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Do you have a Heat Pump in a cold climate?

Looking to get some anecdotal experiences from someone living in a cold climate using a heat pump as their main source of heat.

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  • The main thing with heat pumps is that they obviously do heating and cooling. For most other systems, those two functions are separate, and can be sized appropriately.

    If you live in a climate that is mostly hot, with some cold days, you'd size to accommodate the hottest days. If you live in a cool/cold climate, where you'd only occasionally need cooling, you'd size for the coldest days. Going oversize is bad because it is inefficient and just doesn't work as well. It is often better to size the system to accommodate 99% (or whatever %) of days, and have a little backup heat and/or cooling capability for when the pump can't keep up than it is to oversize and run inefficiently most days.

    I lived in an apartment with a heatpump sized to handle the cold, and it kept me warm always with no trouble. It wasn't that cold of an environment, though. During the summer, it would kick on to cool the place, and it would cool very fast. That sounds good, but what happened is the temperature would be fine, but the humidity would be very high, and I would get condensation on my windows and mildew in my closets. I ended up having to increase the hysteresis of the system, so instead of letting the temperature rise a couple degrees above the set point and cooling a couple degrees below the set point, it had to swing much further. That made the system run long enough in one shot to decrease the humidity, but it basically made it so I'd have to either let the place get uncomfortably hot first, or cool it down to uncomfortably cool.

    If the system were smaller, maybe there would be a few days a year where I would have to wear a sweater inside, but I wouldn't have to worry about 150 days of too much humidity.

    The last thing to think about is air-source vs ground-source. Air source is basically a drop in for an air conditioner, but has a lower limit on temperature it will operate. That limit has gotten a lot lower over the years, but AFAIK, there are theoretical limits it can't beat, depending on the physics of the system and particular refrigerant. Ground source, aka geothermal, should work most places provided you have the space for it, and money to install it. Underground never gets cold enough that the physics of heat pumps aren't effective.

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