On Nov 28, 5:11*pm, "Greg O" wrote:
....
You may be able to find specific controlls for your compressor, but Grainger
has unloaders for gas powered compressors. All they do is bypass the
discharge to atmosphere.http://www.grainger.com/Grainger/items/4TK14?Pid=search
Greg-

That's a lot more complex than the Load Genie I've had on my homebrew
electric compressor since the late 70's. It has a sliding valve
operated by the pressure difference between the head and the tank.
Soon after the electric compressor stops the valve slides to seal off
the tank and bleed the line to the head. When the motor starts it
bleeds air briefly, then slides to close the bleed vent and open up to
the tank. Side loading from the plumbing can jam it.

My little Campbell-Hausfeld tankless compressor has an adjustable blow-
off calibrated in pressure. It won't start with much back pressure so
I have to turn it on before connecting an external storage tank. It's
fine for inflating tires out back where I have electricity but not
piped air, but very inefficient for prolonged intermittent use with a
tank.

You could rig up a temporary equivalent from a water-heater relief
valve and separate manual bleed and tank inlet valves.

I watched a gas compressor on a logger's truck recently. It ran at
full speed to fill the tank and then dropped to idle and vented the
compressor head. After he had drawn the tank down a ways the engine
kicked back to full speed. The engine was a Honda. I didn't see a name
on the rest of it, which was mounted too high to examine closely.

jsw