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Pump motor overheating issue

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stfinder

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Does anyone have any experience working with pump motors?

I’ve been having an issue with my pump where it overheats after ~5 minutes of spinning. The fan is doing its job to keep the outside cool but it is still shutting off. I’m thinking there is some kind of malfunction in the shut-off circuit and that’s what I’m curious about - how does the pump know to shut off when it gets too hot? Has anyone here ever disassembled pump motor before? How might I be able to troubleshoot this issue further?

If correcting the issue is simply a matter of replacing a circuit component, I’d much rather do that than spend a bundle on a new pump. Any suggestions are greatly appreciated!
 

day_trippr

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There is a bi-metal thermal cutout switch bonded to the motor core. I have one on the big squirrel cage ventilation blower mounted near the ceiling in my brew space and before I ran a dedicated cold air plenum to the motor it tended to thermal-shutdown in middle of heating the day's brew liquor needs - both bg14 burners running pretty hot.

There's always the chance your thermal switch is not to spec and cutting out at too low a temperature.
Or not: I've seen folks mounting pumps inside tool or ammo boxes and the like and until they provided sufficient airflow they had similar issues...

Cheers!
 

doug293cz

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There is a thermostatic switch somewhere near where the electrical connections are made. Design of the specific pump will determine how easy it is to replace that thermostat.

Is the pump out in the open air, or have you put it in some kind of enclosure? An enclosure can limit airflow around the pump and inhibit cooling.

Brew on :mug:
 
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stfinder

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Yeah, I keep the pump in open air and understand the need for good airflow. The fan on the pump seems to be doing its job just fine - the outside stays quite cool.

The outside does heat up a lot when the pump is shut off from heat dissipating from inside. I ended up disassembling the motor and took a picture of the core. I think that’s the TP circuit between 1 and 2 o’clock. Looks hard to access...
 

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day_trippr

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I could be wrong but I believe you can just see a bit of the thermal cutout switch at 10:30 in the pic, and the lumps at 1-2 are splices from the line cords to the coils. You wouldn't want to insulate the cutout from the windings as those splices are...

Cheers!
 
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stfinder

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Ah ok I was wondering what that other bit was. That makes more sense. Still, looks pretty difficult to access with it zip-tied to the coils and all. Any suggestions?
 

day_trippr

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I expect you'd have to remove the entire field winding assembly. From that one pic it isn't obvious what holds it in place, are there screws through the case that aren't shown?

The concern is you'll need to restore the alignment of the field and rotor and that could be a tricky bastid...

Cheers!
 
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stfinder

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That sounds like a whole lot of trouble. Even with it open, it's not clear what holds it in place, there certainly aren't any visible screw heads. I think I'll contact the manufacturer and see if I can't get the complete motor assembly replaced...
 

DaveKnott

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The only time we have seen these symptoms is when a 120V pump is running on 240V. In the cases we have seen, it was due to a mis-wiring of the outlet, where what was supposed to be neutral was hot.
 

DaveKnott

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The only time we have seen these symptoms is when a 120V pump is running on 240V. In the cases we have seen, it was due to a mis-wiring of the outlet, where what was supposed to be neutral was hot.
This can happen when a double-pole breaker is snapped into the panel 1/2 step off, and not picking up both poles like it should.
 
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