# metal chimney pipe question



## uarelovedbygod (Nov 1, 2003)

I am installing a Hotblast wood furnace in my garage, and running the chimney pipe out the side wall. I have about 7 feet of pipe running parallel to the ceiling--keeping it the required 18" from the ceiling and slowly sloping upward. I am using the chimney pipe our local hardware store sells--the kind with the seam you have to slip together, not the pipe with the riveted seam. I don't particularly care for this type of pipe, but it is all that is available here. I am installing the pipes with the seams upward to prevent creosote dripping out on the floor. My concern is that the ends of the pipe don't go together tightly. Because of this type of slip together seam, there is as much as 1/8-1/4" gap where the pipes come together. I think this may allow smoke to escape from the pipes into the room. It would not be alot of smoke, but I would prefer no leakage at all. Is there a product on the market I can use to seal these pipe joints together to prevent smoke escaping at the joints? I have a roll of the aluminum tape used on HVAC systems, but I don't know if it could withstand the high temperatures of a chimney.

Thanks!


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## Guest (Nov 28, 2008)

I think you can use high-temperature silicone sealant for that.

If I'm wrong, someone will come along shortly and correct me.


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## Beeman (Dec 29, 2002)

I've had pipe with gaps like that, no sealer required as the smoke will go right past in the draft. Be sure to put the small end down or towards the stove.


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## Cabin Fever (May 10, 2002)

As Beeman said, the "male" end of the pipe toward the stove. The gaps may leak a bit right at start up, but not once the fire is up and running and the draft is strong. Do not attempt to seal the seams because with your set-up, it sounds like you'll have to be taking the pipe apart every time it needs cleaning.


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## wvstuck (Sep 19, 2008)

I actually used a high temperature black cement for putting stove pipe together, got it at my local hardware store with the pipe and screws to keep it all together. Just a little bit will do before putting the joints together. Once it is together, let it sit for an hour or so, then slowly run the stove up to about 500 degrees to finish the cure. No smoke!


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## Ross (May 9, 2002)

The high heat silicone won't handle the heat............ I think the best you can buy is rated at 650 deg F and any wood burner can top that easily. Remarkablely if yoiu have enough run on the single wall pipe you can drop the temp to dangerous levels so the chimney won't work, especially if there are gaps in the joints. Simple test if you have the tools and numbers to ensure you have the base chimney temp to keep things working but you may not. Never mind the gaps will let creostoe escape if it starts too melt which is a fire hazard.
Try rolling the pipe into a better shape of round and using screws to snug up gaps. The metal tape does work if its ULC rated for the task but it's not normally available in big box stores or hardware stores...........(here at least) haven't seen it used on wood burners really moreso on oil fired furnaces, which run under 600 degrees F or theyd better be under that!!!


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## uarelovedbygod (Nov 1, 2003)

If I find a source of the appropriate metal tape, what temperature will it be rated for? Is it specifically marketed for wood stove chimney pipe?

Thanks!


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## Ross (May 9, 2002)

The reason wood burners use black painted pipe instead of galvanised is the zinc inj the galv detatches from the steel around 700f. Wood stoves can get those pipes glowing red so it'd be tough to say where the temp rise stops!! I know Intertape makes metal tape that will stay stuck at 700f but in the event of a chimney fire the flue temp will rise above that allowing leakage. Try rolling the pipe to get it round, or maybe you need a crimping tool to fit it tighter. Three screws per joint is a minimum you can use more if it seals the gap.


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## unioncreek (Jun 18, 2002)

YOu can get a black paste sealant/adhesive that they use to put stove gaskets in with. I've used it to seal chimney's with if they leak.

Bobg


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## Ozarka (Apr 15, 2007)

There are too many things that can go wrong with a setup as you describe. Look at Lehman's non electric catalog, do google searches for stove pipe suppliers. The manufactures of all that hardware make adapters to go from standard stove pipe to any of the insulated pipes. from what you describe you are not installing the pipe correctly. I recommend assembling the pipe on the floor and using a cordless drill with the clutch set very light (say, on 1 or 2) and using # 8 or 10 x 1/2" TEK self drilling screws , 3 per joint, to safely secure it all together. Stovepipe is required to be slipped completely snug inside the next piece. A visit to a sheetmetal shop will allow you to rent a pair of crimping pliers to make odd lengths fit together correctly. There have been too many fires with pipe that was almost installed correctly, a 1/4 inch gap is asking for trouble. One spark is all it takes and even smoke inhalation can kill you. I have had enough close calls over the past 30 years to know that tight is the only way to fit stovepipe. That much horizontal pipe will require a ball of burning newspaper to get the draft going when building a new fire in a cold stove. Bottom line to your question, there ain't no magic mending tape, only correct fittings for the application and one of those correct fittings will cost you pennies compared to a house fire...:flame:


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## mdharris68 (Sep 28, 2006)

I agree with tight joints. Take your long individual runs and lay them on the floor against the wall and use a piece of 2 by material and a mallet and beat them together. Screw 3 times at each joint and rehang.


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