fog horn pipes

Hope someone can help. Three weeks ago I installed an expansion tank on my water line after my prv and befor my hot water tank. The tank is a watts tank which I calculated on their web site as the proper size for my system.

I am on city water incoming pressure at about 100-110psi. It is reduced down to 60 psi with my prv. The tank pressure is set at 60psi which is the same as the prv. I had no problem for three weeks and now all of the sudden after the system sets overnight undisturbed, when a faucet is turned on I have a fog horn sound in the entire house. Sound will go away for a short period of time such as taking a shower. However within a matter of minutes the sound will come back.

The reason for the expansion tank install was because I noticed an excessive amount of air in the lines after the system would set overnight. I am concerned the expansion tank is the cause, but why did it work fine for three weeks and the sound just start up now.

Any help would be apprecitated

Thanks

Dave

Air in lines?
There is no way for air to get into the water lines.

Have you turned off and drained the water and rechecked the pressure in the expansion tank?

try isolating the toilets by turning off the angle stops and see what happens. sometimes a failing fill valve will cause this.

I will give it a try. Thanks for the help

Air in the lines would indicate someone worked on the water line near by and I am going to guess there is debris in the PRV. The next time you hear the noise go near the PRV and listen and see if it isn't the PRV.

I listened to it this morning and it appeared the prv might have been vibrating. If it is the prv, what is the fix. Replace or take apart and clean. The prv is only 4 years old.

You can try taking it apart and cleaning the surfaces or just go out and buy another and replace it. They do have rebuilding kits but not all places carry them.

I find it is just as easy to replace them.

1 Note if your water meter is right near it, it is possible that the meter is creating the sound and it seems to be coming from the PRV.