Thread: Furnace venting

Came across a high efficiency gas furnace venting through the side of a wood boxed framing that houses the metal flue for a wood burning fireplace. Sorry the picture is not that good, but I circled the pvc pipe where it exits the wood boxing. The supply air is taken from the crawlspace.
Have any of you ever seen this before?...I will be returning tomorrow to pick up the radon test and will get a better picture. I had a good one and it was deleted.

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Very unusual. Any chance you were able to get a view of the chase interior from inside the attic? I wonder if the PVC pipe has the proper clearances around the fireplace flue pipe.

sidney

when did you do the inspection ??==could not open picture

cvf

Originally Posted by Nick Ostrowski

Very unusual. Any chance you were able to get a view of the chase interior from inside the attic? I wonder if the PVC pipe has the proper clearances around the fireplace flue pipe.

Will look tomorrow as the ladder I had with me would not fit in the closet. What is the proper clearance for PVC and a metal flue pipe?

Originally Posted by CHARLIE VAN FLEET

sidney

when did you do the inspection ??==could not open picture

cvf

did the inspection yesterday (monday)

Originally Posted by sidney alstad

Will look tomorrow as the ladder I had with me would not fit in the closet. What is the proper clearance for PVC and a metal flue pipe?

Clearance will depend on the flue pipe. I believe for wood burning fireplace flues it should be at least 2" but look for a stamp or sticker on the flue pipe itself. Bob Harper may chime in and give more detailed info.

Each factory built chimney or vent will have its stated clearance to combustibles lableled on it and in the manual. Most, but not all, woodburners require 2" clearance. Most but not all gas direct vents and B-vent require 1" off the vertical run.

The mfr. will state the requirements for vertical venting of the furnace. The intake should pull directly from outdoors but probably is not required by the mfr.

When you penetrate the fireblocking, the AHJ will dictate what he wants to see there. I would expect he would want to see some sort of high temperature caulking or chinking. The pvc should be smaller than the hole to allow for thermal expansion. Also look for room where it penetrates the chase wall and how it is caulked against water. The pvc should have proper support and stability so it doesn't flop around.

If the termination meets all the requirements in the code and listed instructions then it may be acceptable.

Oh, the picture is to small, you can add a more bigger picture.