Return to the Heating & Air Conditioning Forum | Post a Follow-Up

 o
Oil burner is triggering motor reset button and won't start

Posted by tiffanys (My Page) on
Fri, Oct 29, 10 at 20:06

The burner on my oil furnace has a motor reset button or safety button on top of it that pops out and shuts off the burner if there is a problem. I'm trying to find out what types of problems would trip this button.

Wednesday I went to shower and had no hot water as the furnace wasn't running. I pressed the reset button on the stack control and the motor reset button on the burner and the burner started. I checked the fan for a blockage - didn't find any and cleaned the end of the stack control.

Furnace ran fine until early evening on Friday when the button popped again on the burner. I pressed the reset button on the motor and the stack control and this time the furnace won't start. Any help in troubleshooting the root cause would be appreciated! Thank you!


Follow-Up Postings:

 o
RE: Oil burner is triggering motor reset button and won't start

The problems could be: Sooted up boiler passageways, improper air supply, blocked fuel filter and fuel starvation at the pump, worn electrodes, dirt on the cad cell eye, smoky flame. The primary control on the burner is shutting down from any of these problems which can affect the flame.

If you have a power venter,(no chimney) the proving switch could be faulty. There is a 1/4" tube in the power venter that operates on sensing air movement to operate the power venter proving switch/diaphragm. This tube can be blocked with soot. All these things can shut down the burner.

If you don't understand any of these terms, you'll need to get someone in fix your unit.


 o
RE: Oil burner is triggering motor reset button and won't start

Thanks for the response! This morning, Saturday, I pressed the reset button on the stack controller and the burner started up. I shut it off and then replaced the filter, replaced the strainer, brushed and vacuumed the inside - then I started the furnace back up and it ran. The flame, from my untrained eye, looks ok, not dark or smoky. I'm not convinced this will solve the problem as it has been less than a year since this was last done.

I don't have a power venter.

A technical at the hardware shop showed me where the cad cell eye is on a burner they had in the store. Still need to locate on mine and will then clean it off.

How would I know if the electrodes are worn?

Thanks for the help!


 o
RE: Oil burner is triggering motor reset button and won't start

Generally, there is an air gap of 1/8" between two pointed electrodes. This gap is located about 5/16" above and about 1/16" in front of the center of the nozzle. Specs vary according to manufacturer, but that's close. Worn electrodes are rounded and spaced far apart. The air from the motor can blow out a spark if the ignitor is weak. Carbon under the two ceramic electrode clamps can short out a spark too.


 o
RE: Oil burner is triggering motor reset button and won't start

If you have a stack control you won't have a cad cell. None of the afore mentioned issues will cause a motor reset. It's either the motor or the pump. Sometimes an older pump will stick and the motor doesn't have enough torque to break it free. In this case, since the motor will generally restart, I don't think that's the problem. You most likely have an older motor with a centrifigal start switch. With age they tend to hang up sometimes in the run position so on the next cycle it's trying to start on the run windings.

If your furnace is old enough to still have a stack control it's old enough to be carted out to the junk yard. A new one would cut your oil bill considerably.


 o
RE: Oil burner is triggering motor reset button and won't start

Pushing both resets makes it impossible to determine which is the problem. Next time, push only the button on the motor. If the furnace starts, the motor or the pump is the problem and an amperage draw measurement is needed on the motor. If it does not start, push the reset on the primary control. The next time after than push only the reset on the primary control. See which is the problem and deal with just the causes involved.


 o
RE: Oil burner is triggering motor reset button and won't start

If the motor reset trips then the primary reset will trip. If the primary reset trips first there will be no power to the motor, therefore it won't trip.


 o
RE: Oil burner is triggering motor reset button and won't start

As dapoppa noted, I don't have a cad cell. The electrodes look ok - no cracks and the ends have a point. I also replaced the nozzle while I was in there.

The safety on the motor continues to pop, requiring a reset.

Improper air supply is still a possible root cause.

The motor being bad due to the centrifugal start switch is still a possible root cause. Where would I begin to research motors?

Can you think of anything else that could cause the safety on the motor to be tripped? Bad aquastat? Bad thermostat?

Thank you!


 o
RE: Oil burner is triggering motor reset button and won't start

If the reset on the motor trips repeatedly and the pump/burner blower combo turns freely, replacing the burner motor is in order.


 o
RE: Oil burner is triggering motor reset button and won't start

Look on the Grainger website. Compare the data on your motor's plate. You're probably looking for a 1/6HP, 1/7th or 1/8HP motor. You need to know the rotation and RPM (1750 or 3450) Rotation is viewed from the shaft side.

There are only a few motors for oil burners. Your style would be like the Grainger 4MA10, but without a dust cover and the proper RPM.


 o
RE: Oil burner is triggering motor reset button and won't start

To address the possible root cause of improper air supply, today I removed the pipe from the furnace to the chimney to see if there was any blockage. There was a small pile of soot on the back of the furnace and on the entrance to the chimney. I don't think enough to cause the safety to trip. In the chimney however there was a lot of soot at the base of the chimney. I took out about a foot of soot in the bottom and there could be more but the hose on my little shop vac wouldn't reach further. I'm assuming that is not supposed to be there, is that correct? Could this building soot create an improper draft that would pop the safety reset?

As for the motor, you are right, there is only one that matches the specs of the one I currently have - Grainger Item # 4MA12. If this model is installed does that mean I no longer need a stack controller?

http://www.grainger.com/Grainger/oil-burner-motors/hvac-motors/motors/ecatalog/N-9y9Z1z0nw85


 o
RE: Oil burner is triggering motor reset button and won't start -

Just wanted to add that I have been in this house for five years and neither I or anyone I have hired to clean the furnace has ever opened the piping to the chimney to see what is in there. So the soot/debris has been accumulating at least for the past five years.


 o
RE: Oil burner is triggering motor reset button and won't start

If your motor reset is kicking off, it has nothing to do with soot in the chimney. It is because the motor is overheating from a high amp draw. Possibly from a failing fuel pump.

You have a stack switch which I've only seen in training schools. The best thing you could do is to install a new Beckett AFG burner or equivalent and keep your old boiler. A new burner would have a primary control, burn much cleaner, and use less oil. The stack switch would be gone.

Figure about $500 plus installation. Or you could call an oil burner guy and maybe find a used one, possibly for free. Sometimes boilers get junked and the burner is still good. Just look for an AFG. Age doesn't matter all that much.

If your motor is shutting down because the stack switch is sensing an outfire, it wouldn't cause it to reset.


 o
RE: Oil burner is triggering motor reset button and won't start

sigh... I hear what your saying.


 o
RE: Oil burner is triggering motor reset button and won't start

tiffanys seems intent on confusing the issue. If the overload on the burner motor actuates, it is because the motor overheats. That would be because of excess mechanical load or electrical problems within the motor. Period!!!!
New stack-mounted primary controls are available, Grainger # 2E521.


 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!


Return to the Heating & Air Conditioning Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Please review our Rules of Play before posting.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.


Learn more about in-text links on this page here