[Bud9051]

Not sure where this fits best.

I was watching "the new this old house", I think that is what it is called, and they were talking about a different pvc pipe now required for gas water heaters, it is black. Apparently the standard pvc us failing in time and breaking.

What a can of worms if all sealed combustion installs (don't think they mentioned furnaces and boilers) will now need to have their exhaust pipes replaced.

Since I can't be sure I caught all that was said (CC) I'm asking if this is old news or new. Never seen black pvc in that application.

Bud

 

[Yodaman]

I saw some of that episode too, think it was referencing both furnace and HW systems (high efficiency) that use PVC for venting.

Didn't catch it all, but here is a article detailing what is happening and why.
https://www.plasticsnews.com/articl...venting-producers-seek-code-update-for-safety

It is about a year old but still informative.


I don't believe either of my local suppliers carry anything other than standard PVC for venting.


I Just did a furnace install a few weeks ago. I know if they had a new vent pipe available they wouldn't missed a chance to up-sell.

 

[Bud9051]

Thank you sir. Watched the video and Wow can't believe this is the first time I've heard of it. If I were a consumer and had the old pvc installed I'd be screaming.

How much pvc is used internally on a high efficiency appliance where that might need to be replace as well?

I'm thinking that some updates could run several hundred dollars and home owners aren't going to want to foot that bill. I'll have to check to see what Maine's consumer laws have to say.

Bud

 

[JBoot]

Using standard PVC water pipes for hot exhaust gases never did seem to make much sense to some. But if the appliance manufacturer said it was okay...
This is the 1738 system.

 

[Yodaman]

I have a install manual out my shop for Mars equipment, MFG of YORK, Comfort-Aire and a few others high Eff furnaces. Going to look at it tomorrow regarding venting requirements. Honestly, think it just says to use sch 40 PVC.

Not sure how serious or wide spread the problem really is. Or is this the plastic industry highlighting a few tragedies to build a new sales stream.


When ever I put my hand under a HE furnace vent pipe, it is barely warmer than my body temp. Much cooler than dryer vent. If I had to guess, I would say 105-110F. No where near the 150 mark, you would get 3rd degree burns in just a few seconds.

Not saying a unit couldn't malfunction and get hotter, but there are multiple safety switches to shut down a furnace running too hot.

 

[JBoot]

I think this is part of the battle between the appliance manufacturers and the companies that make PVC. The appliance manufacturer states to use PVC, and the code inspector interprets that as code compliant.

The PVC manufacturers claim their PVC was never made for flue gases. "Don't sue us for someone using something for a purpose that it was not intended."

Also, some experts point out that the corrosive flue gases/liquids dissolve the PVC cement. This new super duper 1738 compliant stuff will solve that problem!:smile:

 

[Yodaman]

Looked over the install manuals for the comfort-Aire HE furnaces that I have been installing. And as suspected, no mention of UL 1738 specification, Only SCH 40 PVC D1785, or PVC-DWV per D2665. Heck it even allows for SDR-21 and SDR-26 pipe which is a thinner wall.

The spec/requirement will likely change in the future, as all codes gravitate toward safer is better.

Going to flag this thread and request it be moved to the HVAC forum, maybe some of the pro's will chime in and shed some more light.