[Richard]

And I hjave a slightly different opinion than Russ, but close to what he said. When the HWH system is active in level mode it sends 110V to the aux compressor that OVERRIDES the well pump switch. Newell's attempt on my coach was to install such a regulator backwards to keep the compressor from overpressuring the system.As Russ stated the attempt was to install a relief valve. It doesn't work very well, in that I blew an airbag bt leaving the system in auto. The brake gauges were pegged at 150. The specs for the Thomas compressor say it will prodcuce 150 psi and I believe it.

You could also screw the knob all the way out and see what stops working...........