Copeland Compressor Suction Unloader

[iceman007]

What would be the accepted method of setting the two suction actuated unloaders on a copeland recip compressor. Running on R407C and they seem to be cutting in and out almost every second or two, so I think the differential is set too low. I wouldn't want to flood them back either (one of the compressors is getting an oil fault intermittently)This could be the electronic oil transducer, or too many starts, but most probably because the things keep cycling off without pumping down properly.

Thanks

[RANGER1]

I think you answered your own questions in a way .
Depending on control system ( sounds like you have pressure switches ) but sometimes you can have timers to stop short cycling of unloaders .

Compessor could also be not balanced for the load you have , if its never happy .

[iceman007]

I think you answered your own questions in a way .
Depending on control system ( sounds like you have pressure switches ) but sometimes you can have timers to stop short cycling of unloaders .

Compessor could also be not balanced for the load you have , if its never happy .

Yes they have pressure switched, one for each unloader. On one of the compressors I thought I would widen the differential and get it running so it doesn't unload until it gets down to a reasonable level (just under 400) and then set it to load at 500 instead of 460 as it s now. Haven't thought about the back unloader yet.

[D.D.KORANNE]

Try out frequency drive for compressor capacity control if the comp model has an oil pump .