BAD FLOODING PROBLEM/TANDEM R-22 SEMI-HERMETIC COMP

[unguidedrookie]

JUST STARTED JOB AND RESEARCH HAS SHOWN TO HAVE ALOT OF COMPRESSOR FAILURES FOR RUNNING TO HOT /HAVE REPLACED TWO 60 HP COMP BOTH HAD CHUNKS OF METEL ON TOP OF PISTONS/I WILL NOT LET THIS BEAT ME!! NEED UNDERSTANDING OF UNIT/SET-UP ANYONE HELP?

[bku46]

Well its obvious you have a slugging problem, do you know much about superheat and subcooling, oil return and level? Thats what you need to focus on and if you get that set up maybe you wont have metal on the pistons.

[rubobornot]

Does the min. air flow match the min. capacity that the compressors can unload down to? Are the tandem compressors interlocked, by suction pressure, so that if just one needs to be running it will not just both running unloaded alot of the time. Does the pump down cycle work. are the unloaders controled by a temperature control or suction pressure. Is the evap coil clean. Is the AHU moving the right amount of CFM. Are the air filters clean. is the oil pressure switch intact and working. is the superheat being controled by the TEV. Is the blower interlocked with the condensing unit so if the blower shuts down at night the condensing unit pumps down. Do you have any access to the failed compressors, if so you could check the crankshaft for wear patterns. If it is even wear the cause is a running flood back , if the wear is uneven it could be a flooded start situation. could you add an accumulator to the suction line to prevent slugging the compressor from rapid load changes. are the crank case heaters working. If the unit has a hot gas bypass is it working and is the valve located at the condensing unit or the AHU. If the valve is at the AHU a large amout of liquid could develope in the line and be shot into the evap coil passed the TEV.
Valve should be at the condebsing unit so the line is under suction pressure till hot gas is fed into it. it should also be insulated up to the inlet of the distributor.

[airworx]

should have 10 degrees subcooling and around 20 degrees superheat. charging has two be done fully loaded.
make sure unloaders are set properly. should unload at around 58 lbs dx and 55 lbs chill water.

you are slugging compressor. generally most compressor failures are due to flooding.
what you really need to do is understand subcooling and superheat. you cannot charge or adjust txv or troubleshoot
easily without this knowledge.