Pipes Clanking When NO Water is Running

[jjandris]

Hello,

My wife and I moved into a new construction home last April. Since we moved in we have heard clanks of varying tones and loudness throughout the house. The clanks occur when water is running or not (confirmed no water running-even the fridge/ice maker). The clanks occur randomly throughout the day but it seems they are a bit more frequent after the master shower is ran. We have confirmed that the clanks do not just originate from one location and reverberate through the pipes (copper) but originate in many different locations. We did shut off the water and drained all pipes twice. Both times there were no clanks for the 4-6 hours the water was shutoff. They returned when the water was restored. We have not been able to confirm if they are associated with just hot water use. In addition, there is, usually but not always, a knocking (in a consistent single location) that starts off frequently then tappers when we run the master bath shower and/or the master bath sinks.

Our builder had his plumbers open up walls and ceilings to check for loose pipes in several locations but found no issues and added more cushioning. That had no affect. They also added an expansion tank to feed line to the hot water heater. Since when the expansion tank was added in November the pitch of the clanks has dulled and the volume slightly decreased but they are occurring just as much, just as random and still in multiple locations.

These clanks range from annoying to obnoxious and I am concerned they represent a possible structural/functional issue. We are seeking any expert opinions and/or advice on what can be done to end these clanks.

Thanks,

Justin

 

[Mr_David]

Run. . . . . . . . . .

 

[Mr_David]

Just kidding. That's a tough diagnoses from where I'm sitting.
Could be the drains rubbing on the wood as it passes through holes because it to tight.
You say no noise with system drained.
Repeat that test.
After it's all quite for a spell, pour some hot water down the shower drain and see what happens.
Save some before the test and heat it up on the stove.

 

[CT-18]

Could be pressure fluctuation from the main. Do you have a PRV on your main in the house? Could also be thermal expansion at the water heater

 

[jjandris]

Thanks, I will try that to help ID the knocks...now onto the clanks.

 

[jjandris]

If it was pressure fluctuation from the main, could it happen to just my house and not the neighbors? I have talked to them and they do not have the same problems we do. e do not currently have a PRV at the main feed but I am guessing, installing a PRV would not hurt either way, correct?

If its thermal expansion from the hot water tank would putting on a second expansion tank help? Does that possible explain why the pitch and loudness decreased when they installed the first expansion tank? Where should the second be placed?

Thanks for the help.