Re: bathroom addition: Water supply lines
Posted by Deb on April 20, 2003 at 11:49:19:
In response to Re: bathroom addition: Water supply lines
: I live in a old 2 family home in the Boston, Mass area. I am adding a second bathroom on the second floor. I am near the main soil stack so I have had no problems with drainage and venting and now having finished that I am moving on to the supply lines. Currently the entire second floor is served by 1/2 inch lines that run from the basement. I can easily tap into these for the new bathroom but I was worried about putting too many fixtures on these 1/2 lines. My total fixture units would be jumping from 18 to 23. There is a 3/4 inch cold water branch line in the basement but the hot water heater is served by a 1/2 inch line so I wasn't sure that running new 1/2 lines from down there would be any different than tapping into what I already have access to.

: thanks for your help

Since your water lines are so grossly undersized make absolutely sure that you have installed a pressure balance or thermostatically controlled tub/shower valve. The chances of scalding is great with a regular valve.
I never put more than 5 fixture units or 2 fixtures on 1/2" line. Actually, 3/4" line is not even big enough for 23 fixture units--you should have 1" line when you get above about 17 fixture units (total fixture units depends on several factors). Remember, when you double the diameter, you 4 times the volume--3/4" pipe has over twice the volume of 1/2" pipe.
The Pipewench

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