Question about PVC venting from a condensing boiler

gggnbc

Can PVC intake and exhaust be routed to the outside concentric vent through a joist cavity which will be enclosed by drywall?

Mad Dog_2

In NY, it isn't allowed anymore. CPVC or polypropylene or SS. Check with the manufacturers requirements. Mad Dog

lchmb

In NH you cannot use pvc on boilers.

Steamhead

PVC is not UL approved for venting combustion products, and Code authorities are finally taking notice of this. CPVC is not UL approved for this purpose either. Even if PVC or CPVC is still permitted in your area, I wouldn't use it. Use stainless steel, or something like what Centrotherm sells:

http://www.centrotherm.us.com/

You should be able to find required clearances in the various manufacturers' instructions.

adambnyc

Interesting. I vented my tankless hot water heater with PVC as per the manual instructions. In fact the Heater has intake/exhaust are PVC hubs direct from the factory. Different rules for hot water heaters? My town inspector passed me without issue.

Solid_Fuel_Man

Some (maybe most) manufacturers will list pvc, cpvc, polypropylene, and stainless as accepted venting materials in their literature. The pipe manufacturers do not approve their pipe for combustion venting, just dwv of sewer. It's been a grey area for quite awhile.

That said there are thousands, maybe hundreds of thousands of installs with pvc venting...
PVC and CPVC have the (in my opinion) advantage of being solvent welded and essentially made into a continuous piece. Polypropylene, while better material has the (in my opinion) drawback of relying on gaskets for joining. Same with stainless. If those two materials could be made continuous there would be a bullet-proof systems.

EBEBRATT-Ed

@Solid_Fuel_Man ,@Steamhead.

I am not advocating PVC use but my understanding is that there is only one manufacturer that has PVC that is listed for combustion venting.

Ipex #636 is available in PVC & CPVC and is approved for venting.

There are issues with pvc so I think it will slowly go away as a vent material

Paul S_3

I once seen a partially melted pvc exhaust on a rheem tankless water heater....I found out a scaled/dirty heat exchanger can cause this....less heat transfer to the water created really high flue temps....ive used cpvc....but now only polypropelyne products made from centrotherm.... and in nyc they will fail you immediately if you use pvc

adambnyc

@Paul S that's exactly what I have. I just check the book, schedule 40 PVC listed pg 34, top right

http://cdn.globalimageserver.com/fetchdocument-rh.aspx?name=prestige-condensing-tankless-direct-vent-indoor-condensing-tankless-use-and-care-manual

Steveheat

Peerless allows the use of Scd.40 PVC. On their Pure fire condensing boilers.

Jason_13

IPEX 636 I believe is only certified in Canada

Steamhead

adambnyc said:

@Paul S that's exactly what I have. I just check the book, schedule 40 PVC listed pg 34, top right

http://cdn.globalimageserver.com/fetchdocument-rh.aspx?name=prestige-condensing-tankless-direct-vent-indoor-condensing-tankless-use-and-care-manual

Steveheat said:

Peerless allows the use of Scd.40 PVC. On their Pure fire condensing boilers.

adambnyc said:

Interesting. I vented my tankless hot water heater with PVC as per the manual instructions. In fact the Heater has intake/exhaust are PVC hubs direct from the factory. Different rules for hot water heaters? My town inspector passed me without issue.

Doesn't matter if the boiler manual allows it- if it's against Code in your area, you can't use it. Some inspectors will pass it now, but that will change as Codes get updated.

hot_rod

Steamhead said:

adambnyc said:

@Paul S that's exactly what I have. I just check the book, schedule 40 PVC listed pg 34, top right

http://cdn.globalimageserver.com/fetchdocument-rh.aspx?name=prestige-condensing-tankless-direct-vent-indoor-condensing-tankless-use-and-care-manual

Steveheat said:

Peerless allows the use of Scd.40 PVC. On their Pure fire condensing boilers.

adambnyc said:

Interesting. I vented my tankless hot water heater with PVC as per the manual instructions. In fact the Heater has intake/exhaust are PVC hubs direct from the factory. Different rules for hot water heaters? My town inspector passed me without issue.

Doesn't matter if the boiler manual allows it- if it's against Code in your area, you can't use it. Some inspectors will pass it now, but that will change as Codes get updated.

Good point, getting the approved products in the codebooks is the first start.

Unfortunately not all jurisdictions adopt or use the most current codebooks. In my area we still use 2012 version! until the board votes to accept a newer version.

It would be nice to see the final chapter to this PVC venting issue.

Henry

S636 PVC is the same pipe as sch 40 PVC. The colour is different and the labelling is different. There are standards to manufacture PVC SCH 40 pipe and S636. The physical components to make the pipe is essantially the same. In 2007 when I was in Europe and missed our annual code meeting, Ontario passed a motion to have the venting material aprooved as S636. They claimed that IPEX made the pipe. This was not true. It took over a year to get the new labelling and colour aprooved. We, as mechanical contractors vent with S636 up to and including 6 inch if it is written in the I & O manual. The Raypack condensing boilers are very specific for the number of elbows and material as well as vent lenght. HTP & Lochinvar are the easiest to vent. On the largert condensing boilers we go with AL24C.

j a_2

I have seen yellowing of some pvc vented boilers and furnaces...Not a pvc guru, but maybe someone will chime in on it...Who knows better.