I just had a new house built but my pressure tank is making a knocking sound. I am having a hard time getting my plumber out to solve it so trying to fix it myself. I matched the pressure in the tank to the house pressure, 59psi.
Can someone look at this picture and tell me if this setup looks correct. I still have some fixtures that are not installed but I ran water out of all of these to get any air out. Thanks





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When do you hear the knocking sound? The expansion tank should have some type of support. Is that a swing check valve next to the cold supply ball valve?

I believe you are correct with that being a check valve. The tank is not supported and I will get that corrected. Knocking seems to happen with both cold and hot water, like when a faucet is opened. I have hammer arresters on the washer and dishwasher. The tank was initially only pressured to 40 psi and the knocking was terrible. I matched it to the house @ 59psi and it is much better but still get some. When the hot water circulating pump turns on the knocking seems to disappear.

The knock happens with both the hot and cold faucets and when turning them on(or when turned off?)? Any chance the expansion tank is resting against the wall and bounces against the wall with the change in water pressure?

If it is not the expansion tank banging against the wall I would check the swing check valve.

I have had them bang around on jobs. If it is the check valve you can switch to a spring loaded type.

I will check out these suggestions. Thanks