Heat pump in a Pan-abode cabin
LouLouInTheWoods
| Posted in General Questions on
I live on Vancouver Island and recently bought a pan-abode house. It has wood stoves and baseboard heaters. We are looking at options to improve efficiency. Having a new insulated roof installed but hoping to replace the baseboard heating with a heat pump.
Does anyone have experience installing a heat pump in pan-abode construction? They say cutting holes in walls can be tricky as all the logs are load bearing.
I don’t know much about ductless heat pump installation, do the units need to be installed through the wall? Or are they just mounted on the wall?
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Replies
Most mini split installs need a 2.5" hole, you'll be fine with cutting that through any of the lumber walls that is no above a door or window opening.
One item to watch is where the outdoor unit is mounted. Even with solid lumber walls, vibrations from the unit can carry through the structure and can be very noticeable inside. You generally want to mount those only to masonry or if you foundations is very low, onto a ground mount.
These types of structures can be fairly leaky and it is very hard to estimate the amount of heat it will need. If you have previous heating bills, I would run through these calculations to estimate the size:
https://www.greenbuildingadvisor.com/article/out-with-the-old-in-with-the-new
Since most of the losses in these types of buildings is air leaks, insulating the roof will help a bit, but won't change the sizing that much.
Practically there is no impediment to installing a test pump in a Panabode. While the walls are load-bearing, because they are laid horizontally the logs also become lintels if you leave a couple of courses, which y0u can see at the windows and doors.
As Akos said: They leak air like sieves. During renovations I've had sheets of poly I put up for dust control blow back and forth as though a door was open whenever the wind picked up outside, and wood burning appliances often backdraft. It significantly affects het loss and there isn't much you can do about it unless you want to clad either the inside or outside of the Panabode (which sort of defeats the point of buying one). The problem with the poor air-sealing is it makes predicting heat-loss difficult, and coupled with the very low R-value of the walls means they require much more energy to stay warm than a conventional structures of the same size. The heat pump will have to be oversized to keep up in cold, windy weather.
Thank you both for the helpful reply's!