oil burner motor overloads

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Old 01-03-13, 11:47 AM
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oil burner motor overloads

The overload button on my oil burner motor occasionally trips … it has tripped three times in the last 6 months. This causes the relay that monitors the flame to also trip.

I have unfortunately never oiled the motor … until today. I just added several drops of light machine oil in each of the two ports today.

I tried to determine if there was any bearing problem as follows. I rotated the transformer out of the way so I could touch the blower blades … and spun it by hand. The motor turned easily by hand before I added the oil. It continued to turn a quarter turn after I let go of the blades … seemed about normal … I did this both before and after adding oil and did not detect any difference. Sure, it’s hard to really know whether the bearings are right, what with the pump also connected. But the shaft feels like the bearings are normal, and there is no sound from the bearings. From all this, I find it a bit hard to imagine that the lack of bearing oil would cause overload.

My questions:
  • Any thoughts on why the motor overload trips? Is this issue probably due to my failure to oil the bearings?
  • Do these motors frequently fail on their own?
  • Should I be concerned about whether the pump is causing the overload?
  • Is my oiling it now sufficient … or should I replace the entire motor in order to improve reliability?
I need to be able to rely on the furnace to keep the house warm, when I’m not at home … I live in New England.

Here’s the equipment (about 33 years old):
  • Dynatherm Furnace FPB 24A
  • Carlin 100CRD Burner
  • Westinghouse 316P937 Motor (1/7 hp, 3450 RPM)
  • Honeywell R8184G4066 Flame Monitor Protection Relay
My last oil burner cleaning was 8 months ago, and it has used 250 gallons since then. (I heat mostly with a wood stove when I'm home.) The first time the motor overload tripped was a couple months after I last cleaned it … so it was not at all dirty at the time … thus this motor trip issue is not the result of needing standard oil burner cleaning service.

Thanks!
Andy
 
  #2  
Old 01-03-13, 11:54 AM
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Not my strong point in service but I thought that the cad eye also tripped the breaker.
So lack of flame would trip it same as a motor issue.
 
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Old 01-03-13, 12:48 PM
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PJmax,

Thx for responding ...

... but, no, you're talking about the "other" reset. The CAD eye causes the primary control button to trip if there is no flame. I'm talking about the overload button on the motor. In my case, the motor trips ... and then this causes the primary control button to also trip. (There is no way the CAD eye can cause the motor overload to trip.)

Other comments, anyone?

Andy
 
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Old 01-03-13, 08:15 PM
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Only two things can cause the motor overload to trip. One is the motor is going bad (would not be a surprise if it's 33 years old). The other is there is too much load on the motor.
Turn off the power to the heater, open the ignition transformer, & turn the burner blower wheel by hand. Is it stiff? Has the coupling between the motor & the pump been replaced (maybe at the last cleaning)? The coupling could be just a tiny bit too long thus causing extra drag on the motor.
 
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Old 01-03-13, 10:33 PM
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Grady,

Thx for the advice.
[INDENT][COLOR="#0000FF"]>> ... turn the burner blower wheel by hand. Is it stiff? > The motor turned easily by hand ... It continued to turn a quarter turn after I let go of the blades … seemed about normal … > Has the coupling between the motor & the pump been replaced (maybe at the last cleaning)? The coupling could be just a tiny bit too long thus causing extra drag on the motor.
 
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Old 01-04-13, 03:38 PM
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From what you are saying about the motor being able to turn about a quarter turn with the pump attached, it doesn't sound like there's excessive drag on the motor due to the coupling or pump.

I think I'd just replace the motor. When you do replace it, get a PSC type motor. Here is one which will work: Patriot Supply - 21805U
 
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Old 11-04-13, 06:25 PM
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Well, what happened?

I have the exact same motor as you. My reset button is popping as well. i reset, motor on flame ignites 15 seconds later shuts down and reset button pops? Did you ever figure it out? Let me know please as am going nuts and of course its the first 35 degree night of the fall here on Long Island. Thanks.

~Keith~
 
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Old 11-04-13, 07:18 PM
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Is the reset on the motor itself tripping or is the reset on the control box (primary control) the one that is tripping?
 
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Old 11-07-13, 06:42 PM
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Rest on motor. isolated just motor wired the 2 wires, stood upright held with legs so dont move turned on power. spins fast and quiet then 10 seconds later rest pops out and shuts down. Pretty sure its motor at this point as nothing else is a factor with that test correct?
 
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Old 11-07-13, 07:23 PM
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Darned good chance it's the motor since there is no other load on it. I would use a PSC motor such as this one. Patriot Supply - 21805U
 
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Old 11-08-13, 07:13 AM
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Motor

I was actually looking at that one. What is PSC? It matches all other specs but mine doesn't have the black thing on the side? Should work though right?
 
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Old 11-08-13, 07:37 PM
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The thing on the side is a capactior. It makes the motor more efficient. The PSC (permanent split capacitor) motors are all I've used for the past 15 years or so.
 
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Old 11-08-13, 08:18 PM
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I picked up an AO Smith OBK6002V1. Do I have to open motor to wire it or something as I see wires wrapped in circle inside rubber banded together. How do you open after take 4 bolts off?
 
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Old 11-09-13, 03:49 PM
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I have never, ever seen an oil burner motor which didn't have either a cord (most commonly) or 2 wires sticking out of a threaded hole. It should look like the pictures here: OBK6002V1 Oil Burner Furnace Motor for Beckett 21805U Nordyne 621945 R21805U
 
 

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