Speculative Q: Passive solar heated (outdoor) space as air source for heat pump?
jywarren
| Posted in General Questions on
This is a very speculative question, so thanks for humoring it — for air source heat pumps which use outdoor air, would there be any advantage to enclosing the intake in a kind of greenhouse or cold frame? Greenhouses can be 10-30° warmer than ambient temperature, depending on various factors. I’m not up to the calculations of volume, kilowatts, etc — but just curious if anyone’s done something like this. You could even paint the inside black, like one of those solar timber kilns on YouTube (image attached).
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Replies
I think you'd save money for a couple minutes - but a heat pump moves a lot of air (mine up to 800 CFM), so you'd be tapped out quickly.
I agree with Paul. I could see just having the roof and maybe the front wall, and maybe use black material instead of clear, but leave the end walls open. That might raise the ambient temperature most of the time while allowing plentiful airflow. It would also keep snow and ice from accumulating, if that's an issue where you are. But it's probably best to just keep the equipment fully exposed.
If you consider the basic thermodynamic behaviour of a heat pump heating a home, putting a heatpump compressor/evaporator in a smaller enclosed space would severely limit performance after a very short time of operation.