Valves in PEX system


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Old 07-29-16, 06:48 AM
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Valves in PEX system

I have seen the manifolds and other ways of distribution in PEX systems but one things that makes me wonder (PEX or no PEX).... rather than having one central distribution system...why not simply put single valve as the piping enters each "zone" / bathroom
Assuming of course full access...like when pipes are accessible from the basement....would there be any performance hit to just place valves before each branch rather than locate all valves in once central place by the main water entry?

thanks!
 
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Old 07-29-16, 07:13 AM
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There is no reason why that will not work and it's not going to effect the flow or pressure.
I even install shutoff's for the shower/tub so the whole house does not need to be shut down to work on it.
 
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Old 07-29-16, 07:31 AM
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That's traditionally how it was done with copper and you can do it that way with PEX as well, as Joe said. The one advantage of using a manifold with separate runs to each fixture with PEX is that there are (in most cases) zero joints/connections between the manifold and the stub out for the fixture. Fewer connections mean fewer chance for leaks and lower resistance to flow. If the lines run through finished areas (like a finished basement, say) you don't need to provide access to valves that might be in the basement ceiling (except for the manifold, which is often exposed in a utility room).

There are disadvantages too...you have to have room for multiple runs of tubing. You may have longer waits for hot water. Manifolds are expensive (although less than multiple individual valves) and take up lots of room....
 
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Old 07-29-16, 07:44 AM
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The general thinking is PEX tubing is cheap, flexible, easy to work with. Fittings are the bigger expense. Also the tubing ID is a bit smaller than copper. All this lends itself to a "home run" install where each outlet gets its own dedicated line with no restrictions from valves, elbows & adapters. A manifold with a valve for each port makes sense in this type of install.

Home run layout makes less sense in a small home or a floorplan where all the plumbing lies in a straight line.
 
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Old 07-29-16, 07:44 AM
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good feedback and exactly what I was thinking....
I am in a house with PEX but no manifold so I was thinking to simply cut the lines in a few places and install valves in the 3/4 pipes that run to shower or other such areas which would otherwise require that I shut off entire water supply or install the new manifold.
I feel this is much cheaper and easier than a new manifold..... just wanted to make sure there is no impact on water flow / pressure.

Thanks!
 
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Old 07-29-16, 07:47 AM
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CT beat me...I type slow
 
 

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