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PVC Questions


DonTx
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On today's inspection, the subject was an older home built in 1972. My guess it originally had galvanized supply lines and at some point someone switched them out with PVC.

All the supply lines I could see were white Schedule 40 PVC and Grey (not PB) PVC. I'm assuming the grey PVC was schedule 80.

Question 1: Is it kosher to mix schedule 40 and 80 fittings and supply lines? I've always been told not to mix the two. I've never seen any standard that said you could or couldn't though.

Question 2: The only times I've ever see entire homes plumbed with PVC is on the DIY weekend cabins and mobile homes. What are the pros and cons (if any) of plumbing entire homes with PVC?

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The grey is probably sch.40 electrical PVC, which has never been approved for water supply use as far as I know. Years ago I ran my old house trailer water line (the main incoming one) with that stuff, just because it's way thicker and tougher and I didn't know any better. I've never had a problem with it, but who knows what extra chemicals I've ingested?

I don't know of any reason you can't mix the fittings, as long as the use is for the lower rated one. Someone else may know better though.

One pro of PVC is that you don't have to call a plumber to fix a leak if you have half a brain. I had a line in an unheated laundry room bust once in the old mo-bile, on a Sunday long before any build supplier here was open on Sunday. I was able to get what I needed from a local country store and fix it in an hour. Total cost was about $1.50 as I recall.

Brian G.

Cut & Glue, I Can Do

Flux & Sweat, I Don't Get [;)]

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PVC is supposed to leach chemicals into water, so it's not supposed to be approved for supply systems anymore.

If that's true, this is the first I'm hearing it and I'm in big trouble.

The way I understand it, PVC from most manufacturers is acceptable for cold water supply. To be sure, I look for the certification mark NSF-pw. CPVC is needed for hot water.

Terry, the codes state that plastic supply pipes must meet ANSI/NSF61. That's what is indicated by the certification mark.

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Originally posted by hausdok

Hi,

...but it's been that way around here for the 9-1/2 years I've been here and no plumber has ever had an issue with that call...

Mike, PVC isn't allowed for distribution piping within a home, but every code I know of allows it for supply or service piping to the home. I agree it's not common, but do you know of some local codes that prohibit it's use?

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Originally posted by Terence McCann

I, like Bill, thought it was ok for cold water.

Terry, I'd say you are both right and wrong. My understanding of the main problem with PVC is that heat (hot water) weakens it significantly. From a purely practical view there would probably be nothing wrong with using it for distribution as long as it was restricted to cold only. The trouble is that the codes (UPC, IRC, IRC) don't differentiate hot and cold when they discuss what is allowed for distribution within the building. That's probably for good reason as you could easily imagine the lines getting mixed.

I called it once in a home that had PVC stretched across the crawl from the service entry to the other side of the home. At that point it transitioned to cu or cpvc. It was only really a continuation of the cold feed and, other than being poorly suported, I couldn't see that it would cause problems. The stuff was ASTM rated, etc. I called it because it would likely crop up again as a code violation when my cleint resold. Whether he did anything about it, of course, is another matter.

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For what it is worth, I have had people not buy a house that had even patches of PVC supply liine. Don't know where I got the idea it leaches, but consider I'm in good company with Mike.

In the beginning there were several colors of pvc; orange, blue, white and ivory and even black. Grey was reserved for electrical. Then Dow came out with "big Blue" service line. Up here all the Dow lines have been replaced from main to house, as they ruptured unexpectedly.

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Originally posted by Les

For what it is worth, I have had people not buy a house that had even patches of PVC supply liine. Don't know where I got the idea it leaches, but consider I'm in good company with Mike.

In the beginning there were several colors of pvc; orange, blue, white and ivory and even black. Grey was reserved for electrical. Then Dow came out with "big Blue" service line. Up here all the Dow lines have been replaced from main to house, as they ruptured unexpectedly.

Big blue is polybutylene and is under a class action lawsuit. Also is black and is used for service entrance Branch lines which are gray. All are flexible. White PVC is is rigid. CPVC is also rigid plastic.

Polybutylene is not used any more in my area except the higher PSI rated that will not burst under high pressure surges and is only used for service entrance. CPVC, polyethelene and copper is used for branch lines.

"PVC chemical leaching"? Over 30 years ago I bought an older home which had galvanized branch lines and I had to install a 200 foot service entrance so I used white PVC because it was cheap. Got to go now I am feeling weak and confused. Can't figure why. [:-crazy]

Paul Burrell

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The vast majority of homes in my area that have been built in the past 25 years will have PVC distribution lines and some areas allow PVC supply lines. Now the vast majority of new construction in my area are being plumbed with PEX.

As for Cauldwell vs. Casey, I am afraid I would have to believe Mike Casey over Rex Cauldwell. Not to say Rex is wrong but I have seen too many inconsistencies in his books over the past few years.

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