Welcome to Plbg.com Welcome to the Popular Plumbing, Kitchen, Bath Advice Site
  We're sponsored by:
The Leading Online Plumbing Supplier Since 1995
www.PlumbingForum.com
THE Dynamic Plumbing, Kitchen and Bath, Information, Advice and Sharing Forum


Over 520,000 Posts in over 150k Threads

By far the most popular positive STRICTLY PLUMBING INFORMATION SHARING FORUM board on the Net. Ask any toilet, sink, faucet, pump, water quality and other plumbing related questions here. Plumbing professional and DIY tips, tricks, shortcuts, remodeling, plumbing advice forum and blog. Please refrain from asking business, pricing, legal or any other non strictly plumbing related questions and we also ask for only positive comments and no advertising. 

New TopicSearchLog In Newest Messages
 pex vs copper flow rate
Author: Anonymous User

I am considering replacement of my copper water supply lines (circa 1960's) with a PEX system before I close in my basement ceilings. My question has to do with flow rate and volume of pex vs copper. I note that the ID of the 3/4" copper fittings for connecting pex is not much greater than the ID of 1/2" copper tubing and significantly less than 3/4" copper. I am not a hydraulic engineer, but wouldn't this restrict the maximum flow rate and capacity of my water supply?

Reply To This Message

 Re: pex vs copper flow rate
Author: Dunbar (KY)

Sure would.

You need to upsize the piping to match the id of copper to be code acceptable for your plumbing system.

Reply To This Message

 Re: pex vs copper flow rate
Author: Scott D. Plumber (VA)

If your plumbing fixtures are the good old high flow type typical of the '60s, you will notice the flow differance!

Like Dunbar said, you will need to upsize your piping for PEX to avoid flow issues.

Also, limit your joints with the PEX. That is one of it's advantages. You can get it installed with very few joints, eliminating many leak opportunities and keeping your flow to a maximum.

You should have joints at the tees and at the wall penatrations, but other than that try to make your runs in one piece.

Also use good components that secure your stub outs and keep them straight. one of the things that gives PEX a bad name is shoddy instaltion that does not make the piping secure and attractive where visible. (It should not flop all around like a garden hose!)

Reply To This Message

 Re: pex vs copper flow rate
Author: hj (AZ)

Yes, except at low flow rates.

Reply To This Message

 Re: pex vs copper flow rate
Author: Uni R

The fittings are restrictive but not as much as you might be thinking. You have to remember that a 3/4" ID pipe with fittings that are only 1/4" ID will have significantly more flow than a straight 1/4" ID pipe. The fittings do restrict the flow but only while the water is having to go through the fitting. The key with PEX is to minimize the fittings. To properly calculate the flow restrictions you have to measure the flow restrictions per foot of the pipe by its length and add the flow restrictions for each fitting. Different layouts will give different results so it is tough to compare PEX to Cu that way.

Reply To This Message


Note: Inappropriate messages or blatant advertising will be deleted. We cannot be held responsible for bad or inadequate advice.

Warning: Plbg.com has no control over external content that may be linked to from messages posted here. Please follow external links with caution.

Plbg.com is strictly for the exchange of plumbing related advice and NOT to ask about pricing/costs, nor where to find a product (try Google), nor how to operate or promote a business, nor for ethics (law) and the like questions.

Plbg.com is also not a place to ask radiant heating (try Heatinghelp.com), electrical or even general construction type questions. We are exclusively for plumbing questions.

Click here to view our old forum messages



to: Contact Us
to: Plumbing Manufacturers Address Directory
to: Plumbing Links Site
to: How to show an image
to: theplumber.com
to: Plbg Statistics
to: our FAQ's
to: Advisor List
to: Common Plumbing Terms
We're sponsored by:
The Leading Online Plumbing Supplier Since 1995
  We're sponsored by:
The Leading Online Plumbing Supplier Since 1995

Copyright© 2014 Plbg.com. All Rights Reserved.