# New cold and hot feed to a new bathroom

Discussion in 'Shower & Bathtub Forum & Blog' started by Rngr275, Jul 18, 2012.

1. ### Rngr275New Member

Joined:
Mar 26, 2012
Location:
Upstate NY
I am having a new bathroom put in and I am trying to figure out the supply line lay out. The bathroom will have a shower stall, toilet and sink. Water suppy will be from the cellar to the second floor. There is only room for a couple Pex lines up the the bathroom maybe more. I was thinking about running a hot and cold pex line up then manifold/tees/??? to the fixtures. Not sure what size PEX to use 1/2 or 3/4 or if I need seperate PEX feeds from a manifold in the cellar. That would be difficult but I might be able to figure out a way. My thought was to (and I am a rookie at best) Run a 3/4 cold up to feed all 3 fixtures and run a single 1/2 hot up to feed the shower and sink (less volume to exchange to get hot water to the shower).

Also, is it better to use/build a manifold or use PEX tee's?

Thanks
McD

2. ### TerryAdministratorStaff Member

Joined:
Aug 17, 2004
Occupation:
Plumber
Location:
Bothell, Washington
Running a 3/4" cold and a 1/2" would work fine for that. You can tee off in the bathroom for the individuals.

4. ### jadnashuaRetired Defense Industry Engineer xxx

Joined:
Sep 2, 2004
Occupation:
Retired Systems engineer for defense industry.
Location:
New England
If you have a large tub, or plan for multiple shower heads, or someone may be using the sink while you're in the shower, use 3/4" for the hot as well up into the room, and consider running 3/4" to the tub/shower, then convert to 1/2" at the valve (unless you buy a 3/4" valve!). The sink could probably get away with even 3/8", but to fill a tub, more is better. Keep in mind that the internal volume of a pipe is Pi*r^2 - the squared factor means that a little difference in r means a BIG difference in cross-sectional area and the pipe's ability to flow with minimal losses and greater volume. If it were only a single shower, 1/2" pex would likely be fine. Pex is smaller ID than copper, so 3/4" pex is only nominally larger than 1/2" copper. The fewer fittings and smoother curves of pex allows it to flow with less restrictions, but that is only part of the equation.

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