vent pipe to chimney connection

snugone

The area where the vent pipe for my oil fired boiler connects to and goes into the chimney needs some work. I have never worked on a chimney before and I want to do it the complete and proper way. This will probably be a spring project as I expect it will require enough downtime, and for this winter I'll probably slap on a superficial coat of cement, but so that I had a few months to think over the procedure I figured I'd turn to the forums now.

The boiler was installed squeezed up against the chimney, with only enough room for two 90's to get it into what looks to be an old 8-inch opening repurposed for the 6-inch vent pipe.

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The cement is all broken and loose around where the 6-inch receiving collar was cemented into the 8-inch opening. The cement around the 8-inch section isn't too great either for that matter, as it has curled away from the cinder block.

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With the vent pipe removed, one can see beyond the short 6-inch collar into the expanse of 8-inch which continues and meets more or less with the 7-inch square clay liner.

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I only have a vague guess as to what should be done, but I was thinking that I could tear out the 6-inch collar and cement, and put in a 6-inch tube running the full length to the clay liner and then fill the void around it with something such as mineral wool. Then cement the start of the pipe back into place on the outside of the chimney. Also, I wonder if it's advisable or not to remove the 8-inch pipe or just leave that as is.

Bob Bona_4

I would be thinking about a stainless liner. The rust stain running below the thimble looks suspicious.

snugone

Bob Bona said:

I would be thinking about a stainless liner. The rust stain running below the thimble looks suspicious.

If I'm going to do it right, I certainly don't mind the added cost of stainless. Regarding the stains however, from what I understand the chimney had been left open to the sky for many years and water made its way in everywhere during that time, from closet ceilings to the basement floor, and of course that staining you see. No moisture has been evident in the years since it has been capped.

I'll likely take your suggestion and go for stainless to be safe though since there's not that much pipe involved.

snugone

Bob Bona said:

I would be thinking about a stainless liner. The rust stain running below the thimble looks suspicious.

I just realized you said liner. Yeah, for several reasons a good liner should probably be installed, but that may be too high a cost to consider at this time. Speaking of which, looking down the chimney, I get the feeling that no mortar was used between the clay liner sections and only used to adhere them to the concrete block (and they are not particularly lined up for that matter either).

ChrisJ

snugone said:

Bob Bona said:

I would be thinking about a stainless liner. The rust stain running below the thimble looks suspicious.

I just realized you said liner. Yeah, for several reasons a good liner should probably be installed, but that may be too high a cost to consider at this time. Speaking of which, looking down the chimney, I get the feeling that no mortar was used between the clay liner sections and only used to adhere them to the concrete block (and they are not particularly lined up for that matter either).

Search Amazon for 6" (or whatever size you need) stainless chimney liner kit.

I think the price and time required, assuming the proper size can fit into your clay liner is very reasonable considering what is at risk.

Bob Bona_4

If you want it right, line it. Westaflex makes a nice kit with a bottom T for a small soot drop, and a pretty slick top termination. Consult them for sizing, or if you have dimensions handy, I have the charts.