I'm planning to retrofit my Juneau, Alaska house with a ground source heat pump. Heat loss calc. for the house is 32,300 BTU. Cooling isn't an issue here.
My contractor is recommending a 4 ton Econar Ultra unit (~40,000 BTU at 28F EWT; 45,700 BTU at 32F EWT).
I'm wondering whether a 3 ton unit might make more sense (~28,000 BTU at 28F EWT; 32,800 at 32F EWT)
Will be installing a new duct system, and the contractor seems familiar with designing for a GSHP system.
We've always heated with electric resistance and wood, closed off portions of house during infrequent coldest spells, usually keep the house cool (typically 65F), and intend to keep using wood as a backup and for power outages.
Additionally, while I want a desuperheater, I would expect to turn it off in coldest weather.
Also, I have no reason to think that the 28F EWT winter minimum is realistic -- it doesn't seem based on local data, and I know from 20 years of gardening that the area the ground loop will be located in (buried 6-8 feet) generally does not freeze more than a few inches and never more than a foot deep. A water seep/spring often melts snow in the area.
Cost is partially the issue of course, but so are issues of equipment wear from starting/stopping more frequently. Should this be of concern?
Should I go up to the 4 ton, or down to the 3 ton?
What other factors should I consider?
Thanks for any advice or information.