Hello,
I have been trying to fine tune a refrigerated 8 gph drinking fountain to meet the ARI standard and increase efficiency. The compressor specs are
R134a
Capacity
W ±7% 843
kcal/h ±7% 725
Btu/h ±7% 2883
The Evap coil is a coil on coil tankless type and has proven it can meet the capacity requirements for ARI with 4.25 oz charge. The standard calls for 8gph at these conditions Ambient 90 water inlet 80 water outlet 50. The HS pressure is the issue 240-280 psi. I thought it could have non condensables or moisture so I revacuated for 4 hrs down to 125 microns, it held. Ran it again, no change in the pressure. Thought maybe there was restriction at the expansion point (drier cap tube type) so I changed both, reevacuated successfully, recharged, ran it and still no change in the pressure. It was suggested to cut the cap tube length 6" and try again. Went through all steps again and re ran still no change. Cut six more 6" off at the request of my boss. Still no change in pressure but the flow dropped down to 6 gph. The system temps and subcooling and superheat all seem good, but he keeps saying the pressure is to high. I can not get why it is to high out of him. Can it be the compressor is low quality and just doesn't perform like a danfoss (our standard compressor)?I am suspicious that the vacuum pump is not working as it should. Can there still be moisture in the system even after a 4 hr evac to 125 microns? Could it be the wrong oil type for the pump? Is it ok to liquid charge at the compressor service port? I am no expert and my boss is not either but thinks he knows everything which makes it pretty hard to tune this unit. Any advice would be appreciated.