Searching the web only gives a few clues. Anybody have practical experience or product/design examples??

Obviously during the summer you can get some free heat and more efficient cooling, at the cost of a small circulation pump running water to heat exchange medium connected with the condenser tubing – my thought is a braised plate seems most logical.

But then come winter, the mini-split flow is reversed which would mean some plumbing issues, and the exchanger would be first inline before the mini-split duct which would siphon off heat, an issue when things got much colder. I would need a way to bypass this during the freezing winter months.

It seems fairly cost effective. Small run of water pipe in crawl space, small pump, a little brains/thermostats, some fittings.

A couple packaged products seemed awfully expensive for what little they offered.
Also have to keep in mind refrigerant oil, ie the exchanger can’t cause the tubing to dip

Heat pump model being installed is the Fuj
cheers