Power mains question: wire gauge

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I bet people are using Pex to carry air these days. Pex is displacing
copper pipe for residential water service as well. The plumber
installing Pex for part of my circulating hot water heating system
commented that if one bids straight copper, one does not win the job.

I thought about using PEX, though wasn't sure if it could take the
pressure. A faulty regulator can easily dump 120-200lbs into the
system. At least it wouldn't shatter like PVC, though. It's an idea,
though I think I already have about half the copper I need for the
job. ..though that probably means I'm short 3/4. ;-)

My other house has PEX for its water supply. I have no idea if the
house is "normal" but I don't like the stuff. Only one of the outside
faucets has any volume and the inside faucets are all weak. It seems
there is a lot more pressure/volume lost in the distribution than
there is in either the copper systems I've had in the past or the PVC
in the new place. One big advantage of PEX for water is temperature
stability (someone flushing a john doesn't scald the person taking a
shower). Another is the manifold allows one to turn off individual
appliances. It's handy for turning off the silcocks in the Winter,
though I added ball valves to the distribution system (copper) in my
VT house to accomplish pretty much the same thing.

 

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Here is some PEX data:
<http://www.pexuniverse.com/pex-tubing-technical-specs>

At 74 F, the rating is 160 psi. The installation proof test is 1.5
times that, or 240 psi. That ought to work.

As for broken regulators, if it's a real problem, I would add a simple
overpressure relief valve to handle regulator blowout, protecting more
than just the tubing.

Depending on the result, it might be something to worry about. With
copper, not so much. PEX probably not, either, but it's failure mode
would be important. PVC, absolutely!

Sounds like the installer cheaped out and used too small a diameter of
tubing/pipe. This never happens with copper pipe. Never....

I've never seen anything less than 3/4" and 1/2" in homes. Sure, I've
seen problems with temperature regulation when they cheaped out but
never a supply problem. Even 1/2" was plenty for a hose bib or a
kitchen sink. ISTM, that PEX has a *lot* more resistance than copper.

 

[rickman]

I bet people are using Pex to carry air these days. Pex is displacing
copper pipe for residential water service as well. The plumber
installing Pex for part of my circulating hot water heating system
commented that if one bids straight copper, one does not win the job.

The Romans used lead to carry their water and as a result some developed
lead poisoning. Plastic is the new lead.

Rick

 

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The Romans used lead to carry their water and as a result some developed
lead poisoning. Plastic is the new lead.

Utter nonsense. I'd expect as much, though.

 

[Jasen Betts]

The inside of PEX is just as smooth as the inside of copper pipe, and
there are usually fewer ells needed with PEX (or copper tubing for that
matter). Something else is the matter.

looking on the internet I see lots of installations with what appears
to be very fine PEX tubing.

 

[rickman]

I've never seen anything less than 3/4" and 1/2" in homes. Sure, I've
seen problems with temperature regulation when they cheaped out but
never a supply problem. Even 1/2" was plenty for a hose bib or a
kitchen sink. ISTM, that PEX has a *lot* more resistance than copper.

Just to be sure, I pulled out an ohm meter to check it and yup, you're
right, PEX has a *lot* more resistance than copper.

Rick

 

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The inside of PEX is just as smooth as the inside of copper pipe, and
there are usually fewer ells needed with PEX (or copper tubing for that
matter). Something else is the matter.

There are NO straight runs, either. Anyway, from my experience, it
sucks for water distribution. I'm not all that happy with the PVC I
have now, either. Copper is so easy...

 

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Just to be sure, I pulled out an ohm meter to check it and yup, you're
right, PEX has a *lot* more resistance than copper.

;-)