[randen]

Ron342

I had found that there is the sweet spot (quantity of R290) in the system. As you add the refrigerant the pressure-vapour mechanism begins to function. Along with this increase in the volume of R290 the resultant current draw increases (amperes increase).

Remember your goal. Harvest the most amount of heat for the least amount of power.

Monitoring three items Current draw, Condenser temp, Evaporator return temp. I was able to have some success. It took some time to tune.

The condenser temp increase is the one we want with a low current draw and the evaporator working efficiently. Its a balancing act. You may want a little frost on the evaporator tube were the capillary tube enters. By the time this R290 enter the evaporator it is absorbing heat as it flashes from a liquid to gas. If the gas can return to the compressor at near ambient temp the refrigerant has absorbed a quantity of heat. Remember you want to heat the water not air-condition the room.

I had found the following results: (your mileage may vary)

Condenser temp from the compressor 150-160 Deg F
Evaporator temp returning to compressor 50-65 Deg.F
Current draw 2.2-2.5 amp.

For my system I had actually overcharged the thing and had to reduce the charge slowly monitoring the two temperatures and current. (tip the use of a Kill-O-watt meter is a most valuable tool) The reduction of charge was very linear to the digital display of wattage on the Kill-o-watt meter. The clamp type amp-meter jumps around a bit.

My hacked system is very simple with a capillary tube and no TXV. or filter/dryer or liquid receiver or over/under pressure switches. (compressor has built in over-temp safety switch) Wall receptcal has 15amp panel breaker. Remember some of the best machines are the simplest.

End result total run wattage via Kill-o-watt 375 watts including evaporator fan. The daily use of hot water by two retirees is about 4Kwh. I believe this is very close performance to what is expected by the Geo-Spring GE unit.

Best of luck

Randen