Water hammer and pipe noise when pump cuts off

[Tim Leiter]

Tim Leiter New Member
Joined:
Saturday
Location:
pennsylvania
I'm having a hard time finding the cause of water hammer and pipes shaking when pump cuts off. Pressure in holding tank good at 28 psi. Pulled the pump up to pit less adapter to check if it was holding water, so that check valve is good down at the pump. Replaced the check valve right before the holding tank and it made no difference. I do have a gauge right inside the house where the line comes in. The gauge will read accurately to pressure tank gauge when the pump is running and when it cuts off the gauge goes to 0 for a few seconds and then starts creeping up to about 12-15 psi with no pump running in about 20 seconds. It does not loose pressure sitting idle, so I don't think I have a leak underground. The pressure switch at the tank is set to 30/50.

 

[LLigetfa]

Replaced the check valve right before the holding tank and it made no difference.

I suggest removing it since it would not be a part of an airmaker snifter/bleeder/check. The only check valve you should have is at the bottom of the well.

 

[Sponsor]

 

[Valveman]

The check valve on the pump maybe holding, but it is sticking in the open position. Remove the above ground check valve and see if that helps. But you may need to replace the bottom check on the pump if it is still sticky. BTW, check valves wear our and start sticking because they slammed closed too many times from cycling the pump on/off way too many times.

It might also help to add a Cycle Stop Valve. They usually go in place of the above ground check valve anyway. The CSV will reduce the flow to 1 GPM before the pump shuts off. This might give the sticky check valve time to close to 1 GPM before the pump shuts off. Even if you still have to replace the bottom check, the CSV will stop the cycling and keep it from happening again.

 

[Tim Leiter]

Does anyone think I might have a leak in my line from the well to the house because the pressure gauge right inside the house goes to 0 psi for about 5 seconds before it creeps up to about 12 psi after a minute?

 

[Reach4]

Does anyone think I might have a leak in my line from the well to the house because the pressure gauge right inside the house goes to 0 psi for about 5 seconds before it creeps up to about 12 psi after a minute?

I cannot explain the behavior. I don't think a leak explains it.

 

[Valveman]

Could very well have a leak. The water hammer you are hearing is causing pressure spikes 10 times higher than the pressure on the gauge. With water hammer spikes of 500+ PSI you could have pin hole leaks starting everywhere. But I don't think you have a leak now. If you had a leak, water below the above ground check valve would leak back. Then when the pump starts it would push a pipe full of air into the system which would be blowing your toothbrush out of your hand. No air, no leak.

But it does confirm that your bottom check is leaking back. The topside check valve is also leaking back, as that is where the 12 PSI is coming from. Either the check is only leaking back to 12 PSI, or it is leaking slightly less than the bottom check, and the pressure is maintained at 12 PSI until the tank is empty and the pump starts.

Again, remove the top check valve. If the pressure holds overnight, you don't have a leak and the bottom check is holding. If it doesn't hold pressure overnight, you will need to fix the bottom check. Every time you hear that water hammer the bottom check just slammed shut with tremendous force. You will be very lucky if you don' t have to pull the pump and replace that check valve. And remember the two things that caused your problem are having too many check valves and cycling the pump too much.