[Pegasus]

Hello to all,

After many setbacks I finally made it to built my "proof of concept" GSHP.
My main concern was the output of the GS HX Loop (~ 500m of pipe, divided in 6 circuits and buried at ~ 2m depth under the house foundation). The main consept was to test the Ground Loop with the least amount of money, while getting in to the nuts and bolts of a GSHP.

The contraption is consisted by :
- Compressor : R22 2,9KW - 0.85 Ton from an old A/C (COP 3.5)
- Condenser : The A/C condenser coil submerged into a barrel where the Ground Loop water circulates (I can get a proper plate HX costs about 300 Euros)
- Metering Device : R22 Danfos adjustable TXV that can handle the compressor cooling capacity.
- Evaporator : 2 x plate HX ( I used both because they are small. Wrong e-bay order)
- Refrigerant : Initially R-22 then R-290
- Extras : LP+HP Safety switch, Refrigerant HX, Filter - Dryer (for R-407)

All welded together with awful craftsmanship (unlike randen) and put to the test.

During my GSHP study period I have found a very helpful book for beginners in the HVAC world like me (attached in the post). It is written for fridge truckers in plain English. It also has a very easy troubleshooting guide that the most experienced of you could quantify for R-290 GSHPs, check it out.

I am writing this because my main problem is that I can't lower SH below 6 deg C so that to use all of the Evaporator capacity. From the above troubleshooter my case is (most likely) the liquid line restriction and my best guess is the small orifice that I chose since I didn't took under consideration the increased COP.

As far as the Ground Loop, I believe it can handle a bigger compressor since the return temp is only 2 deg above the no load temp (25 --> 27) so it is a go for a proper set-up.

Any comments would be helpful.

P.S. There is a very nice "Refrigerant Slider" free app from Danfos that includes R-290!