AC_Hacker I will approach this with some caution. The ground loop now is a mixture of propylene glycol and water protecting from freezing down to -15 Deg C. But if my loop approaches 2 Deg C I'm going to stop the system I don't what to freeze the ground around the loop tubes. I've heard some stories about making permafrost. And airconditioning in the summmer is not the cure.

Randen

Randon, I would not be too concerned about the 2C mark. Since the glycol is good to -15C, you will not harm the system going down farther than 2C. Also, you will have a VFD so you can run it at 80% if you like just to keep it closer to the original design. Keep the pumps running regardless.

Randon, how did you filter the propane? I was thinking that there might be non condensables that are keeping your performance down.

Vlad had the definitive cure for that. Just pull it out of the bottle as a liquid. If they can't condense, they can't leave.

Yes, but you can get water with your liquid propane and there is varying amounts depending on supplier. Am I missing something here?

Well we have another GSHP running. The Varible Frequency Drive (VFD) is sooo smooth with the way the motor ramps on start-up. Of coarse you can control the presure with the speed. The scroll compressor is soo quiet. It is just running on the bench with no heat exchanging fluids so temps and pressures went crazy after 1 min.
I had programmed in a ramp to 3450 RPM in 5 sec and a ramp down to 0 RPM in 10 sec. If the motor becomes overloaded it will shut down. As the motor is starting you can watch the LED read-out with the current voltage RPM as they change. You can set a fault to wait on re-start. There are so many great capibilities with the VFD. It has low voltage input for the thermostat control. I may have to wait till the weekend to install the GSHP with the loop connections.

Randen

No, you're not. I am. I forget you guys get really dirty gas. Ours is about as clean as clean.

Having said that, pulling liquid and then feeding it through a couple of filter/driers would take care of that. The molecular sieves used in those will grab the water pronto.

I hope there is a high pressure switch in the loop somewhere set for maybe 325psi (as well as low pressure that can double for loss of refrigerant). You don't want to rely on the the pot for high limits.

I don't think ours is that much dirtier than yours but the mixture is different. Warmer countries have more butane than we would. We all have some moisture in propane or there would be no use for condensing boilers.

Congratulations!!

Is there some kind of computer control interface to the VFD?

-AC