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Old 07-30-2009, 01:14 PM   #1
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My pool pump motor casing (Hayward, 1.5 hp, 240 V) is very hot to the touch. (To leave your hand on it for more than 1 or 2 sec is painful.)

Water flow is fine, the skimmers and filter basket are clear, filter pressure is normal. Pump/motor assembly doesn't sound any different.

Motor is labeled that it has 50 deg C thermal protection. That's 122 deg F. I would think I could touch 122 F for quite a while, but the motor has never cut out.

Motor casing is sealed, so there are no air vents to be blocked.

Any thoughts on what's wrong or how to trouble-shoot?

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Old 07-30-2009, 02:18 PM   #2
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Originally Posted by cgoll View Post
pool pump motor casing (Hayward, 1.5 hp, 240 V) is very hot to the touch.
(To leave your hand on it for more than 1 or 2 sec is painful.)

Motor is labeled that it has 50 deg C thermal protection. That's 122 deg F. I would think I could touch 122 F for quite a while, but the motor has never cut out.

Any thoughts on what's wrong or how to trouble-shoot?
Check voltage & current into the motor, check that the shaft spins freely with nothing on it.

Re: 50C

no burn ever at 42C
burned in 30 sec at 54C
5 sec at 60C
1 sec at 71C


Last edited by Yoyizit; 07-30-2009 at 02:20 PM.
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Old 07-30-2009, 08:45 PM   #3
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Look on the nameplate and see if there's an 'insulation class' or 'ins.cl'. It'll be a letter, A, B, F, or H. Most likely B or F. This is the maximum temperature that the insulation of the windings can operate at.

A = 105C - 221F

B = 130C - 266F

F = 155C - 311F

H = 180C - 356F

The 50C rating is simply the maximum ambient temperature that the motor can be operated in while producing its rated HP at nameplate voltage. Any hotter and the maximum insulation temperature will be exceeded.

Thermal protection simply means that it has a built-in overload device (usually sensitive to current, not temperature), and an outside one isn't needed. It might say auto reset, or manual reset.

Shell temperature isn't really a good indicator of operating temperature, but if you can hold your hand on the shell for more than a second or two, it isn't overheating. If it smells like its burning up, or if the paint starts to discolor or peel, that's trouble.

I think your pump is operating normally.

Rob
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Old 07-31-2009, 12:21 AM   #4
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If it ain't broke don't fix it......
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Old 07-31-2009, 08:39 AM   #5
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H = 180C - 356F
Solder melts at ~380F. The internal connections in these motors are welded, or what?

Last edited by Yoyizit; 07-31-2009 at 10:13 AM.
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Old 07-31-2009, 10:19 AM   #6
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OK, I'll go w/ remcoair's advice for now and just leave it alone. But I do think the shell color has changed recently. Looks like I better start researching the best price for a replacement.

More money into the pit! I think only a boat could be worse!
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Old 07-31-2009, 10:45 AM   #7
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Originally Posted by cgoll View Post
OK, I'll go w/ remcoair's advice for now and just leave it alone. But I do think the shell color has changed recently. Looks like I better start researching the best price for a replacement.

More money into the pit! I think only a boat could be worse!
You have to remember that rolled steel motors like you have, get hot for a REASON. They have to dissipate heat. The heat is dissipate through the rolled steel frame. This is normal. Some discoloration over time is also normal. Plastic nameplates will roll up on the edges and change color some. This is normal also. Serious overheating will trip the automatic overloads built into the motor. If it's not tripping you should be just fine.

One more thing. If this motor ever craps out and needs replacement, do not just change out the motor. Change out the whole assembly. Most people including professionals sometimes never get these pump motors put back together. There are several parts between the motor and pump that are hard to replace. Ever try to pull an impeller off a motor shaft? Ever need a mechanical seal? Just replace the whole thing and install unions for future removal. You will not be sorry.
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Old 07-31-2009, 10:50 AM   #8
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I went out last night and tried the same experiment. I have a 120V Hayward. I couldn't keep my hand on it for more than a few seconds. I'll hit it with the IR later today and see what the actual surface temp is.
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Old 07-31-2009, 10:53 AM   #9
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That would be an interesting data point. I've always wanted one of those IR thermometers....
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Old 07-31-2009, 05:58 PM   #10
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Yoy, anything spliced inside of a motor or generator is crimped. I haven't seen solder in a motor for quite a few years. When solder was used, they didn't use the insulation class letters, but it would have been A or less.

Rob
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Old 07-31-2009, 07:25 PM   #11
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That would be an interesting data point. I've always wanted one of those IR thermometers....
I got readings of 110-125 degrees on the outer housing at 77 degrees ambient. It's a 1.5HP 120V Hayward.
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Old 07-31-2009, 08:08 PM   #12
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I got readings of 110-125 degrees on the outer housing at 77 degrees ambient. It's a 1.5HP 120V Hayward.
That puts it between
no burn ever at 42C(108F) &
burned in 30 sec at 54C(129F)

A motor shell is a low emissivity surface so this might influence your reading in one direction or the other. Probably it would read low.
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Old 08-01-2009, 04:07 AM   #13
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Is that motor sitting where the sunshine can heat it? You'd be surprised at how much heat is added from something as simple as the sunlight hitting it.



Also, check the bottom of the motor for open vent holes. We had one case where those holes were blocked off by sitting too low on the ground. Raising it up just a couple of inches made a big difference in how much heat the motor housing was retaining.

Look carefully at this photo: There are vent holes at the bottom

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Last edited by kbsparky; 08-01-2009 at 04:12 AM. Reason: Added pic for clarity of concept
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Old 08-02-2009, 12:08 PM   #14
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Yoy, anything spliced inside of a motor or generator is crimped. I haven't seen solder in a motor for quite a few years. When solder was used, they didn't use the insulation class letters, but it would have been A or less.

Rob
Not true. All splices inside a rewound motor or new motor are welded not soldered. Motor shops use a torch and braising rods. Manufacturers are automated and also weld internal connections. I have visited Baldor, Weg, Marathon and Leeson and all braise the connections and insulate them with sleeving before tying them down to the coils. I worked in two motor shops, and visited many more. They all braise (weld).
Never saw one crimp ever used inside a motor.

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