Cannot recall which thread I was going to put this in, so will post as a general thread.
Rather than a coil, my 5 T water to R22 (or R290) evaporator is simply tying a bunch of coaxial pipe together.
Pic or HE attached to ceiling of basement, with proper slope for refrigerant oil.
Also pic of assembly with spiral 1/4 tube (or even poly rope would work) to get better heat transfer. Note the inner 3/4 Cu tube was radially sanded with 36 grit to further increase turbulence and hence enhance het transfer.
Transition to outer water jacket by simple expedient of casting epoxy seal in side old green bean or OJ cans.