The on/off switch on the compressor must also be an unloader valve. You could add an NORMALLY OPEN solenoid valve to bleed of the air pressure between the compressor output and the connection to the reservoir when the power is removed. There needs do be a non return valve on the inlet to the reservoir for this to work. I think there must be an air pipe connected to the on/off switch for the original system to work. A diagram of the piping which shows the location of the pressure switch and any valves on the compressor would be helpful. It is possible the pressure switch could also be part of the on/off switch.

Les.

Good question as I plan to do the same (remote switch on cheapy screwfix compressor) and saw the same "warning" in the manual.

I really can't see the problem in using a remote switch anytime that the compressor isn't running? Whether it's completely discharged, at some intermediate pressure due to some leakage/use since last powered off or at full pressure?

I have noted no loss of pressure at all from full over at least a week of non-use. I suppose I shouldn't really leave it like that though…

Assuming you have the common push button on-off switch with subsidary pressure operated contacts the simplest way is to leave the compressor mounted switch on all the time and put your remote contactor in the feed to the compressor switch. Worked fine for a goodly number of years on my old compressor which, like yours, lived in a hutch outside the workshop for noise abatement reasons. Another advantage was that the reomote contactor made the system NVR so the compressor wouldn't automatically restart if power was lost. The standard switch and pressure control dooby had a simple mechanically locked pushbuttons.

Clive

I have the same problem with my small compressor, which is a Clark with a 3hp 2860 rpm motor. If you use a contactor to control the feed to the compressor it will work fine a long as the contactor stays on till the compressor is full and switched off by the pressure switch, which also dumps the pressure between compressor and tank. If the contactor switches the power back on without dumping the pressure, it will blow the 13A fuse in the plug. This always happens when I am going round the workshop last thing turning everything off, and the compressor is running, and I turn it off at the wall instead of using the red pull up/push down switch on the pressure switch. Turn it of on the compressor, and it dumps the pressure in the feed pipe regardless of whether the tank is full or not, so when you restart, no problems. To put it simply you cannot control this type of compressor with a contactor on the feed. Why not put a long control rod from the switch to the outside of the soundproof cabinet, or use a cycle brake cable to operate the switch. There is a way round this, but it depends on using the switch on the compressor to control the relay in such a way that when you switch off the contactor, the compressor continues to run until the tank is full, the back pressure is dumped, and then the pressure switch interrupts the feed to the contactor, and the compressor will not restart, even if the pressure drops. when you next turn the contactor on the compressor will restart when it needs to, or instantly if the pressure has dropped overnight. Having thought about that it is getting so complex that it would probably be easier to remote mount the pressure switch and extend the air pipe to it. I will look at mine tomorrow, and may come back with a solution.

Phil