1/2 Line From Water Main to Manifold

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sjm78560

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Hey All,

I'm replacing my old galvanized pipes pex and have questions on diameter size water line to 2 small manifolds. My house is small and my water main is only about 30 ft from my water heater. I am placing two 4 port manifolds about 10 feet away from the water heater that will run 7 foot lines to their destinations. The manifolds are going to be located in my unfinished laundry room located right under my bathroom which is very close to my kitchen sink. These are the only places I'll be supplying water accept for my outside hose that pops out the back of my laundry room.

I was planning on running 1/2 inch pex straight from the water main and throughout the house. The 2 manifolds though have 3/4 inch main connections, so I was thinking of adding a reducer fitting that would take the 1/2 to 3/4 right before the manifolds and attached with a short piece of 3/4 pex. Would this work? Or is a better option to run 3/4 from the main to the water heater, and then 3/4 to the manifolds?

The manifolds I'll be using are below. One will be closed on one end and one will continue on to the outside hose. We kinda have bad hose pressure, Would it increase if using 3/4 instead of 1/2? Really appreciate the help!
1599800538590.png
 
For the minor difference in cost, go with the 3/4-inch. Quick rule of thumb: The main PEX trunk should be at least the size of the service line from the main. Most houses have a 3/4 or 5/8-inch feed from the water main.

And if you run 3/8-inch PEX from the manifold to the hot side of fixtures, you waste less water getting the hot water to the fixture, and don’t have to wait as long. 3/8-inch PEX has plenty of flow capacity for a 2-gpm fixture.
 
Pressure is static but flow will be much better with 3/4".
Absolutely use 3/4" for the major feed to the manifolds.
I (any plumber would) agree with FS that 3/8" are the best choice for hot water manifolds.
 

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