Where are you going to get your air source? I think my plan to use the basement air might be limited to under 10,000 BTU..
So, I've been thinking about using outdoor air (like a regular heatpump) and only using it on mild days..
The Airtap HWHP at
Airgenerate.com | Adaptive Energy Solutions
seems to do okay down to 32 deg, but I'm pretty sure it's going to get frosted over..
The basement air would be pretty dang cold if you installed 4 or 5 AirTap units in your basement..