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  #1  
Old 09-23-2009, 10:21 AM
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mx315 mx315 is offline
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Pump temperature?

I had a call Friday from a guy that wanted some heads moved. I went by to take a look and he gives me the rundown of what he wants done... no big deal, except his front yard has 14 heads (7 rotors & 7 sprays) running on a 1hp pump. The last guy to work on it has the pressure switch cranked down so the system is operating at 78 lbs and cutting out at about 85. The pump is so hot that you could fry an egg on it. I told him that I would make some changes and see if I could get the pressure down, so the pump wasn't working as hard. I got it down to a operating pressure of about 62 and cutting out around 70. That's all I could get it to down to without cycling. I went by this morning to check it out and the pump still seems to be running really hot. I told him the best option would be to split front zone and add some of it to a small zone from the side of the house. But my main question is, How Hot is too hot? What temp range should it be running in, so it doesn't damage the pump?
thanks
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Old 09-23-2009, 10:38 AM
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I sure hope this isn't a single-stage pump.
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  #3  
Old 09-23-2009, 10:42 AM
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mx315 mx315 is offline
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Yep, 1hp Sta-rite jet
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Old 09-23-2009, 10:53 AM
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I would want a 1 hp jet to be running in the 40-50 psi range, give or take. Thing is, if the outflow increases to lower the output pressure, the pump is working harder to lift more water. What happens if you manually open two zones? Can the pump run without cavitation if it delivers more water?
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Old 09-23-2009, 11:32 AM
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He has one zone in the back with 4 rotors, but somebody wired it to run with one drip zone in the front to keep it from cycling. He has another back zone with 8 sprays and has it wired to run with a different drip zone. They are running fine together, but you can tell that it's running high pressure. The drip line is doing alot more than dripping! I've listened to the pump and don't hear any cavitation, only short cycling issues because of the big difference in zone sizes.
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Old 09-23-2009, 11:37 AM
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I'm talking about cavitation with two zones running. I wonder if this pump was a replacement for a smaller one, with the kind of imbalance you describe.
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  #7  
Old 09-23-2009, 01:02 PM
hamham hamham is offline
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Is it the motor or the volute that is hot?
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Old 09-23-2009, 01:42 PM
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Boots, It's just a really bad install job... he's had problems since day one. I didn't run two of the main zones by themselves, I will when I go by this afternoon.
It looks like he's been trying to work on it too. I saw alot of irrigation parts in the garage when I was checking out the controller.

Ham, The motor is getting hot. It's so hot you can't lay your hand on it for more than a second or two.
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Old 09-23-2009, 01:47 PM
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Sounds like there would be some point in considering a smaller pump. Or a complete re-nozzling.
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Old 09-23-2009, 03:25 PM
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I think I'm going to work on splitting that front zone and tying it into the smaller one, then see if I can get the pressure down to normal.
Thanks for the input
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