Unloader valve - check valve - valve issues

I have a homemade air compressor my grandfather had for years. The problem was it leaked around the tube from the compressor to the tank.


Before I researched some similar problems I didn't know about unloader valves. I found that it had this valve and was actually installed incorrectly at some point leaving it stuck open, allowing pressure to build into the tank but when it reached max pressure it would shut off and slowly bleed out, cycle would obviously continue.

After I realized what was going on I installed it correctly because it was just a matter of reversing the fittings that someone must have messed with. So, now the valve is correctly positioned so the it opens when the compressor is running and shuts when it goes off, and, allows it to unload that short spurt of air off the compressor.

My problem is that while it is filling/running air shoots out of the little unloader valve hole only letting my pressure to build to a certain point and but never reach full capacity.

I can only assume that when that unloader valve is open allowing air to flow to the tank it somehow also shuts the little unloader hole on the side, leaving air to travel in one direction. If I am correct then I know that the valve is bad. If that is not how it works then I don't know what to do. Any advice?

Thanks,

Wayne

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Bill says...

Hi Wayne. The way I'm reading your post is making me wonder if you are using the terminology "unloader valve" for the CHECK VALVE that is usually installed where the air from the pump enters the tank.

Above the check valve is normally a line that shoots over to the pressure switch. This line is upstream from the check valve is it is the line that allows the pressure switch to "read" the tank pressure, so it knows when to trip and shut off the air compressor at cut out.

That same line also plumbs air to the UNLOADER VALVE, often located beside your pressure switch. The unloader valve is closed when the compressor is running, allowing air to be pumped into the tank, and open when the compressor stops, allowing air over the piston to escape, making start up easier.

If you have air bleeding out of the unloader valve all the time, your check valve is not working properly.

Cheers,

Bill

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