New pump motor running very hot, shutting off

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CGPoolman
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New pump motor running very hot, shutting off

Postby CGPoolman » Sat 28 Apr, 2012 18:08

I have a problem and need some guidance on how to proceed. I replaced the motor on this pump Friday 4/27. I got a phone call from the homeowner today reporting that the pump was running for about 20 minutes and shutting off. I went out to the house and checked it out.

1) I tested the power at the timer, getting 120V on all 4 terminals
2) Tested power at the pump, getting 120V on both lines
3) Pump motor is very hot to the touch. Not enough to burn you, but hot enough where you can’t hold your finger there.
4) I checked all my wires to make sure they are tight. No loose wires in the timer box. I disconnected and re-connected my wires to the pump to make sure they were good. Also checked to make sure the switch in the back was set to 230V.
5) The motor sounds great when it is running, no strange noises or anything that I could notice.

I started the pump back up and let it run for a while (approx 15 minutes) before leaving. I asked the homeowner to call me if it happened again. She called about 30 mins later to tell me it shut off again. So that time, the pump ran for about 45 mins before shutting off. Is it possible that there is a defect in the motor itself? I feel like I have checked and tested everything I know how to check, I’m not sure how to proceed here. I've done a lot of motor replacements - I know its not uncommon for the motor to get hot, but I’ve never seen one shutting off like that.

Details: Pump is a 1 HP model RS1000 - it is the Leslie's Pool version of the Hayward Super II. The motor I put on it is an AO Smith Round flange 1HP, was brand new in the box. I also replaced all the seals with a standard Go Kit. Pump primes right up and has a great return into the pool, so I don't think I have any clogs or obstructions.

I've read some troubleshooting articles, and I am thinking either the motor has a defect, or it has something to do with the actual power supply tapering off - this is in Florida, and this is one of the first 90 degree days we've had this year so it is likely that the entire neighborhood is cranking the AC but the homeowner has never had this problem before.

Any insights are appreciated!

-CG


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mas985
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New pump motor running very hot, shutting off

Postby mas985 » Sun 29 Apr, 2012 13:23

If the voltage is too low or too high, that can cause a motor to overheat. Can you measure the voltage at the motor?


Other possibilities:

The new motor total HP (Label HP * Service Factor) is less than the old motor.

Another possibility is that the seal was installed backwards by mistake.
Mark
Hydraulics 101 ; Pump and Pool Spreadsheets ; Pump Ed 101
18'x36' 20k gallon plaster/gunite pool, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge Filter, Solar Panels, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater
CGPoolman
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Joined: Sat 28 Apr, 2012 17:52
Location: Orlando FL

New pump motor running very hot, shutting off

Postby CGPoolman » Sun 29 Apr, 2012 14:32

Mas985,

Thanks for the reply. I'm going back to the house on Tuesday to check a few more things. I tested each line individually in the timer box and on the back of the pump the first time around. I need to test them together to make sure I have the correct voltage going into the timer, and into the pump. If the electric checks out, I'm going to pull the pump apart and double check my work. Make sure the impeller is not binding up etc. I feel pretty confident I put the seal in correctly (ceramic to ceramic) but you never know. I'm bringing another motor with me - if I can't find anything wrong with the electricity or the pump assembly I think I've ruled out everything but the motor.

-CG
CGPoolman
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New pump motor running very hot, shutting off

Postby CGPoolman » Wed 02 May, 2012 09:58

Ran a few more tests - I have 240V at the timer where power goes in, and 240V where power goes out to the pump. 240V at the back of the pump. I went ahead and replaced the motor, primed the pump, and turned it back on. It ran for about 7 minutes and shut off. I gave it a few minutes and turned it back on, this time I kept my elect testers on the back of the motor. Took about 5 mins for it to shut off this time, but it held 240V the whole time, no spike or drop in power. Going to try replacing the impeller with the possibility that it is warped and rubbing somehow, I fell like I have eliminated everything else as an option. If that doesn't work, I'm thinking complete pump replacement because I'm out of ideas at this point and my customers pool has been down for almost a week.
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mas985
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New pump motor running very hot, shutting off

Postby mas985 » Thu 03 May, 2012 18:55

Also, check the part# of the impeller to make sure it is a match to the motor.
CGPoolman
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New pump motor running very hot, shutting off

Postby CGPoolman » Thu 03 May, 2012 20:54

Mas,

The impeller was a bit warped. I pulled the impeller and when I looked real close I noticed it had gouged into the diffuser a little bit. It was easy to miss. I replaced the impeller/diffuser and reassembled the pump. It primed right up but shut off again after about 3 minutes. I started the pump back up several times it averaged between 5-8 minutes before shutting off. There's no way 2 brand new in the box motors are bad. I've made every reasonable attempt to repair this pump - I'm going there tomorrow with a brand new Super II pump and just replacing the entire pump because this old one is obviously possessed by demons or zombies or something.

-CG
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mas985
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New pump motor running very hot, shutting off

Postby mas985 » Fri 04 May, 2012 13:48

Again, did you check the part# on the impeller? It could be a mismatch to the motor.
Mark
Hydraulics 101 ; Pump and Pool Spreadsheets ; Pump Ed 101
18'x36' 20k gallon plaster/gunite pool, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge Filter, Solar Panels, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater
CGPoolman
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Posts: 168
Joined: Sat 28 Apr, 2012 17:52
Location: Orlando FL

New pump motor running very hot, shutting off

Postby CGPoolman » Fri 04 May, 2012 16:32

Mas,

Yes, impeller was a 3010-C. I installed the new pump today, everything is working great. I have the old pump in my truck, I'm going to experiment with it and see if I can't figure it out.

-CG
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mas985
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New pump motor running very hot, shutting off

Postby mas985 » Fri 04 May, 2012 18:22

That is a 1 HP full rated impeller so the motor needs to be 1 HP full rated as well. What is the service factor of the motor? It needs to be 1.5 or greater.
Mark
Hydraulics 101 ; Pump and Pool Spreadsheets ; Pump Ed 101
18'x36' 20k gallon plaster/gunite pool, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge Filter, Solar Panels, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater
CGPoolman
Swimming Pool Pro
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Posts: 168
Joined: Sat 28 Apr, 2012 17:52
Location: Orlando FL

New pump motor running very hot, shutting off

Postby CGPoolman » Sun 06 May, 2012 14:07

Mark,

I scoured the label of the replacement motor I had on there, and noticed a few things:

Service factor of 1.1 (AO Smith UST1102)
Amps - the label says it is rated for 13 amps, my meter was picking up 15. The Motor on the new pump I ended up installing was rated for 15 amps.

So, it could have been any one of these factors, or some combination of them all (Amps/service factor/bad impeller). It was a learning experience for me, I'll know now to check ALL of these things when replacing a motor. First time I have ever had this problem, and I've done my share of motor jobs over the years. This was the first time I ever worked on one of the Leslie's pumps though.

Thanks for your input,
-CG

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