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1

Tuesday, June 9th 2015, 4:50pm

Burning out 1HP motors

Hello Ladies and Gentlemen.

Last year I burnt up my 1HP motor and replaced it. It happened again this year. The motor gets very hot even though it is cycling on and off, about 8 seconds on, 8 seconds off. The entire Rainbird system came with the home. I have changed nothing.

Please excuse my ignorance in advance, I have to replace it again, so should I just go to a 1.5 or 2HP motor?

Wet_Boots

Supreme Member

Posts: 5,198

Location: Metro NYC

2

Tuesday, June 9th 2015, 5:19pm

Cycling on and off is a great way to kill an electric motor. Maybe it's time to make a match between the water supply and the sprinkler system.

3

Tuesday, June 9th 2015, 5:39pm

Thats what I thought too. But when it ran constantly (how the first motor died, My air bladder had deflated ) it got so hot it burnt itself out. I was then instructed by the sprinkler shop that I bought my current motor from, that it should cycle on and off. But it still gets so hot it can't be touched.

Wet_Boots

Supreme Member

Posts: 5,198

Location: Metro NYC

4

Tuesday, June 9th 2015, 9:54pm

cycling is a strain - the entire reason for a pressure tank is so that the pump has to run for minutes (not seconds) before it reaches shut-off pressure

5

Wednesday, June 10th 2015, 3:16pm

So the motor should run for minutes? ok I'm not up to speed on how the system is supposed to work then. Is there a tutorial or beginners overview in here I can read to help me understand what it should be doing? Something has changed in my system because everything was fine for 5 years and now I'm burning up motors.

Wet_Boots

Supreme Member

Posts: 5,198

Location: Metro NYC

6

Wednesday, June 10th 2015, 9:04pm

You have to understand that a motor running is not anywhere near the strain of a motor starting. They can run forever when properly installed.

Find the information plate on that motor. Read it, and post here what the service factor is on the motor that burned out. (service factor is abbreviated as SF)

7

Thursday, June 11th 2015, 3:38pm

SF 1.10

Wet_Boots

Supreme Member

Posts: 5,198

Location: Metro NYC

8

Thursday, June 11th 2015, 7:08pm

Okay, SF 1.10 is not so great, but it's better than 1.0
What service factor is, is a way to quantify the "reserve capacity" of a motor. More capacity is better.

Please describe your setup. Are you pumping from a deep well? A well point? Are you just using the pump to boost city water pressure? What voltage is the pump operating at? Does the pump exist on its own exclusive circuit? How much distance between pump and circuit breaker?

Wet_Boots

Supreme Member

Posts: 5,198

Location: Metro NYC

9

Friday, June 12th 2015, 8:29am

The reason for piling up the information is the possibility that the original burned-out pump was an incorrect replacement for a better pump with a smaller (but better) motor. You might also benefit from making a list of the heads and nozzles in the sprinkler system, on a zone by zone basis. From a list like that, you would be able to look on charts and get a good picture of what flow each zone requires, and ultimately match the flow(s) to a proper pump.

10

Friday, June 12th 2015, 2:59pm

The second replacement motor is Exactly the same as the one that came
off the system. I don't know enough to have replaced it with something
different. If I could figure out how to post a picture I'd show you the faceplate.

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