Rattling in pipes from thermal expansion?

[doneil13]

Hi all,

Total amateur here.

When we run the hot water in our spare bathroom sink I can hear this ticking or rattling in the wall. After turning the water off, it continues for a few moments and then slows and stops. When we run the hot water in the shower/tub I can hear it in the ceiling in the room next to the bathroom and it continues periodically (non-continuous) for a while after. For context, we are on a single floor range and all the plumbing runs through the attic.

We had our plumber come out and take a look. He said the noise was from thermal expansion in the pipes; and potentially because the pipes (PVC i believe) might not have been properly secured on installation. He lowered the temp on our water heater down to the industry standard as it was a little high. He checked the water pressure and said it fell within the normal range.

He said if we didn't see any improvement in a week or two then the next step would be to add an expansion tank to the water heater to help solve the thermal expansion in the pipes.

It's been a couple of weeks and no improvement.

So two questions from me:

1) is it possible that thermal expansion is causing this noise?
2) would an expansion tank help to solve this? My understanding was an expansion tank was designed to help with the thermal expansion of the water heater, not the pipes.

thanks in advance!

 

[Twowaxhack]

Nothing you do will alleviate your problem except ripping open the walls and ceiling and finding where they drilled the holes too small or have pinched the pipe between building materials. It can be water pipe and drain pipe.

When the pipe heats up ( drain or water or both ) it expands against other building materials.

If you have thermal expansion in the system that will cause your pressure to rise, it will not cause noise during flow conditions.

A thermal expansion tank willl not solve a noise problem due to holes being drilled too small for the size pipe or other building materials touching and rubbing.

 

[doneil13]

Nothing you do will alleviate your problem except ripping open the walls and ceiling and finding where they drilled the holes too small or have pinched the pipe between building materials. It can be water pipe and drain pipe.

When the pipe heats up ( drain or water or both ) it expands against other building materials.

thx! got it; any concerns with leaving how it is if we can live with the noise?

 

[Twowaxhack]

thx! got it; any concerns with leaving how it is if we can live with the noise?

If you have thermal expansion due to the water heater heating and expanding the water then it needs to be controlled. But that’s got nothing to do with pipes rubbing when they expand.

I wouldn’t worry about the rubbing when you turn the hot water on.