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Norway is among the countries with the most heat pumps per capita, along with neighbouring Finland and Sweden
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- Title
- Nordic countries debunk 'false myths' about heat pumps in the cold
- Published
- Oct 30 2023
- Word count
- 793 words
For those of you in the US, what's a good heat pump for a mild-ish climate such as Virginia?
With the exception of one studio apartment, I have never lived anywhere with a heat pump that actually heated the house as well as radiators. Yes, I've made sure the house is properly insulated, doors and windows were properly installed, but nothing, and I really mean nothing heats as well as radiators.
It is 45 degrees F here right now in my part of the statw(7° C), I've got multiple layers on, slippers on my feet, hat on my head, and it's still cold in this house even though the thermostat reads 74°. The heat pump is some sort of a Trane heat pump that's only a little more than two years old.
What am I doing wrong?
As a heat pump advocate* I have two thoughts:
While I agree that a heat pump heating air forced out of registers or ceiling vents won't be as warm as the hot air rising via convection off of a radiator, the name of the game with a heat pump is efficiency per thermal unit rather than intensity of heat. So while your radiator will likely heat better, you're using more energy - spending more money - to do so. This might not be true in all cases, for example in locations where district steam heating is used because that can be quite low-cost; however, if your radiators are closed-loop water radiators in your home, you have to heat that water somehow. In my experience this is generally by burning oil and gas. Because your heat pump is pulling "waste heat" from the atmosphere outside, concentrating it, and then pushing it inside, at 45 degrees it won't be an intense heat and your heat pump will run a lot longer to do so - which is actually what its been designed to do, because in fact short cycling is bad for heat pumps. So if you run this thing and it takes a while to heat your home from a cooler temp, or runs longer when it's colder out, that's all by design and isn't anything to worry about. In fact when it gets cold enough out, your heat pump might run darn near continuously... somewhere a little before that point is when it's time to make sure your HVAC system appropriately engages its auxiliary or supplementary heating unit.
For a definitive answer on your system, I'd first use a secondary thermometer that you know is accurate to make sure that the thermostat's 74 is an actual 74. If it is, the second question I have is whether air is circulating in your home - because hot air rises, it can sometimes get trapped in a layer of warmer air at the ceiling. This is especially the case in older homes with high ceilings, arched ceilings, tray-style ceilings, large open-concept rooms, etc. If you have ceiling fans, run them backwards so that the blades suck air up towards the ceiling. This will forcibly establish a sort of convection cell in the room, pushing the hot air off the ceiling and down the walls to you nearer the floor (and coincidentally, this is another reason why radiators work so well - they use convection to their advantage). If you don't have ceiling fans in particular rooms, you can do the same with a box fan angled to blow upwards on its lowest setting - too much air circulation will make you feel colder, so gentle air mixing is the way to go.
If after all that you're still not satisfied, call a local and reputable HVAC company for an evaluation. Sometimes they're free, sometimes they're a nominal flat fee, and they're usually called a "preventive maintenance checkup" or something like that. They will make sure your unit isn't malfunctioning in some way - it's leaking charge, your refrigerant system isn't plugged, your compressors and reversing valves are all working, etc. Anyway, hope that helps, let us know if you get something working! Because you shouldn't be cold with a functioning heat pump at 45 degrees F, a modern system should perform well.
*I have two HVAC heat pumps, one primary system for the first floor of my brick rancher, and a mini-split heat pump for my basement. I also have one of those new heat pump water heaters, and it's freaking awesome.
Shot in the dark here as this has been the case for me. The vent register was very close to the thermostat and would trip the thermostat off frequently, leaving most of the house cold.
They're going to have to convince me that they actually work in a COLD country.
Average temps in Norway in February: -2c to -7c. Average temp where I live in Canada in February: -5c to -17c. Our low from last winter was -47c in Dec.
I don't think I'd trust a heat pump to actually heat a house at those temps. The few I've seen are slow to heat or cool and when the door opens at -40c you want heat and you need it fast.
It's not something you can rely 100% for 365 days of the year, since most air-source pumps stop working around -15C to -20C. That's why we have backup heating for those cases. We're relying on the fact that the extreme cold snaps (-20 or colder) last for days at most so the backup can handle the spikes.
