CPVC near single wall vent flue

Cant find a definitive answer on this. Brand new home inspection, all the homes in the neighborhood were done the same way, so obviously passed city inspections.

Other than just being dumb, is there a code for CPVC within 6" of single wall flue? Is CPVC considered combustible?

I also thought there was a code for a minimum 12" riser height of metal water supply before transitioning to plastic? Or is that just a water heater manufacturer recommendation?

Thanks



Even though CPVC is considered a combustible material it will not burn without a significant external flame source. Once the flame source is removed CPVC will not sustain combustion. Testing indicates that water filled CPVC in diameters 3" or less will pass the 25/50 flame smoke developed requirements for non-metallic material in return air plenums.

https://www.ppfahome.org/page/CPVC

2 Likes

The Plastic Pipe and Fittings Association (PPFA) recommends, that “there should be at least 6 inches of clearance between the exhaust flue and any CPVC piping so that the CPVC tubing cannot be damaged by the build-up of excessive radiant heat from the flue.”

3 Likes

Thanks. Looking for an exact code to reference, which I’m assuming there isn’t.
Since it’s a new build, the builder won’t do anything about it unless I can reference a code.

In my report, I just mentioned it could be in danger of melting, but didn’t call it a “code defect”.

Assuming that is single wall flex vent, can’t you just reference the code that applies to the clearance from combustibles? In my area it would be IMC 503.10.5

1 Like

The Sharkbite fittings may be a disqualifier. I know the fittings advertise 200 degrees max. I know flues can go 300 to 500. I don’t know if they have a distance to flue rating, I certainly couldn’t find one. If they aren’t Sharkbite, but cheap Chinese knock-offs, I’ll bet they fail a lot sooner than 200 degrees.

I wouldn’t want the heat to soften the o-ring and cause a blowout, damper 3. Next thing you know, you’ve got a big mess and you need to rebuild it, better, stronger and faster.

3 Likes

Can you connect CPVC pipe directly to a gas water heater?.

3 Likes

Yeah, I could, wasn’t sure if it was actually considered combustible or not…
The city must not consider it to be, because several other homes around had the exact same setup

1 Like

They say they will only repair/correct items not code compliant but I seldom find this to be the case.

What does Rheem say about it?

1 Like

The water heater vent pipe appears to be a piece of flexible dryer exhaust pipe. If it is, that would be an improper installation.

1 Like

While we’re piling on, the expansion tank does not appear to have mechanical support.

2 Likes

CPVC piping, in general, can safely be used at temperatures up to 200°F in pressure applications, and up to 220°F in non-pressurized applications.
Because it is rated as combustible, any CPVC pipe must be a minimum of 6 inches away from the draft hood and flue connector at the top of a gas water heater, based on Table 503.1.

I think it’s this stuff…

https://www.ameri-vent.com/products/fc/single-wall-flexible-gas-vent-connector

2 Likes

Only after we start seeing failure will there be a Code Conference of officials convened (*where there will be much alcohol consumed and hookers hired)…after which there will be codes written and #s assigned to address issues where we can already visualize problems. (why in the crap is a professional plumber using SharkBite and or cpvc??)…I usually see and expect this crap when Uncle Charlie helps his Realtor nephew on a Flip. Not on New Construction.

  • hey’ I’ve read code books and I’m almost certain they (officials) were drinking and or otherwise distracted when composing these Codes…hic.
1 Like

I’ve read that there should be a minimum of an 18” metal supply line (copper, stainless steel flex, etc) before connection to PEX. Does the same rule apply to CPVC?

2 Likes

I have always used the 18 inch rule for all platic piping but can’t find any information on CPVC.

If this passed local code, then comment appears to have pass local guidelines for instillation, and is functioning.

Problem with the city acceptance theory is many City Inspectors are not actually certified code inspectors. My city gives an employee 6 years to acquire their certification.

Or they hire subcontractors that don’t know what they are looking at… Many small towns around here do that . . .

I agree! :+1: