[chrislund]

Depending on your market, Sanden and Mitsubishi make air-source DHW heat pumps where the evaporator/heat source source is remote (i.e., outdoor) rather than integrated with the tank. I can't speak to Mitsubishi's line but IIRC Sanden has the DHW go straight to the outdoor unit, but then you may need freeze protection, which I think Sanden provides via heat trace. When my current water heater bites the dust, I plan on getting a Sanden, and looking in to the feasibility of making a glycol loop between the outdoor unit and an indoor "indirect" tank to eliminate the need for freeze protection.

[kennywinker]

Thanks for the tip! Where I am Mitsubishis seem to only be available through big-name installers, and the only thing they offered me when I talked to them was the all-in-one style that cools your basement. Living in an old house with not great insulation between floors, that was a hard no-go. I'm now googling the Sanden ones and getting some promising results I hadn't seen before.