CPVC for cold only???

[DX]

Came across this accidentally. In the same bin at the local HD, same fitting with 2 different brands. One says "for cold water only". Whaaaaat? Has anyone seen this? What does it mean? Why?

 

[DX]

Ok, the plot thickens. Upon further research, I found the attached warning/note on the Charlotte website.
So this opens up more questions. Why male threads only? Seems to me the male fittings go inside of female fittings, presumably metal or CPVC, which would prevent the fitting from expanding beyond its elastic limit and prevent failure. And, more importantly, why is the NIBCO fitting NOT subject to the same limitation? Does Charlotte make inferior products? Doesn't seem likely.
The other baffling fact is that Charlotte makes that general statement for all sizes of fittings (diameters). Clearly the pressure rating of pipe and fittings go down with increasing diameter so a smaller fitting, say 1/2", should be able to take a lot more pressure than a 1" fitting.
Any engineers here with a plausible explanation?

 

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[James Henry]

Seems pretty cut and dried, since you brought it up I would be leery of using a plastic male and female adapters on a hot water pipe that expands and contracts. I never have by the way.

 

[DX]

I'm not interested in using those fittings. I'm interested in the technical reasons behind it. And I'm interested in what Nibco knows that Charlotte doesn't.

 

[James Henry]

Maybe NIBCO has been sued for leaking joints and doesn't want it to happen again. Call them up and ask them. Could be any number of reasons.

 

[DX]

One other thing. Lubrizol, the manufacturer of the FlowGuard Gold CPVC raw material, acknowledges on their website that both Charlotte and Nibco are using their raw material.

 

[Jeff H Young]

I think that all plastic fitting is for cold . but we never used an all plastic adapter inside walls hot or cold we used ones with brass thread. haven't run CPVC in a 1/4 century but we never used those cheap adapters for nothing except maybe a temporary connection don't remember why but I aint going to start, was thinking of using some CPVC the other day to save some dough on a t and p drain around 20 foot some 90s and adapter but gave up at Lowes no darn 3/4 90s in the store what a joke. just ran copper

 

[DX]

I think that all plastic fitting is for cold .

Not true. Read the manufacturers' specs. CPVC is approved for use up to 180F.

Spoke to Charlotte. The recommendation against using threaded CPVC on hot water assumes the threaded CPVC fitting is screwed to a metal fitting (brass or Cu). Because of the different expansion rates, they believe after many years of lengthwise expansion/contraction cycles it's possible for the threads to strip. They believe this applies equally to male and female threaded fittings, not clear why they only put the warning on male threads.
The warning ONLY applies with CPVC to metal joints, they say it's perfectly ok to use CPVC to CPVC threaded joints with hot water. No answer as to why this isn't clearly stated in their warning.

So now we know.

 

[Jeff H Young]

Not true. Read the manufacturers' specs. CPVC is approved for use up to 180F.

Spoke to Charlotte. The recommendation against using threaded CPVC on hot water assumes the threaded CPVC fitting is screwed to a metal fitting (brass or Cu). Because of the different expansion rates, they believe after many years of lengthwise expansion/contraction cycles it's possible for the threads to strip. They believe this applies equally to male and female threaded fittings, not clear why they only put the warning on male threads.
The warning ONLY applies with CPVC to metal joints, they say it's perfectly ok to use CPVC to CPVC threaded joints with hot water. No answer as to why this isn't clearly stated in their warning.

So now we know.

thats interesting I almost never would be screwing 2 plastics together but explains a little