Copper Pipes excessive noise

[DIYorBust]

So I had two delta 1/2 inch thermostatic valves installed, they are fed with 3/4 inch copper rough reduced a few feet from the valve, from a 3/4 inch riser. Each has a tub spout with a shower diverter. One is on the 2nd floor and one is on the 3rd floor. When the tub is filled on the 2nd floor, the riser is very loud, and creats a loud hiss on the 2nd floor. The same configuration produces almost no noise on the third floor. When the shower is running there is no noise.

Any ideas how to troubleshoot this?

Thanks!

DIY

 

[Jeff H Young]

Something is different between floor 2 and 3 the height and length of run aren't that big a difference. Cast iron tub on 3 and flimsy fiberglass on 2 ?

 

[Sponsor]

 

[DIYorBust]

something is differant between floor 2 and 3 the height and length of run arent that big a differance. Cast iron tub on 3 and flimsy fiberglas on 2 ?

Other way around, cast iron on 2 and flimsy on 3. I tried filling a bucket while holding it, the noise seems to be from the flow in the pipes rather than the water hitting the tub.

 

[Jeff H Young]

Other way around, cast iron on 2 and flimsy on 3. I tried filling a bucket while holding it, the noise seems to be from the flow in the pipes rather than the water hitting the tub.

OK that's what I would do as well. you've got 3/4 going all the way upstairs to just before the valve as well? maybe flow reduces enough to be quieter

 

[DIYorBust]

OK that's what I would do as well. you've got 3/4 going all the way upstairs to just before the valve as well? maybe flow reduces enough to be quieter

Thanks, yes I have 3/4 going all the way to the cellar, where it connects to a 1 inch back to the meter. I'm thinking the plumber maybe has too many bends in the shower hookup, but I want to explore any other possibilities before I open the wall. What else can I check?

 

[Jadnashua]

Check the water pressure. Higher pressure will cause the water to flow faster in the pipes. The Copper Institute has defined some maximum water velocity specifications for hot and cold copper pipes. For hot, the maximum velocity is 5fps, which is only 4gpm with a 1/2" line, and 8gpm on a 3/4" line. Water speeds up when it hits a restriction (but that also creates more friction). Static water pressure drops about 0.4#/foot elevation, so the pipes on the third floor will have less pressure, but not all that much (maybe a couple of pounds or a bit more). On cold pipes, they allow the water to flow faster, I think it's 8fps. Excessive velocity can cause water flow noises, and maybe more critical, actual erosion of the pipe from the inside.

If your static water pressure is >80psi, you need a pressure reduction valve and an expansion tank since the PRV will create a closed system, and heated water needs a place to expand that it could (likely) do into the supply prior to the addition of a PRV. Dynamic pressure will vary depending on the length and diameter of the pipes, the velocity, and the number of elbows/tees/etc. in the system.

It could be just that they didn't anchor the pipes well, but that is harder to check...check the pressure first.

 

[Jeff H Young]

good thing to check the pressure. Jadnashua good call

 

[DIYorBust]

Just got back to work on this, I checked the pressure at a tap near the water service line in the cellar and found it to be 55psi. Any ideas what to try next? Could it be the delta t17 valves?

 

[WorthFlorida]

As jadnashua mentioned, it's all in the velocity. I grew up on Long Island with copper pipes, my homes in Illinois and Florida with copper pipes all made a fair amount of noise when the tub spout was in use and quiet down when it switched to shower. And I remember many times hearing that hiss just before full flow to the shower head. At the noisy tub, remove the cartridge and check for debris. Sometimes after soldering there could be pieces of solder balls that were inside the pipes and may get jammed up somewhere. If there are any shut off valves before the tub, check those.

For the pressure check you need to leave it on for a day, overnight preferred, and with the tattle tail needle it will give you the range of pressure. Since LI has almost all water towers the pressure will remain quite the same most of the time, but as the water is heated up there will be expansion. If you have a spigot on the pipe leading to the upper floors that may be used for draining, place the gauge there and run the water to get a read on the pressure.