# Low Water Volume



## markalexan (Jun 20, 2015)

We have a new home with a domestic well.  The cut pressure is 45psi and the cutoff pressure is about 63psi.  The lines from the maniblock are 3/8" pex and the main line to the maniblock is 3/4". 

Our problem is that there is low water volume to all faucets and fixtures.  My outside hose bibs do not have sufficient flow to even operate a sprinkler.  From what I have read the pressure is correct.  I measured the static pressure at one of the hose bibs and it was about 58.  Is the 3/8" pex too small to provide sufficient flow?


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## bud16415 (Jun 20, 2015)

I did my whole house with ¾ pex to the manifolds and ½ as homerun lines everyplace. I am on city water now but had wells for years at other homes. My pressure and flow loss on these ½ is almost nothing amazing flow and pressure compared to the iron pipes I removed. 

I think your problem is the 3/8 pex or the length of runs. More likely the 3/8. 

Welcome to the forum.


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## markalexan (Jun 20, 2015)

Thanks.  I believe that is the issue also.  Now getting the contractor to correct the situation will be the challenge.


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## bud16415 (Jun 20, 2015)

It would be easy enough to prove out and show him. Chances are the outside lines just run across the basement. Run a 1/2 pex for one of them and see if you get a better result. Your manifold most likely is for 3/8 but you could do a tee off the ¾ feed. 

PEX is super easy to work with if you have a couple tools. The problem is in a finished home is threading all the tubing in the walls and ceiling. That&#8217;s where the builder is going to push back, but if you had a side by side example for him to look at he&#8217;s not going to be able to say to much. 

Picking the right size tube is tricky. The urge is to go big and have all the flow possible but then you have a lot more water to run thru on the hot&#8217;s to get the cold out. Outside water cold only there is no reason to scrimp on tubing size. For me 3/8 is fine going to an ice maker or a toilet anything flow rate isn&#8217;t important. Maybe you can work with him rerunning the important stuff by putting in a ½ inch manifold and keeping the 3/8 also for some of the runs.


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## beachguy005 (Jun 20, 2015)

You should make sure that your valves on the maniblock are opened all the way.


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## joecaption (Jun 20, 2015)

No way is 3/8 home runs going to be enough, and any real plumber would have known that.
It has 1/2 the CFM of a 1/2" line, and 1/4 or a 3/4" line.


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## frodo (Jun 20, 2015)

not knowing your location,  i can not tell you what code you are under.

this chart is the MINIMUM pipe size for fixtures. for the Unified plumbing Code  [UPC]





my recommendation,  talk to the builder, 1 time, advise him that by code the water piping is not up to code.
if he blows you off. its lawyer time.
send him a registerd letter, giving him 10 days to correct the problem
if at the end of ten days,  get a lawyer, show the lawyer the code
he will handle it from there.  also...if you really want to stick him good,  contact other home owners, tell them to join a class action.


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## beachguy005 (Jun 21, 2015)

Sizing for pex is based on the fixtures it's attached to.  Here's an installation manual which gives you some info.
Note page 99.  I have home runs of 1/2" and wish I had 3/8" to the sinks because of wasted water to get to hot.

http://plasticpipe.org/pdf/pex_designguide_residential_water_supply.pdf


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## frodo (Jun 21, 2015)

you still have to use the code book fixture units to size the pipe size,  

just because pex,  says you can run 3/8'' 40' does not mean  you can run 3/8'' to all the fixtures

the water piping STILL has to be sized according to FU

the UPC  CLEARLY states that ALL piping SHALL be minimum 1/2id

that right there,,throws a red flag on 3/8'' [actually 1/4''id]

the way i read the code..3/8'' is not allowed at all:2cents:


BUT,  I am not a "PEX" plumber,  I install exclusively copper piping

i run 3/4 copper to 2 fixtures,  a 1/2'' tee is only used for air chambers

on my truck...and I have NEVER had a complaint about no volume

I have clients that tell me,  "when i turn on the shower,I want it to knock me down"

never has anyone told me I want the water to dribble out, like a 70 year old man taking a leak:rofl:


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## beachguy005 (Jun 21, 2015)

That's in reference to copper tubing.  PEX is a different animal with different ratings.


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## frodo (Jun 21, 2015)

a fixture unit chart is used for all piping not just copper
The chart I posted, is used for ALL piping APPROVED  IAMPO,  which includes PEX
read 604.1   a chapter your own pex book references in the UPC.


what you seem to be not understanding,  is that yes,  the PEX book says you can 3/8'' tubing 40' to a fixture

BUT, the code,  says the minimum ID of pipe  allowed by code is 1/2'' ID.

to be run as a branch.

so in essence, the UPC is saying that 3/8" pipe for branch's is not allowed


here is 604.11  this says  that chart IS to be used on pex


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## markalexan (Jun 21, 2015)

Thanks for your input.  Here in Pennsylvania the International Building Code and associated International Plumbing Code (IPC) are the requirements.  are the requirements of the IPC different  than those of the UPC?


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## frodo (Jun 21, 2015)

yes they are, the ipc is a lot more relaxed in their codes.  a quick search of ipc code i found this

http://screencast.com/t/idVETG8a

as you can see, 3/8'' is allowed to a lav, and toilet, the other fixtures
kitchen sink, tub, hose bibs, etc  call for 1/2'' or larger

I sent a pm...to david,,our local ipc guru.  he will be along shortly and give his opinion,  i deal with upc,  and do not like the lacks ipc code.

from what i saw, the same thing is being done, 3/8 is legal for one fixture so they are running everthing 3/8

if you look a a 3/8'' pex pipe the id is actually 1/4''

i can pee more water than that


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## Chris (Jun 27, 2015)

Before you go ripping out your piping. Does your well have a wye-strainer or filter on it? Mine does and every month or two I need to clean the sediment out of the wye-strainer because I lose most of my volume. I gone from showering with the sprinklers on to getting no water from a faucet with the hose on. Take it out and hose it off and I am good to go again.


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