water hammer at pump, Help!

I recently took my pump from under the house into the garage by adding pvc to the black poly going out to the well. I have a check valve right before the pipe goes into tthe pump. The hammer is only in the main line going to the pump. You hear it when the pump cuts off. Sounds like a loud thud. How can I stop this? What could be causing it?

You shouldn't have a check valve on a jet pump except for the foot valve. If I'm understanding you correctly, you have a leaking line or foot valve and the check at the pump is masking the problem. Sometimes a makeshift 'fix' to a leaking foot valve is to add a check at the pump but, that can cause hammer and other problems. Fixing the leak from the pump to the foot valve or replacing the foot valve is the only true 'fix'.

Gary
Quality Water Associates

I agree with Gary, and I wonder what kind of check valve you have at the pump. It sounds like a swing check used for sewage and sump systems. These can really do some hammering since they are not spring loaded and canbe totally open until the pump stops. Then wham!

bob...