Pipes in wellhouse thumping after shutoff

[Frog2000]

I noticed the pipes in my well house will start shaking after the well pump turns off. When the pump turns off the pipes will shake for a few minuets. Eventually after maybe 10 minuets it will eventually settle.

I checked the pressure tank and it's at 28PSI. I also checked for leaks and found no significant leak. 2psi drop after 90 minuets and even if I shut off the line to the house I still get the shaking. I tried turning the pump off during the shaking and this has no affect. The only way to stop the shaking is to wait it out or turn the pump back on. I would have already pulled the pump to inspect but the pump is 290 feet down.

I have added a video of the shaking. What is going on here and how do I fix it?

 

[Reach4]

Weird. What is the pipe to the left that does the shaking?

 

[Sponsor]

 

[Frog2000]

Weird. What is the pipe to the left that does the shaking?

Just some more pipe, it's PVC. I talked to one well guy and he seemed pretty confident that a check value would help. Any recommendation on what kind of check value to look for? Will any work?

 

[Reach4]

Is that pipe to the house or from the well?

An above-ground check valve is usually a bad idea, but who knows in the face of your extraordinary symptom.
I see you are using a Mac.

"2psi drop after 90 minuets
I presumed that pressure drop was within the first several seconds. Does that pressure drop continue after a minute? If so, an above ground check valve could work around a down-hole problem.

 

[Frog2000]

I installed the valve and with the pipes open I could hear gurgling towards the well side. Needless to say the value didn't really help. the pipes above ground stopped shaking but I could still hear the water behind the value swashing back and forth.

 

[Bannerman]

the pressure tank and it's at 28PSI. I also checked for leaks and found no significant leak. 2psi drop after 90 minuets

Your description is not clear.

I understand from the video, the pressure switch is configured @ 30/50 psi. Is the 2 psi drop after 90 minutes mentioned above, referring to the system pressure dropping from 50 psi to 48 psi after 90 minutes, or are you referring to a pressure tank pre-charge loss from 28 psi down to 26 psi?

Based on the video, I suspect the check-valve within the pump is not fully closing which is allowing the water stored within the pressure tank to be forced back down through the pump's check valve back into the well. The rapid backwards flow maybe causing the check-valve gate to flutter, resulting in the pipe shaking due to rapid changes in flow through the fluttering check-valve gate. If this is the situation, I expect the system pressure will continually drop from 50 to 30 psi whereby the pump will become reactivated to raise the pressure backup to 60 whereby the situation will be repeated again.

Adding an above ground check-valve may mask the symptom temporarily, but the correct remedy will be to pull the pump to repair/replace the existing check-valve or add a new in-line spring loaded check valve directly at the output connection on the pump.

 

[Valveman]

As was said, the check valve on the pump is bad. Adding another check valve up top will help some as you have seen, but water is still slipping through the check on the pump, which makes it bounce and hammer. You will need to replace the check on the pump and remove any other checks like the one you just added. Check valves fail from slamming closed so many times when the pump is cycling on and off. Adding a Cycle Stop Valve will solve that problem as well as many others and give strong constant pressure to the house.

 

[Frog2000]

following up for the next guy. Not exactly sure what came first but there was a crack in the line in the well and the pump was suck in the sand. This was on top of the bad check value. Ended up getting a whole new well and pump.