Ingersoll Rand won't restart in a two compressor setup

by Eric
(Orange, CA)

We have an Ingersoll Rand UP6-15-125 that we want to use as a back up to our 20 hp compressor.

The 20 hp is set to kick on at 110psi and cut out at 135.

The UP6 is set to go on at 100psi and kick off at 125.

The UP6 works fine when it is running alone but when it runs in tandem with the 20hp compressor it won't kick back on at 100psi.

The only difference that I see is that the 20 hp is going up to 135psi. I am wondering is their some sort of override on the UP6 that is being thrown over 125psi and if so can we adjust it higher?

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Bill says...

When you are running the compressors in tandem, the UP6 is set to cut in when the 20 HP can't keep up with air demand, right?

Air pressure in your system falls past the 110 PSI cut in for the 20 HP, it starts and is running, but the pressure is still falling to the cut in point of the UP6 due to demand, is that correct?

Tell me, do you have a check valve on the outflow of either compressor before the lines tee up?

If you don't the pressure from the 20 HP may be flowing back down the line to the UP6 and preventing it from starting.

Cheers,

Bill