Insufficient cooling . Condensing uint , consisting of an Carlyle 06DA compressor and glycol cooled condensor with two cylinder unloaders and hot gas bypass, located in basement of 8 floor building . Serving two stage evaporator same floor . Three years old . The condensor has no gauges or thermometers , has a pump supplying the condenser ( a small Armstrong pump) . R-407C .
So disconnected unloaders and hot gas , both stages calling , return air 74 deg . Liquid line flashing , low suction pressure , 45 psig , 225 high side . Low refrigerant charge , right ?
Leak checked , right unloader stem leaking , everything else looked great . Isolated compressor ,replaced stem , evacuated compressor . Added 12 lbs of 407C . Head pressure increased to 285 psig , saturated liquid line and hot . Opened water cooling valve ALLL THE WAY with little effect . Delta T across condenser , maybe 5 deg f ?? System occasionaly cutting out on high head but did not catch cut out .
The system rejects its heat through a dry cooler that supplies heat pumps in the building . Increased the speed of vfd pump at dry cooler to 100 % . Bypass valve fully open , no diversion of fluid to dry cooler . Glycol temp 75 deg supply temp to condensor . Still head pressure would not drop . The load to the evaporator is low at approx 72 deg return air . \
Any ideas as to why my head pressur is so high ?? My delta t seams low accross the condensor , compressor is fully loaded my liquid line is still satureated and hot . I dont want to add any more refrigerant . Did not check for air in system , ran out of time Friday afternoon .