Unloader Valve

4 months 1 week ago #2464 by oldpackrat

I have watched your online video for air compressor unloader valves. The unloader valve on my Furnas pressure switch looks a lot like the one shown in your video. My pressure switch says it goes on at 80 and off at 100. Does that mean that I have to buy a replacement unloader valve that is rated for on at 80 and off at 100? I turn my pressure switch on and it fills the tank then shuts off, I draw down the air in the tank, and at some point the compressor senses the pressure loss and turns on. Only when it turns on automatically, it struggles for about 10 seconds and blows the 20 amp circuit. Is the Furnas unloader valves you sell universal in terms of on and off pressures? If the unloader valve is pressure rated do you have, can you order, or do you know who manufacturers unloader valves rated on at 80 and off at 100? I am stupified by this damn unloader valve. Machine is Sears electric 1HP twin cylinder compressor and is from 1980, (106.175541), don't want new pressure switch, just
unloader valve on the side. It is lightly used and looks like new, always kept in garage. no dirt, no rust. HELP! HELP! HELP!, PLEASE RESPOND. Thanks!

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2 months 3 weeks ago #2554 by MTR-Admin

Thanks for the post oldpackrat!

Also, I apologize for this late reply to your question.

To answer your main question...no, unloaders valves aren't rated for specific pressures, so many manufacturers usually use the same unloader valve on most of their pressure switches no matter the PSI ratings.

Second, what you have is actually a bad in-tank check valve, not unloader valve. The check valve is the one-way valve in the main tank inlet in which your main discharge tube is attached to (from the pump head). It's probably clogged with debris and staying open after the unit shuts off, thereby back-feeding air through the lines and out of your unloader valve. Cleaning (or replacing) the check valve should solve the problem.

- MTR

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