The actual heat is distributed by circulating water in radiators around the house (or in-floor), so it's pretty easy to add additional ways of warming the water. There are even solutions where you can direct the heat through the mass of a fireplace. Others use wood, wood pellets, oil, direct heat or whatever as the backup.
For true cold weather management you'd want a ground-source heat pump, which is a ton more expensive, but the running costs are a lot lower, it's just a water pump.
If you wanted to rely just on the heat pump for all your heating, you would probably want a ground-source heat pump, rather than the more typical air-source heat pump. Air-source heat pumps can really struggle in the extreme cold (under -30° for the newer cold-climate heat pumps that are coming out now; older, warm-climate air pumps will struggle at -10°C).
To save money, people who live on a climate margin (i.e., they see a few nights below -10°C in a warmer climate or below -30°C in a colder climate, but it's not the norm) will usually get the cheaper heat pump, and then supplement with a more expensive secondary heat source as needed. But if you see a lot of these colder nights, getting a colder-rated heat pump will probably be more economical, depending on how expensive your secondary heating option is to run.
That's what I mean. The logic escapes me. So you can buy a more expensive heating system that doesnt actually work well when its really cold (which is kind of the point of having a heating system isnt it?) unless its supplemented by another heating system. More money up front. More complicated and more systems to maintain.
OR
you could just buy a cheaper system that actually works in mild OR harshly cold weather and only have one system to maintain.
I mean, its lovely to want to make changes to 'save the earth' and all, but in all practicality MOST people are happy just to be be able to pay their bills. They're not looking to replace what works well with something that's more complicated and more expensive to do the same thing.
And as for ground-source heat, dont even get me started - I looked into it a few years ago and the cost STARTED at about 20,000 with averages at around 30,000 here whereas a furnace could be bought for 4000.
I think this is a cost disparity thing again. In the US natural gas and oil are dirt-cheap. Electricity is expensive.
On this side of the big ocean it's the other way around. A high-COP heat pump will beat pretty much every other heating system 95-99% of the time cost-wise, even if you factor in the installation costs.
For reference, heating oil costs 1.6€/litre over here ($6.4/gallon in imperial). Electricity on the other hand is around 5-10c/kWh and dips to literally below zero when there's ample renewable production.
Ground-source break-even is usually measured in decades, but after that it's essentially free heat/cooling.
(EDIT: Fixed €/l -> $/gallon conversion)
Ah, that makes sense. Here in Canada, specifically Alberta our electricity has gone sky high. The actual cost per kWh is reasonable at .096/kW but then they add on admin fees, distribution fees, fixed charges, distribution and supplier charges, plus two taxes and by the time I get my bill the $90 in actual kWh usage is now a $230 bill.
But you're right, I can fill my 1000 gallon propane tank for about $1000 and that will last about a year. This year we're using our wood stove pretty much 24/7 so I anticipate our entire year's propane bill to be about $100.
I think you added an extra decimal place in your conversion. Would be closer to $6 if a gallon is 3.79L, no?
Totally agree with the rest of your points, though. We need more heat pumps everywhere, but some places don’t have a good incentive structure in place yet, unfortunately.
But if you don't get harshly cold weather, there's nearly no downside. Heat pumps are far more efficient than other options when it doesn't get too cold for them to work properly, so if your climate generally stays above that temperature you're almost definitely going to save money on heating. Plus, heat pumps can also give you air conditioning basically for free -- something that is definitely relevant for european buildings that usually don't already have other air conditioning with Europe's rising summer temperatures.
The AC bit of heat pumps is becoming essential even in Finland, we used to have maybe a week's worth of days every summer when it was uncomfortably hot to be inside during the summer.
Now it's well over a month. Having an AC is the difference between sleeping comfortably and not sleeping at all. Our buildings are built to RETAIN heat, which is awesome in the winter ... notsomuch when it's +30C outside.
yeah I live in Germany and I'm suffering over the summers here. But Germans will almost certainly be hella slow to update something like this...
I've installed a closed loop geothermal heat pump to replace my propane furnace and central air. Best choice I've ever made.