# Hissing from shower valve



## pbechard (Oct 6, 2010)

I replaced a shower valve on the second floor. This new valve *only makes a hissing sound* when the 1st floor toilet is flushed. I have tried running other faucets in the house and these faucets have no effect on the new shower valve. 

The valve in Moen, I plumbed in with pex with Sharkbit fittings. 

Thanks for any and all feedback!:clap:


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## DemRem (Apr 21, 2012)

This is just a guess but I'd say that when the toilet flushes it begins to draw cold water changing the flow rate slightly at the fixture. That change could be the exact amount necessary to produce the hissing/whistling sound. Similar to whistling with your lips...too much or too little air makes no sound but the right amount does make a sound (something about ideal frequency or some jazz...if I remember my physics right)

Anyway, as far as fixing it (assuming it is a flow issue) you could try actual pex to copper or whatever fittings. They might change the dynamics in a way that would prevent the hiss. But I would do that anyway if I was you. I've never felt comfortable with sharkbites.

PS this is just a guess there's a lot of people on here that have decades of plumbing experience and I would try and get their take on it.


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## underwoodhi (Feb 14, 2013)

DemRem said:


> This is just a guess but I'd say that when the toilet flushes it begins to draw cold water changing the flow rate slightly at the fixture. That change could be the exact amount necessary to produce the hissing/whistling sound. Similar to whistling with your lips...too much or too little air makes no sound but the right amount does make a sound (something about ideal frequency or some jazz...if I remember my physics right)
> 
> Anyway, as far as fixing it (assuming it is a flow issue) you could try actual pex to copper or whatever fittings. They might change the dynamics in a way that would prevent the hiss. But I would do that anyway if I was you. I've never felt comfortable with sharkbites.
> 
> PS this is just a guess there's a lot of people on here that have decades of plumbing experience and I would try and get their take on it.


Sounds reasonable, and if so you could slow the flow to the toilet by closing the supply valve a bit.
maybe!


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