There are two capacitors (one start, One run)
the leaking relief valve isn't what is causing the motor to throw a breaker. It may be making the compressor run more often, but that shouldn't be a problem.

 

But what's the relief line do? I plugged it off because it was leaking. Could it be to relieve excess head pressure? Could this be why it's hard to start?

Thanks

Edwin

 

Usually most of those smaller compressors have a bleed valve built into the head. That bit of air you heard leaking out was the head pressure. When it is working properly this will allow the motor to restart the compressor without as much stress. This bleed valve is usually activated by the switch, Motor off and Air out with one movement. This allows a smaller motor to run a bit bigger load by lowering the start load.

Did this make sense?

 

Yes it makes perfect sense. I guess I have a leaky pressure relief switch so I'll remove the plug tomorrow and see if that fixes the problem. I'll need to tear into the switch to see if it just needs an O-ring or something.

It's always something! (Gilda Radner - RIP)

Edwin

 

The relief valve is a safety switch required on all pressure vessels. It prevents the tank from being over pressureized.
If for some reason, the motor fails to shut off at the set pressure, the relief valve keeps the tank from blowing up.
On a side note, at one time we had a 30 gallon tank in one of our shops that was built as an oil transfer station. Oil could be pumped from a drum into this tank, then shop air was applied to push the oil at higher pressure into our equipment. With a meer 60 psi of air applied, the bottom of the tank failed (mostlikely due to rust). the drum went thru the shop roof 15 foot above the floor, passing thru a florecent light assembly and landing on the roof hard enough to leave a large dent in the roof.
Compressed air stores a considerable amount of energy and should really have a relief system installed.

 

I had the same problem with mine. Talked to a local eletric company about it and gave them the specs and said that on start up it would draw a little over 20 amps. Installed a 30 amp breaker and problem is solved. They said it was not a problem for it to draw that kind of amperage on start up and replacing the breaker would not hurt a thing. The wiring was ok for the 30 amps also so no worries there!

 

It HAS a 150 psi popoff valve which works fine. I assume that's what you mean. I'm talking about a secondary line running from the point where the compressor runs into the tank to the side of the switch. It leaks air so I plugged it off. The popoff valve and the pressure switch both work fine and there is no way the compressor could pump air faster than the popoff valve could bleed it off in case of a stuck pressure switch.

My question seems to have been answered however in that the relief tube is to allow the motor to start more easily. Where it goes into the side of the switch is where it's leaking so I need to remedy that and remove the plug in the line.

Thanks

Edwin

 

Check the check valve. This should stop flow from the tank back to the head. Probably the cause of the continued leak.

 

when a compressor stops it is suppose to relieve the pressure on the head. if it doesn't most of the time it will pop the breaker because there isn,t enough power to start under the air pressure load. check this before you tear into the electrical.

 

Funny, I have the little 30 gallon Sears compressor and it recently started blowing the breaker on startup. Have to check into some of the options mentioned here. Its what I get for having to compromise on size and voltage.

 

edwinsmith, arkansasram is right, the problem is not in the switch, but in the oneway valve. I don't know how yours is made ,but on mine there is a line from the top of the tank to the compressor head, there is a oneway check valve on this line where it goes into the tank. I think if you replace that you will be fine. Whats happening is it is stuck open and not releaseing pressure off the head, therefore making it difficult to start.

 

My check valve is fine. It will set for weeks without losing any pressure. I took out the plug from the pressure relief line and fixed the startup problem. But it still blows air out of the little dingus the relief tube screws into on the side of the pressure switch. It seems like this should be a valve that gets closed once the switch turns on but opens when the switch turns off to relieve the head pressure for the next startup. I'll need to check with Sears to see if they have a new valve.

[Edit] There is no call out for the valve on the side of the switch so it is probably sold as part of the pressure switch. What a PITA. Sears probably gets $50 for the whole switch.

Edwin

 

probably alot more

 

see if you can find a stand alone pressure control switch?? and wire it into the mess... i have seen some in the plumbing sections of home improvment stores where they have the jet pumps for well water systems... if you can find one rated for ~200psi and adjustable, you can set it up for like 125c/out-110c/in.. the ones i have seen are not really expensive [just plain squareD ones- and pressure is pressure (liquid or gas)]

 

Thanks for the idea. I'll check the hardware stores. We have an Orschelins a few blocks from here. They also sell air equipment and they might even have the whole switch or the little valve I need.

Edwin