What could cause the sump pump to cycle on and off rapidly

sump-pump

I have a new condition with my sump pump. It runs for a few minutes (like normal) and then it stops for a few seconds and runs for a few seconds over and over (maybe 10 times). This happens every time the sump pump runs. It has been doing this for the last couple months and I'm concerned that this is causing additional wear on the pump. I installed a battery backup pump on the same outbound pipe last fall, but it has been running fine with that install for many months.

Any ideas on the cause or how to narrow down the cause?

Best Answer

I'm not a sump pump expert, but it sounds like perhaps your check valve isn't working properly. If it isn't closing fully then water in the pipe can drain back down into the sump when the pump stops. If enough water is able to drain back down then it would cause the pump to start again.

Assuming you actually have a check valve, it probably looks something like this:

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The lower the check valve is installed, the less water will be able to drain back down.