Banging/machine gun sound for a few seconds after turning on tub faucet

[miketp]

I have a mystery issue with my shower that I'm hoping someone can help solve. When I turn on the Delta tub faucet, everything works as expected. However, if I use the faucet again shortly afterward (within say an hour), a loud banging/machine gun sound occurs after about 5 seconds and lasts for another 10-20 seconds before stopping. If I change the temperature while it's banging, the banging temporarily stops. This problem only started after I put spray foam insulation into the wall where the pipes are located. At first it was a squealing sound, but after I replaced the cartridge, it became a banging/machine gun sound. I thought it could be water hammer, but I drained the pipes and refilled to no avail. This has been happening for months.

Any ideas?

 

[Smooky]

It could be caused by a partially closed valve or other restriction.

 

[Sponsor]

 

[MKS]

"This problem only started after I put spray foam insulation into the wall where the pipes are located."
Sticky stuff, pipes maybe expanding and contracting in it making noises.

 

[Erico]

I have a mystery issue with my shower that I'm hoping someone can help solve. When I turn on the Delta tub faucet, everything works as expected. However, if I use the faucet again shortly afterward (within say an hour), a loud banging/machine gun sound occurs after about 5 seconds and lasts for another 10-20 seconds before stopping. If I change the temperature while it's banging, the banging temporarily stops. This problem only started after I put spray foam insulation into the wall where the pipes are located. At first it was a squealing sound, but after I replaced the cartridge, it became a banging/machine gun sound. I thought it could be water hammer, but I drained the pipes and refilled to no avail. This has been happening for months.

Any ideas?

Did you have the water off at the shut-offs on the valve? I had a similar problem and it was because I didn't have the shut off all the way back open on one side.

It could be a blockage on one side if not the valve.

 

[Reach4]

are not pitched properly therefore not allowing
the water to drain properly it happened to me this company

I call fake.

 

[FullySprinklered]

And, the golden pipe wrench award goes to: Master Plumber! Y'all excuse me, I've got to run down to the basement and repitch my pipes.

 

[WJcandee]

I am waiting for Master Plumber to come back and say that the problem is that the hot and cold water lines are not properly vented, and that if you go to his referral web site for Wayne, NJ, he can find you a plumber to make sure that the hot and cold water lines are properly vented through the roof.

(Just so Miketp isn't confused: if someone told you this it would also be total BS.)

Mike, I'm thinking that you closed a valve somewhere in your system at some point and didn't reopen it all the way. The whining and the cavitation (banging) are two things that can happen where an upstream valve isn't all the way open. It also could be caused by improper installation of your new cartridge.

 

[miketp]

So I checked all of my valves and they're all fully open, so I don't think that's the issue. The sound stops when I pull up the diverter and the water just comes out of the shower head. Also when I took off the tub spout, I noticed the water pressure isn't consistent. See the attached videos for details.

Any other ideas?

https://vid.me/v2L5
https://vid.me/lalb