Compressor issue confusing me.

[Robert Engel]

Ingersoll 5HP compressor about 15 yrs old.

Last summer I found it running away – smoke was everywhere, the compressor hot enough to boil water. Shut it down, took to compressor repair shop, they said the unloader valve failed. They replaced regulator and it ran fine for about 6 months.

A couple weeks ago it wouldn't turn on until I pressed the reset button on the motor. Today was the second time, when I hit reset button on motor, it started up, & seemed to run fine and made pressure, except it wouldn’t turn off.

What got my attention was I heard air leaking while it was running. I found it was coming from the unloader valve. When I shut it off, the unloader valve closed after a few seconds like normal.

I should mention about 2 months I replaced regulator because the on-off lever broke. It was running ok at the time. I replaced it with the same model the comp shop used.

I will say the regulator is a Pumptrol, not an IR original, but I figured the comp shop knew what they were doing. The cutoff pressure is 150.

[Ron Selzer]

What pressure was the tank reading when it did not turn off?
Is the compressor worn and not making enough pressure to achieve shutoff setting?
Unloader valve should not be active until pressure switch shuts off.
Might try adjusting high end pressure downward
good luck
Ron

[Robert Engel]

It was at 125 when I shut it off.

[Bill Dufour]

why 150? I would set it for 120 or less and re-pulley for more air flow. Does it have a pressure switch or just an unloader. Why did shop replace regulator.. How often have you changed the oil.
If you have a pressure switch you need to have a separate motor contactor to handle the current.
Bil lD

[Ron Selzer]

It was at 125 when I shut it off.

sounds like there is a mechanical problem with the compressor, might get lucky and a new set of valves would fix it.
Right now it has to build pressure above nominal 150(155-160 actual) to shutoff

Ron

[Robert Engel]

Update: I checked the regulator and found out its only rated for 20A.

Sorry, the cut off is 125, not 150. I did notice one of the capacitors was much, much hotter than the other.

Is there a start and run capacitor? How hot should they get?

So it looks like the compressor shop put the wrong regulator on it, and so did I when I assumed they were right. Could have been a simple mistake pulling it off the shelf.

Anyway LSS I've ordered an OE Ingersoll regulator.

Now I'm wondering about the capacitor. Easy and cheap enough to replace so I think I'll do that, too.

[Bill Dufour]

You have me confused. regulators are rated at CFM not amps. Unloaders are mainly for engine powered compressors and really big motor powered ones like 100 horsepower and more.
Bil lD

[Robert Engel]

I am not that knowledgeable, but since there is current flowing, it makes sense to me. I just know the motor is overheating, and I think it’s because the regulator isn’t working correctly.

There may be another reason, but I haven’t gotten enough feedback so I’m going to put the OE regulator back on and see what happens.

On the inside of the regulator cap-445791

[Jerome Stanek]

You have me confused. regulators are rated at CFM not amps. Unloaders are mainly for engine powered compressors and really big motor powered ones like 100 horsepower and more.
Bil lD

My 5 HP has unloader so does my 2hp portable

[Michael W. Clark]

I am not that knowledgeable, but since there is current flowing, it makes sense to me. I just know the motor is overheating, and I think it’s because the regulator isn’t working correctly.

There may be another reason, but I haven’t gotten enough feedback so I’m going to put the OE regulator back on and see what happens.

On the inside of the regulator cap-445791

This is not a regulator. It is the pressure cutoff. It disconnects power from the motor at 125 psi. There should be an adjustment nut to set the ON pressure.

There should also be a small tubing connection that vents the pressure from the compressor when it shuts off at 125 psi.

A regulator maintains a constant downstream pressure as long as the upstream pressure is higher and the regulator flow rating is not exceeded.

[Bill Dufour]

Notice that the pressure switch is rated for only two horsepower at 240 volts, single phase. Unless this the control switch for a contactor designed for five horsepower it is likely the points have either burned or welded shut. I would guess welded shut in your case since the motor never shut off.
Bil lD

[Bill Dufour]

My 5 HP has unloader so does my 2hp portable

An unloader built into a little 2hp pump seems expensive. Does it really save any thing on the 5hp over a pressure switch? It does reduce the number of starts on the motor which will reduce motor wear I suppose. Does the 5hp have an oil pump and filter?
Bil lD

[Ron Selzer]

An unloader built into a little 2hp pump seems expensive. Does it really save any thing on the 5hp over a pressure switch? It does reduce the number of starts on the motor which will reduce motor wear I suppose. Does the 5hp have an oil pump and filter?
Bil lD

I believe there are two different parts with the same name being used and confused in this thread.
Engine driven compressors bleed off air above set point to keep air pressure regulated
Electric compressors bleed air off of cylinders when pressure switch is open so that the compressor starts unloaded.
Ron

[Bill Dufour]

Ron I think you are right. I now think he means the little pop valve on the pressure switch but he never said pressure switch.

[Robert Engel]

Notice that the pressure switch is rated for only two horsepower at 240 volts, single phase. Unless this the control switch for a contactor designed for five horsepower it is likely the points have either burned or welded shut. I would guess welded shut in your case since the motor never shut off.
Bil lD

Sorry for the mistake in terminology. Yes I’ll talking about a pressure switch, not regulator.

What do you think about the capacitor getting so hot? Is that normal?

[Michael W. Clark]

Is there also a mechanical pressure relief? Not sure the setting but it should open to protect the tank.

If your replacement switch was set for 150 instead of 125 Psig, it may not have been good for the motor. If it was smoking, then you may have some damage.

I assume this is belt driven, could the smoke have been coming from the belts slipping? Not sure that is likely since you are having issues with motor and having to hit reset switch.

The Square D Pumptrol is a good switch and likely equal or better than OE parts. They are relatively inexpensive too. If you still have original switch, take it to your electrical supply house and get a replacement Pumptrol. There are a lot of different models of the Pumptrol

[Jerome Stanek]

An unloader built into a little 2hp pump seems expensive. Does it really save any thing on the 5hp over a pressure switch? It does reduce the number of starts on the motor which will reduce motor wear I suppose. Does the 5hp have an oil pump and filter?
Bil lD

Most compressors I have seen have an unloader to relive the pressure so the motor can start after the compressor shuts down. You you hear it hiss a little just after it the motor stops.

[Rod Sheridan]

I am not that knowledgeable, but since there is current flowing, it makes sense to me. I just know the motor is overheating, and I think it’s because the regulator isn’t working correctly.

There may be another reason, but I haven’t gotten enough feedback so I’m going to put the OE regulator back on and see what happens.

On the inside of the regulator cap-445791

The confusion is because that’s not a regulator, it’s a pressure switch.

Most non industrial compressors are only rated for intermittent use, the motor will be marked “compressor duty”. If you have an air leak or consume too much air volume the compressor will run continuously and may overheat....Rod.

[Brice Rogers]

I think that the capacitor getting hot is a big clue. It also could be related to the electric motor working a bit too hard/getting hot. A new capacitor costs less the $20 in most cases. So, it is worth replacing and see if it helps things.