I have just noticed my water pump has developed a hammer when it stops. Ie. hydraulic shock.
I there usually an integral check valve? The pump is under the stairs in a dark area so not easy to see. If there is one it could be sticking and I'll have to take it out and clean it. I can't see one in the inlet or outlet blue piping.
Subsequent edit.
Grovelled under there and found a piece of gravel in the check valve. Now the question is should there be a spring? because mine doesn't have one.Ok found this from another thread
If so the check valve in the water pump may not be working properly, allowing water to run back into the tank leaving air in the impeller. Remove the plastic cap your fat finger is pointing at. You will see a plunger like plastic valve with a spring. Pull it out and check to see if the rubber gasket and where it seats is clean. Also, make sure the spring is functioning.