Supply Line Size

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Claraarcher

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Hi Again everyone.

Few questions.

I called a pro to handle re-doing the water and waste rough in for a hall and master bath. The way the supply lines are now is that there are 1/2 inch copper cold and hot lines coming off the 3/4 copper main line that was feeding a tub. A few feet over are another cold/hot 1/2 copper lines that feed a double vanity and a toilet off the same 3/4 main lines.

The master bath is new so I was thinking that the old tub (will have a shower head and hand held sprayer) lines could be run into the new master bath and supply the toilet and single sink. The other two lines would be continued into the master and feed the shower stall (on valve with a hand sprayer so two taps I guess?)

Plumber said he would only run PEX and that 1/2 is enough so we didn't need to go back to the main lines and put in a 3/4 copper tee or 3/4 PEX connection.

Do you guys think using 1/2 PEX can adequately supply both bathrooms even if there are 2 sets of runs off the main line given PEX has less volume than copper?

Would 1/2 copper be sufficient or do I need to cut in a 3/4 copper tee and run 3/4 copper lines tapping off with 1/2 copper to each fixture?

would 1 inch PEX attached to the existing 1/2 copper tapped with 1/2 PEX to each fixture work?

Thanks!
 

Terry

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If I were doing this in copper.

water-sizing-chart-terrylove-40-60.jpg


And if using PEX

ipc_water_size_50.jpg


PEX is only good for two plumbing fixtures at the most. For one bathroom, that would be 1/2" PEX for the lav and tub, and 3/4" for the tub, lav and toilet.
If you're doing two bathrooms, then start with 3/4" for both hot and cold.
You may want to pull a permit and have an inspector look over what is being done.

uponor_manifold_pic.jpg
 

Claraarcher

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Thanks Terry!!

I pull permits on everything and it is all inspected to avoid issues down the road.

so if I got this right I have 32 fixture units and I assume the hot water heater would not be more then 4 so I am at 36 or less. Distance is less than 40 feet and pressure is controlled by a pressure valve and set at 50 so that should be good.

I have at least a 1" (copper) main line coming into the house but the chart says I need 1" distribution in the house?

I have 3/4 (copper) on the house side of the meter for distribution throughout the house. so they let 3/4 as supply into the house but want 1" distribution?

so to run PEX - that means I do have to go back to the 3/4 distribution pie and tap two sets of 3/4 PEX to feed the 1/2' PEX to each fixture and so long as I have 1 bath or shower, lavatory and toilet on one set I should be good?

if I just spend the $ and run copper same thing I need to tee of the 3/4 in 3/4 as the feed for the 1/2 at each fixture?

i put a very badly drawn PDF here. Vertical lines are 3/4 copper and horizontal are the 1/2 copper in the old bathroom that are cut and capped. I hope i can just run from there one set to each bathroom.
 

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Terry

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We work backwards on sizing.
We also have 3/4" water meters, but then run either a 1" poly line from the meter, or a 1-1/4" PEX line if we have three bathrooms.

I have seen house flippers run 1/2" and it's a big regret for the homeowners.
 

Claraarcher

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We work backwards on sizing.
We also have 3/4" water meters, but then run either a 1" poly line from the meter, or a 1-1/4" PEX line if we have three bathrooms.

I have seen house flippers run 1/2" and it's a big regret for the homeowners.
So am i borked here and need to redo 50+ year old mistake or can i just use the 1/2 stub outs per my Picasso quality drawing?
 

Claraarcher

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i grew up in a 3 story house with 3 full baths, washer, hot water tank 2 hose bibs, a slop sing and hot water heating and it was all 3/4 and 1/2 lol. now we have more efficient stuff and i need bigger pipe - lol
 

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Running separate smaller pipe to each bathroom will let the hot water arrive sooner. If you do the hot water recirculation, then that would not matter.
 

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Some of my friends from Seattle in homes that were built in 1920 with galvanized pipe say the same thing. You just get used to sharing water and remembering to not turn on faucets when others are using water. And even though their old faucets didn't have restrictors on them, water barely came out. So yes, old stuff is great. But if you ask us how we do new stuff, then you get a new stuff answer and the inspectors are happy.
Or we can give you the answer you like, kind of what the other forums are doing for ya, and you will feel confident that any answer you come up with, is good to go.
I like it when engineers say, I told my wife and she said, "Yes dear, very good dear." Hey my wife agreed with me. :)
 

Terry

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Running separate smaller pipe to each bathroom will let the hot water arrive sooner. If you do the hot water recirculation, then that would not matter.

That's a manifold system that starts off from a 1" manifold and then breaks down to 1/2" or even 3/8" for individual items.
 

