No load sensor shutting off pump near 50 psi

[Ron Jarrett]

I have a 1 hp 25 gpm pump in a cistern with a franklin no load sensor for 1/2 to 1.5 hp. 20 years old. The no load sensor is shutting off after a minute or so when the pressure tank gets to around 50 psi. Pressure switch is at 35 to 55 psi. Have an 85 gal pressure tank that I think takes about 25 gallons from low to high pressure.

The contact point on the no load sensor is getting black but can't see how that would make it shut the pump down. It takes slightly more than a minute for the pump to fill the tank. For now have bypassed the no load sensor and was going to order a new one. How do I tell if the problem is with the no load sensor or the pump motor?

 

[Valveman]

With the no load sensor bypassed, is the pressure tank filling up and the pump shutting off at 55 PSI? If so then your no load sensor is the problem and you may want to look at replacing it with a Cycle Sensor, seen here. http://cpkits.com/collections/cycle-sensor-pump-monitors/products/cs1ph1-2hp230v

 

[Sponsor]

 

[Ron Jarrett]

With the no load sensor bypassed, is the pressure tank filling up and the pump shutting off at 55 PSI? If so then your no load sensor is the problem and you may want to look at replacing it with a Cycle Sensor, seen here. http://cpkits.com/collections/cycle-sensor-pump-monitors/products/cs1ph1-2hp230v

I suspect that you are right about the no load sensor which does shut off on high load also. I wasn't sure if it was shutting off because the pump motor was taking too much load. I measured current to the one hp 230 volt motor with a meter used for hvac work that I borrowed from a mechanic and neither of us was very familiar with the meter. It did show a current of 9.9 to 9.0 amps which is probably at the high end of the range. Oddly the lower current was at the end of the fill cycle when the pressure is higher. Don't know why the sensor is shutting the pump off, but it is probably the right thing to change first.

 

[Valveman]

Bypass the sensor. See what happens. The motor has a built in overload.

 

[pho]

Whenever we add a device for safeguarding the main element (pump), we get more problem.
You could clean the contact with the spay electrical cleaner since it is a very strong solvent I've do so successfully with my pump contacts point without the pain of replacing the contactor. The contact point shouldn't be hot because the spray is very flammable, an scary incident happening to me few month ago.
Ron and Valveman, please explain to me the benefits of the no load and the cycle control devices which are quite expensive and does it worth ?
List me all the situation where such cases happen ? Does the cycle control is activated immediately for the 1 st start stop of the pump ?

 

[Ron Jarrett]

Whenever we add a device for safeguarding the main element (pump), we get more problem.
You could clean the contact with the spay electrical cleaner since it is a very strong solvent I've do so successfully with my pump contacts point without the pain of replacing the contactor. The contact point shouldn't be hot because the spray is very flammable, an scary incident happening to me few month ago.
Ron and Valveman, please explain to me the benefits of the no load and the cycle control devices which are quite expensive and does it worth ?
List me all the situation where such cases happen ? Does the cycle control is activated immediately for the 1 st start stop of the pump ?

Whenever we add a device for safeguarding the main element (pump), we get more problem.
You could clean the contact with the spay electrical cleaner since it is a very strong solvent I've do so successfully with my pump contacts point without the pain of replacing the contactor. The contact point shouldn't be hot because the spray is very flammable, an scary incident happening to me few month ago.
Ron and Valveman, please explain to me the benefits of the no load and the cycle control devices which are quite expensive and does it worth ?
List me all the situation where such cases happen ? Does the cycle control is activated immediately for the 1 st start stop of the pump ?

I have had both my well and the holding tank it pumps into run out of water for various reasons. I think the no load shut off might prevent a pump failure under these conditions. I left a valve closed once and the overload shut it off, but if it hadn't , the circuit breaker probably would have shut it down.

 

[Valveman]

You do not want to rely on the overload to shut the pump off when the well is dry. Overload happens way too late. The fact that the amps rise when the pressure increases is indicative of a bad thrust bearing in the motor. So the sensor maybe shutting off on high amperage instead of low amperage as happens when the pump is full of air instead of water.

Ron and Valveman, please explain to me the benefits of the no load and the cycle control devices which are quite expensive and does it worth ?
List me all the situation where such cases happen ? Does the cycle control is activated immediately for the 1 st start stop of the pump ?

A low load sensor like the Cycle Sensor looks for low amps that happen when the well is pumped dry. It looks at low amps for about 5 seconds before it shuts off the pump. Then it has a built-in timer that can be set from 1 to 500 minutes for the pump to restart. If you pump the well dry and the Cycle Sensor shuts off the pump before anything is damaged, the Cycle Sensor already paid for itself.

A cycle control devise like a Cycle Stop Valve varies the amount of flow from the pump to match the usage. This way there is no extra water produced to fill the tank and cause the pump to continue to cycle on and off, which is bad for the pump/motor. Without a CSV the pump is always producing max flow, and if you are using anything less than max flow, the pump continues to cycle on and off repeatedly, which again is a bad thing.