# pex vs copper piping sizes



## dichroic (Jul 26, 2009)

Hello, I'm having my house re-plumbed by a plumber and he is telling me that 1/2 inch PEX is ok to substitute for 1/2 inch copper pipe. Looking at the diameters of the two pipes the copper is definitely larger than the PEX. Is it ok to use the 1/2 inch PEX? My house is plumbed with 1/2 and 3/4 inch copper and he wants to replace both with 1/2 PEX and 3/4 copper. Sure doesn't sound right to me. Any help please. The 1/2 copper runs are not longer than 5-6 feet. Thanks.

donald


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## Just Bill (Dec 21, 2008)

The pipe size listed is the inside diameter, so 1/2" is 1/2" inside, matters not what the material is.


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## buddy builder (Jul 26, 2009)

pex is fine. use it. the smaller diameter inside will help you get hot water even faster to the hot side. i am a certified master plumber and can tell you for a fact that pex is the way to go. thanks, buddy builder


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## buddy builder (Jul 26, 2009)

also, just bill states the pipe is measured on the inside. not true. what you are seeing is the pex is smaller inside than copper. i sweated copper for thirty years and went to pex about 3-4 years ago and never looked back. if someone wants me to use copper and not pex i will tell them to get another plumber. it has a much higher freeze resistance than copper too. it also weighs in at about half the cost of copper. just make sure no crimp fittings are exposed to the elements because they are what can freeze as easily as copper. you are welcome world, buddy builder


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## dichroic (Jul 26, 2009)

*thanks*

Thanks for the replies. The smaller inside diameter is what I was concerned about, thinking the volume of water delivered would be less with the PEX than the copper, but guess that's not the case. Will be using the Wirsbo system. 
donald


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## RippySkippy (Feb 9, 2007)

One of the things you need to remember is that most fixtures reduce the water flow in their internal ports....so even if yo uhad 1" pipe running to each fixture, you'd only still have the reduced volume on discharge. An exception is the high volume roman faucets used for whirlpool tubs...the use nearly a fully port. Measuring the pipe is one thing...measure the internal diameter of the fittings...it's closer to 3/8". 

Another important consideration is the overall design, is it a home run design, modified with manifolds, or "typical". That will determine you flow needs and hopefully your plumber is taking that into consideration. FYI...I have have a bath group (2 vanities and shower) on the same run and the 1/2" line works well. The only problem is it's about 70 feet, so the first one to use hot in the AM has to wait a bit....but it's not too bad. When I built the house I used a home run design but each hot had the hot delay...so I moved them to one line and it's worked well.

I'm really happy with the PEX...no reason to not use it in residential construction as far as I'm concerned.


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## dichroic (Jul 26, 2009)

Thanks for the info. We are not doing a manifold system because it's a re-plumb and there just isn't enough room for all the tubing, but all the bathrooms are right next to the water heater and we are never at a loss for hot water using two showers at a time. This is turning into a really dirty job, dealing with all the sheet rock dust. But, PEX is certainly a nice product. We are using some shartbite fittings in the hard to reach places. Hope they hold up. It's hard to imagine that something so easy to use will work over time. 
donald


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