Claraarcher

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Some of my friends from Seattle in homes that were built in 1920 with galvanized pipe say the same thing. You just get used to sharing water and remembering to not turn on faucets when others are using water. And even though their old faucets didn't have restrictors on them, water barely came out. So yes, old stuff is great. But if you ask us how we do new stuff, then you get a new stuff answer and the inspectors are happy.
Or we can give you the answer you like, kind of what the other forums are doing for ya, and you will feel confident that any answer you come up with, is good to go.
I like it when engineers say, I told my wife and she said, "Yes dear, very good dear." Hey my wife agreed with me. :)
Understood and i do want the correct answer i am just not sure i an following what the answer is.

I cannot redo all the pipes in the house but i do have to bring what is exposed up to code.

So i am not sure if anything i do will work for the inspector now

not one of the 3 plumbers mentioned an issue and all 3 know i expect permits and inspections so they are willing to do a job knowing it will fail?
 

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Two bathrooms
From the 3/4"
1/2" PEX to the double lav and the tub H&C
1/2" PEX to the toilet C
Half bath
1/2" PEX to lav and toilet H&C
 

Claraarcher

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Two bathrooms
From the 3/4"
1/2" PEX to the double lav and the tub H&C
1/2" PEX to the toilet C
Half bath
1/2" PEX to lav and toilet H&C
master bath has a shower stall with a shower head and hand held thingy - apologies if i did not mention that.
 

Claraarcher

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i attached a better drawing of the existing hall bath and the supply lines. The master bath on the other side is what i need to supply. The 3/4 lines are not accessible unless i tear open the ceiling below and would like to avoid if possible.

If i understand the max fixtures right 6 on 1/2 19 on 3/4 i think i cant hook up the MN lav to the hall bath 1/2 and be under 6 on that branch.

what am am not sure about is can i run 3/4 under the hall bath tub and bring it into the master? This branch would then supply via 1/2 tees the hall bath tub, MB toilet and MB shower stall. this would be the easiest solution but may not be allowed.

sorry having issues uploading the drawing. Maybe just easier to ask

1. can a 3/4 copper line supply a tub, toilet and shower stall if the total fixture on the 3/4 is under the max and the feed to each item is 1/2 copper?

2. Can i use 1"pex off the 3/4 and then 1/2 copper tees off the 1" PEX to supply each fixture?
 
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Claraarcher

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ok got a drawing that will upload.

This is what i want to achieve. Thicker line are either to be 3//4 copper or 1" PEX B.

The 1/2 copper to the double lav and toilet are not accessible so i hope to leave them and add the master Lav to that line.

The rest would be feed by the 3/4 copper or 1" PEX. I just don't know if that is ok per code or will there be issues if both tub and shower are in use at same time of if someone flushes the toilet while the shower or tub is in use.

new supply.png
 

John Gayewski

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What is the longest run of piping to the most remote fixture? That's you determine the footage. If your using the 40' column then your saying from the meter to the water heater then from there to your last fixture is your longest run of pipe and that's 40'?
 

Claraarcher

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What is the longest run of piping to the most remote fixture? That's you determine the footage. If your using the 40' column then your saying from the meter to the water heater then from there to your last fixture is your longest run of pipe and that's 40'?
well ain't i stoopid. the water meter is outside duh so probably another 35 foot to where the pipe enters the house and it is 1" main line into 3/4 PCV set at 50 PSI but can go higher as city pressure is quite high was at 70 PSI i think which is why i put the PCV on the line.

just measured from where the pipe enters the house and it should be just under 40 foot in distance, height is one story plus height to shower valve so maybe 12 foot at most.

so are we looking at 35+40+12 = 82 feet?
 

John Gayewski

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So using 84 feet of pipe and 44 psi map out your piping on paper using the plastic pipe chart. This will be the most stringent. Start at the service, and meter, then skip to most remote fixture work your way back sizing each pipe segment. Change the ones you have access to, leave the ones you don't have access to. The inspector shouldn't ask for much more than that. No one is going to answer a convoluted question about mixing all different kinds of pipe and tell you if it's going to work.

It sounds like you could bump your regulator outside anyway so even if you size it improperly here and there the bump in pressure will even out the mistakes.
 

Claraarcher

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So using 84 feet of pipe and 44 psi map out your piping on paper using the plastic pipe chart. This will be the most stringent. Start at the service, and meter, then skip to most remote fixture work your way back sizing each pipe segment. Change the ones you have access to, leave the ones you don't have access to. The inspector shouldn't ask for much more than that. No one is going to answer a convoluted question about mixing all different kinds of pipe and tell you if it's going to work.

It sounds like you could bump your regulator outside anyway so even if you size it improperly here and there the bump in pressure will even out the mistakes.
i cannot go back to the meter my only option is to do the best set up using the pipes that are there and hope the inspector will approve the plans. if they do not then no master bath. where i live plumbers now want 1500-2K per fixture to rough in so going back to the meter would mean giving up a first born child.

I am assuming using 3/4 to the new bath is the best option at this point?

edit - sorry mis-read what you said - i think we are on the same page but in the end the biggest i can go to is 3/4 anyway right?

or would there ever be a reason to go from 3/4 copper to 1 inch copper? going to 1"inch PEX would cost me about the same buying tools and fittings so lets just go copper.
 
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