shower valve oscillation

[dca]

Hello - I had an old Delta crystal ball style shower faucet/valve replaced with a Pfister Rancho by a local independent plumber.

This is in a 2nd bath that is back to back with the master bath. Seemed like he did a decent job, but now when the 2nd bath shower is in use, and the toilet is flushed in the master bath, the pipes in the wall oscillate until the toilet valve shuts off. It may also happen to a lesser extent when both showers are in use.

I'm attaching pictures - can someone advise if the plumber did anything suspect, or if it is a function of only the Pfister mixing valve itself + pressure drop. I assume the Pfister has to be causing the oscillation, just not sure why a drop in pressure triggers it.

I see where the middle pipe is shimmed in a haphazard way. Maybe if I dampen the other pipes, it may minimize the sound, but not a true fix.

I called Pfister and their LCC support of course said it couldn't be the valve and had to be the house (but it didn't do this before). I asked if I could send them pictures, just to verify that part was done properly to their installation expectations, and they said No. Great customer support these days!

So, please advise and thank you in advance!

DCA

 

[Twowaxhack]

What’s your water pressure ?

 

[dca]

I have not checked the pressure. It does not seem low. I considered reducing the flow to the adjacent toilet and seeing if that helps, but it's more of a workaround than solution.

One thing to note is that in this house, they used a main trunk of copper pipe with a larger diameter cold water and smaller diameter hot water pipe. Then the feeds that go to the bathrooms are taken off the main trunk in the same diameter about 10-15' apart from each other in the basement before running upstairs.

 

[Twowaxhack]

Check your water pressure. It may be too high.

Your description of when the problem occurs points to high pressure in general.

The toilet ballcock may be malfunctioning. Take lid off snd snap a pic of tank parts. Make sure the water valve is all the way open to the toilet.

 

[Twowaxhack]

You could have a pressure reducing valve failing.

 

[dca]

ok, the toilet ballcock is full open.
That was where I thought closing it halfway or so may help.

Picture of tank valve attached. It's a generic toilet, about 5-7 years old.

Where would a pressure reducing valve that's potentially failing be located?
- I don't think I have one.

Thanks

 

[Twowaxhack]

Anywhere from buried in the yard outside to in a basement, etc.

Get a pressure gauge and check your water pressure. It should be 80 psi or less.

 

[dca]

OK, I'll try to check pressure. Would something like this connected to hose bib work?:
Watts 0950200 (pic attached)

No pressure reg valve in house, just meter and piping.

 

[TomFOhio]

That guage will work. I think twowax has it figured out. Replace the gasket on the top of that flush valve. If that doesn't
help then replace the flush valve with a new one. You plumber did you a nice job. That piece of wood is just holding the
tub sprout to the wall tighter.

 

[dca]

Thanks TwoWax and Tom for your responses. Thanks for the validation of the plumber's work, just so I know it's good.

I can check the toilet valve, but I think the other shower being on triggers it too.

So, if I find I have more than 80 PSI, I'm not clear on what the solution would be. Regulating it down, or play with the shutoff valves' open % to try to reduce the chatter?

I could try this, even without knowing the pressure - but for $10 is a handy tool to have anyway.

So, how does the toilet valve come into play? It is not during opening and closing, but during full open operation of both fixtures.

Thanks again for the ideas. I'm going to try some experimenting tonight with the shutoff valves to see if that helps.

DCA

 

[TomFOhio]

Does it chatter with just the two showers running at the same time without flushing the toilet.

 

[dca]

Does it chatter with just the two showers running at the same time without flushing the toilet.

Tom - Yes, just not as bad.

 

[TomFOhio]

So your pipes rattle some with the showers on? There must be a loose pipe someplace. Run them and get in the back
of them and feel the pipes.

 

[dca]

That may help dampen it, but I think it's related to the anti-scald H-C balancing in the new valve. I'm going to check the instructions, but there may be an adjustment for it in the fixture. Otherwise, I'm going to see if the flow/pressure adjust between fixtures might help. Thx for the help.

 

[Twowaxhack]

So what is your water pressure ?