Gas is great if you need to boil a pot of water right now. Like in a restaurant kitchen.
Any application that is not in a massive rush is just fine on electric.
Even modern radiant electric boils water faster (pretty typical for even a pretty low-end electric top to have a 3500-5000W quick boil burner). And induction or a kettle both do it a near order of magnitude faster. Not to mention none of them hugely heat up the room or require a superpower ventilator that sucks out your conditioned air. If boiling water fast is the task you care about, gas is almost certainly the worst choice. At least for home use.
Commercial kitchens are a different story that isn't even part of the discussion. Even with three-phase power, to run an all-electric mid size-large commercial kitchen would likely require some crazy service level that wouldn't be available in many places. It'll be a while before that is an option.
Well technically electric ranges are worse, but other than that you're right.
Even then induction is faster and cooks more even, maybe restaurants need open flame, but yeah I don't think anyone at home needs gas anymore. If you don't care how you cook you can go electric. If you really care in many ways induction is better than gas.
Really, the only thing you can't do on an electric range that you can do on a typical gas cooker is, for example, directly fire a pepper.
And you really don't need to do that. You can just do it under the broiler, for example. I also don't even insist on induction. A mid-range radiant top is STILL better than gas, in my opinion, though the induction is worth it if you can afford it.
People will bring up woks a lot, but a gas range also can't draw out the real advantages of a wok and you're better off with an outdoor chimney cooker or a dedicated wok burner (induction with a small torch or gas bottle) if that's what you really care about.
Plus, I must again point out how fucking AWFUL it is to clean a gas cooktop compared to how trivially easy it is to clean a glass-top electric cooker. The time saved cleaning more than makes up for the advantages people list with gas even if we grant those advantages exist. Which I clearly don't.
many people just have a lil' torch for when they need flame, presumably vastly more efficient than turning on an entire burner just to scorch a chili
They don't; not from gas. The obscene heat it generates in the kitchen alone is horrible for everyone working there.
Induction is much, much faster.
I haven't seen this argument listed yet, but my reason for wanting to go off natural gas is how much we lose in transmission. I don't feel like finding sources right at this moment but most estimates I've seen are ~2%, and methane is a pretty potent greenhouse gas.
Methane is one of the cleanest burning fuels there is. There should be more effort put into fixing the distribution leaks rather than trying to switch everything to electric.
Fossil methane is still fossil. Ie. not part of the CO2 cycle, and thus contributing to the greenhouse effect. Methane itself is 20 times more potent, and we should do everything we can to limit methane emissions, both fossil and natural.
Agriculture is a big source of natural methane emissions, and even fairly small dietary changes can significantly reduce livestock emissions, but don’t see anyone doing that either.
Highly suspect small gas line leaks won’t be fixed either.
That is a rather big ask and maybe that effort would be better directed elsewhere.
Also, think of it this way. Isn't it a bit crazy we send lines of pressurized, explosive gas directly to most homes in North America? If we do need to keep burning natural gas, we can do that in power plants and get about the same, if not better efficiency by using this electrical generation with heat pumps.
You're better off heating the inside of the house with gas that heating the outside of the house with gas and using the heat pump to transfer that heat into the house. Replacing the gas line with lines for the heat pump would be best.
Also keeping the evaporator from getting covered in ice where it doesn't work. Yeah you can defrost but in certain weather it's just going to ice up immediately.
It's literally pulling heat out of thin air (or ground).