[vwhead77]

Ok - second experiment - external coil / discharge from HP - (it's actually a lot more wraps than the internal coil) I managed to wrap 30' of 1/4" copper around a 2" copper pipe. I'm going to insert it into a 4" PVC jacket and fill it with 'fire rated' foam insulation. I'm thinking that a smaller water tube diameter with flow metered by ball valves, will actually give me a decent HX rate. I will have to transition from 2" to 3/4" and use my installed unions (previous pics) to interchange all these gizmos I'm making - (hey I'm semi-retired so I get to play with stuff).

Update : 10/30/14 - INstalled the hp water heater with the coil wrapped around the outside of a 2" pipe/insulated/ and throttled with BVs. Using R209, I have managed a 20 degree differential across the jacket at 4.5 amps. My electric 208V only gets 10 degrees at 12 /14 amps. Definitely gaining ground - my only issue now is the best placement for the outlet side. so far so good