I am about to pour a concrete floor in an addition to my basement (about 13' x 24'). This room is adjacent to my electric water heater. I have bought a 9500 btu R-22 compressor which I plan to use to replace the electric element in my 50 gallon water heater. The condenser is the water heater tank where I have shoved about 50 feet of 3/8" copper tubing inside. The evaporator will be 3/8" copper tubing buried in the concrete floor. Has anyone tried this before? How much tubing is enough for proper heat transfer? How should I circuit the tubing? Once the concrete is poured, my design will be "set in stone"!