After finishing assembly of the full scale prototype this morning I started the heat pump running so I could measure the performance. I filled both tanks with 100 gallons of water and plugged in the compressor. After letting it run all day I came up with the following data:
Time run: 9 1/2 hours
Volume of water in each tank: 378 Liters
Cold Tank: No temperature Change
Hot Tank: 4 degrees Celsius increase
Electricity Used: 3.8 Kilowatt hours
From this information the amount of energy added to the hot tank can be calculated:
E = cp dt m
E = (4.2 kJ/kgoC) (4 oC) (378 liter) (1 kg/liter)
E = 6350 kJ => 1.76 kWh
So here is what I concluded from this test:
It appears that the cold water tank is being warmed from the basement floor. (very good result!)
The heat pump is running at only 50% efficiency (not very good :()
Since the small scale test showed a 500% efficiency with the same equipment, I assume there is a problem with the new refrigerant I put in the system after I lengthened the copper pipes. I didn’t notice any leaks in the soldered copper joints and the hot and cold pipes seemed to be in the right temperature range. I suspect that using methods based on YouTube videos might not have been the best idea.
My next step is to find an actual HVAC person to charge up the heat pump and run the test again. If all goes well this will result in a 10x efficiency improvement.