hello again speedball,

so I've decided to tackle my pex plumbing project myself and not shell out $700 to the "I know a guy" guy. From what I've read so far, sizing pex is the same as copper, but I value your input greatly.

I am running supplies for an attic half bath. The total run for hot/cold is about 45 feet (with bends calculated in).
my question is: I know I should run 3/4" for the cold supply, then tee (3/4 X 5/8 X 1/2) at the toilet and reduce down to 1/2" for the lav (which is about 8 feet downstream). Would I be OK running 1/2' the entire length from basement for the hot (which will originate about 2 feet downstream from H2O heater), or just run 3/4" and reduce to 1/2" prior to the lav?

I am hoping any pressure drop will not be significant enough to notice, also only running 1/2" for the hot will save some cash.

your thoughts would be greatly appreciated,

louie

Hi Guy,
"my question is: I know I should run 3/4" for the cold supply, then tee (3/4 X 5/8 X 1/2) at the toilet and reduce down to 1/2" for the lav (which is about 8 feet downstream). Would I be ok running 1/2' the entire length from basement for the hot (which will originate about 2 feet downstream from H2O heater), or just run 3/4" and reduce to 1/2" prior to the lav? "

Let me quote code to you. All mains to be 3/4" with no more then 3 fixtures taken off a 1/2" branch. Your hot line will be just fine if you come off a 3/4" main. Never heard of a 3/4 X 5/8 X 1/2" tee in plumbing. Because we figure the ID of a pipe because of the volume it will carry like 1/2" a AC man will figure the same pipe at 5/8" OD for its radiation factor. Regards, Tom

"Never heard of a 3/4 X 5/8 X 1/2" tee in plumbing"

sorry tom, was getting ahead of myself. I believe I'm thinking of a 3/4 X 1/2 X1/2 , then one of the 1/2s will be reduced to 5/8 for toilet, the other will continue to lav. That should make more sense.

also, both supplies will be coming off 3/4 mains. Looks like I'll save a few bucks on the hot supply.

as always, thanks a million :D

louie

"Never heard of a 3/4 X 5/8 X 1/2" tee in plumbing"

sorry tom, was getting ahead of myself. I believe I'm thinking of a 3/4 X 1/2 X1/2 , then one of the 1/2s will be reduced to 5/8 for toilet, the other will continue to lav. that should make more sense.

also, both supplies will be coming off of 3/4 mains. looks like i'll save a few bucks on the hot supply.

as always, thanks a million :D

louie

Hey Louie,
"then one of the 1/2s will be reduced to 5/8 for toilet,"
I find two things wrong with this statement.
1) 5/8ths isn't a reduction from 1/2.
2) You'll supply the cold water to both lav and toilet off a 3/4"main using a 3/4 X1/2 X 1/2" tee. You seem to want to complicate things by changing the size of the branches. Am I missing something here? Regards, Tom

"Am I missing something here?"

Not at all, I was. In my minds eye I was seeing the attachment of a compression stop valve to the stub out as a "conversion/reduction". Which it is not. I was not differentiating between rough in and finish plumbing. Reading back I can see where things went awry. This seems like an issue of misunderstanding and miscommunication on my part. Sorry for the confusion, and thanks for your patience with a novice. :o

Hry Louie, No problem.
I don want to bust yochops but a angle stop, (compression stop valve) is a 1/2 X 1/4" compression stop made by Brasscraft. Cheers, tom