How can a New Jet Pump Cause Pressure Switch Problems?

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Texas Wellman

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Is there a regulator or check valve between the pump and tank?

If possible try to run your pump on 230v. Switches these days are much more prone to failure on 120v.
 

Doug V.

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Your pump is running on 240 ("230").

Ideally the pressure switch would have been mounted "closer" to the pressure tank. The symptom not having a close enough connection would be to turn off early or some such. Your symptom about starting the pump by pushing the contacts is not caused by that however.

If you had not already replaced the pressure switch a few times, then we would expect a bad pressure switch. So now, get the multimeter. Numbering the switch terminals 1, 2 , 3 , 4, then the voltage between 1 and 4 will be about 240 volts plus or minus maybe 10%. That should be about the same whether the pump is running or not.

When the switch is closed (on) the voltage 1 to 2 should be less than a volt. Same for 3 to 4. If this is found not to be the case, you have a third bad pressure switch.

Also, you want to read up on setting and checking the air precharge.
 

Doug V.

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I am burning up pressure switches. And I can't seem to be able to find a pressure switch rated for my water pump. I have a 5HP downhole pump, and it runs on 240 volt, AND it is SINGLE phase. Does anyone know where I can get a pressure switch rated for this service? I've seen 5HP switches, but they were either 460 volt, OR they were 3-phase. Can't find single phase 240 volt.
 

Reach4

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I am burning up pressure switches. And I can't seem to be able to find a pressure switch rated for my water pump. I have a 5HP downhole pump, and it runs on 240 volt, AND it is SINGLE phase. Does anyone know where I can get a pressure switch rated for this service? I've seen 5HP switches, but they were either 460 volt, OR they were 3-phase. Can't find single phase 240 volt.
I think many 5HP control boxes have a relay to control the pump, and that relay gets controlled by the pressure switch. Check to see if your box has that.

You can use a 3-phase switch for 2 pole single phase switch. Just use one contact unused. There may well be exactly what you are looking for.

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Valveman

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Yeah you should have started a new thread. But there are no pressure switches rated for 5HP. You need a definite purpose contactor or magnetic starter. They make 5HP control boxes that already have a contactor, they are called "deluxe" control boxes. With a "deluxe box the pressure switch only sees enough amperage to run the coil in the contactor, and the big points in the contactor handles the 5HP amperage.
 

mnocket

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Update to original thread

Still working the problem about the pressure switch appearing to close but the jet pump not starting. I have new information and would appreciate your comments....
  • I originally thought that the switch contacts were not completely closing. I was wrong. They are closing but the pump sporadically doesn't start
  • There is 120V to the switch and (although unnecessary) both the hot and neutral lines run through the switch. Here's the interesting part.... the contacts on the hot side are oxidizing VERY quickly. I've attached a picture - this switch is only a little over a month old. Neutral side looks OK but hot side is severely oxidized.
  • Now most interesting of all! It seems that the sporadic nature of the problem is because the problem occurs when the well pump is already running and then the jet pump tries to start. In this instance the switch contact close, but due to the oxidation on the hot contacts the jet pump doesn't start (verified with multi meter). I don't why this doesn't occur at other times, but the oxidation seems to only cause a problem when both well and jet pumps try to run at the same time.
  • Both the well (240V) and jet (120V) pumps are on the same circuit. The breaker never trips.
So, there seems to be two related problems.
1. The switch contacts on the hot side are oxidizing very quickly causing intermittent failure of the jet pump to start.
2. The problem occurs when both the well and jet pumps try to run at the same time.

I've attached a pic of the jet pump label. It only shows a max amp value. How much current should this pump be drawing? Could the pump be drawing too much current and causing the contacts to oxidize and somehow causing the problem when both well and jet pumps are running?
Thanks
 

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Valveman

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I don't think that is oxidation. It looks like arcing damage. The higher the amperage the more arcing. When both pump run on the same circuit the voltage is reduced, so the amperage increases, which causes more arcing. Arcing should only happen when the contacts open or close, not when running. Usually it is the number of times the pump is cycling that causes the problem more than the current.
 

Reach4

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Both the well (240V) and jet (120V) pumps are on the same circuit. The breaker never trips.
That is unusual.
How many amps is that breaker?

I presume the switch wiring photo is for the (20180609_151204_resized-jpg )

You might want to rewire the jet pump to 240 volts as suggested by Texas Wellman. That would cut the current through the pressure switch contacts in half. If you keep 12o volts, you might wire the contacts in parallel. That way each contact will carry some of the current. The current sharing will not be 50/50, but it will be something.

Also, does your jet pump have a start capacitor?
 
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mnocket

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http://www.sta-rite.com/resources/images/1119.pdf is your manual. Page 8 shows how to change the motor voltage. Of course you have to wire the power to the motor too.
Thanks. I agree this is the next step, but I wonder if there is something wrong with the pump motor. This whole problem began when I had the jet pump replaced (both were 1hp, 120V). I ordered a clamp meter so that I can measure the current draw by the motor, but I don't know what value I should be looking for. Any idea what a 1hp, 120V motor should draw? If there's a problem with the pump motor I'd like to have the installer replace it (and wire to 240V) instead of masking the problem by converting a bad motor to 240V. I don't know if there's a start capacitor or how to tell if its faulty. There's no large cylindrical attachment on the exterior of the motor, which is what I associate with a start capacitor, but otherwise I don't know.
 
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Reach4

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Any idea what a 1hp, 120V motor should draw?
About 15 amps once running. Maybe 2 or 3 times that during the start.
If there's a problem with the pump motor I'd like to have the installer replace it (and wire to 240V) instead of masking the problem by converting a bad motor to 240V.
You probably should have run a separate circuit for each pump. During the failed starts, you might find that your voltage to the pump has dropped below 108.
 

mnocket

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About 15 amps once running. Maybe 2 or 3 times that during the start.

You probably should have run a separate circuit for each pump. During the failed starts, you might find that your voltage to the pump has dropped below 108.
What happens if the voltage drops below 108v? Does some protection circuit in the motor switch off?
 

Reach4

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What happens if the voltage drops below 108v? Does some protection circuit in the motor switch off?
108 is 120 minus 10%. I don't know where the actual voltage is that cause a problem. How low does your voltage go? That seems like an easy-enough thing to measure. Whatever it drops to, it will be a lower percent drop when you rewire for 240 volts.
 

Splat

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I would also check those crimp connectors and the wire gauge used. They appear to be bent in your pics, which if they are will fatigue them. So check that and the motor. I've gotten bad new motors before.
 
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