# Pex sizing



## MSSI (Mar 25, 2006)

Although not up to speed on fluid dynamics.....Am i correct in deducing that running 3/4 pex is the same as 1/2 copper??/ I was looking at the fittings and it looks like the 1/2 fitting has an ID of about 3/8 and the 3/4 has about 1/2 in. So in essence the flow is restricted at the fittings. I dont have the best water pressure on this project and dont want to make it worse....Also do city water meters have any type of flow/pressue control or adjustment ??........Thanks


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## reveivl (May 29, 2005)

I'm no fluids engineer either, but the restriction won't change the pressure, just the volume. Rich.


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## MSSI (Mar 25, 2006)

yes pressure is pressure..but wouldt I get twice as much volume at 100psi than at 50 psi ??


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## King of Crown (Oct 12, 2005)

I'm about a 46d.


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## Bill (Mar 30, 2006)

Well to tell you the truth most homes probably have 9 fixture units which could be served well with pex without noticing any pressure differential as opposed to copper or cpvc. Sometimes I will run 3/4" to up through the floor and use a 3/4 x 1/2 90 to come out of the wall with. The only time you will notice a difference is if you go with more than 200 foot of hot and cold (400 foot total) In most average homes as I said pex is fine. If you think you will have a problem with adaquit pressure there is a flow rate chart that I have to use in commercial plumbing (And in some residential) Tell me, how many fixtures will you be serving and what are they? These are anything that will use water. If I know this, I could calculate the size of the water main needed. As for the second part no, the city doe's not controll water pressure at the meter nor is there any way to adjust it unless you install a pressure regulator in line. But then again you do not need more than 35 to 50 lbs of pressure to run a house.


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## MSSI (Mar 25, 2006)

3 tubs- 1 shower stall- kitchen sink- cloths washer-wash tub- dishwasher front and back spicket..on a tankless..Thank you


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