On Monday, May 24, 2021 at 11:01:27 AM UTC-4, m kraus wrote:
i have a second detached garage with a 25'x40' x 10 ft high basement that is built into a hill. considering putting heat pump in this unheated building.
any thoughts from the experts. currently the heat pump lines run 25 ft, placing new heat pump in unattached bdlg basement would add 40 ft of line which can be well insulated.

Not sure what you intend to do. Are you intending to heat the whole garage or just
the basement? Whatever it is, heat pumps are sized to what they need to heat,
I haven't heard of adding on a whole substantial additional load to an existing system,
not sure how that would even be done. Heating a 40 x 25 above ground structure
would be a larger load than heating just the basement. Also obviously depends on
the environment, which is unknown. Seems like a separate new heat pump system
would be required and the most logical approach.