Water pump going on and off


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Old 12-16-14, 03:57 PM
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Water pump going on and off

I'm a retired American living in Thailand. I have a well pump that fills 2 large water tanks on top of the pump house. From them a pipe leads to another pump just underneath it. When I turn on the water the tank cycles on and off causing the water to pulse. This seems to happen every few days. I turn off everything and drain the little tank on the water pump. Then turn everything back on and things work fine for another few days then it starts to do the same thing all over again. Any ideas? Thanks
 
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Old 12-16-14, 05:18 PM
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Welcome to the forums.

That little tank on the water pump sounds like a pressure tank that isn't holding an air charge. Since water can't be easily compressed .... a pressure tank with air in it is used to provide a cushion for the water pressure.

No air = no cushion = pump short cycling.
 
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Old 12-17-14, 05:05 AM
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Is the "little tank" a steel tank? Is there a Schrader fitting (like on a car or bicycle tire) on the tank? If so then PJmax is probably correct. The air in that tank should be set to be 2-3 psi less than the pump's cut in (turn on) pressure.

Most pressure tanks have a rubber bladder or diaphragm that keeps the air and water separate. If your diaphragm has ruptured then the air, under pressure slowly gets forced into the water and carried away. After a while you are left with little or no air left in the tank and need to drain it to get air back inside.
 
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Old 12-17-14, 05:43 AM
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Which of the two water pumps is cycling on and off rapidly?
 
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Old 12-17-14, 07:57 AM
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"Most pressure tanks have a rubber bladder or diaphragm . . . "

Mmmm. That's not been my observation in lesser developed countries.
 
 

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