# Sealing vent pipe joints



## OhioBurner© (Oct 15, 2014)

So I know due to the forced draft nature of the pellet stoves that the joints need sealed with high temp silicone. If I remember correctly the manual says twist lock joints don't need to be. I have pelletvent (duravent) twist lock between my stove and my existing chimney. The joints don't seem all that air tight to me, do you folks seal those too or not? I was also unsure exactly what type of sealant. When I lined the chimney a couple years ago I used some 'Hi-Temp Silicone Sealant, black -75F to 500F'. Seemed to have the consistency of regular silicone, and I got the impression that it would be removable if needed though I never tried. This is possibly just a temporary install for this winter so I would like it to be removable. Anyhow a buddy who just did and install said he had only one joint to do and almost a full tube left over and gave it to me. However this stuff is quite different. Its 3M Fire Block Sealant FB 136. Grey and up to 1382F. He said it was more the consistency of liquid nails? I'm a bit nervous this might be hard to disassemble. Does anyone have any experience with that? Should I get something else that’s acceptable but not so permanent? I have to seal the appliance adapter to the stove and the adapter that connects the pelletvent to the 6" snout of the tee thats in the existing chimney. Thanks for any advice!


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## mixpat (Oct 15, 2014)

I use high-temp silicone tape to seal pipe sections.  No mess and easy to remove if needed.


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## Wilbur Feral (Oct 15, 2014)

Go to Lowes or a stove shop, spend about $2.49 and get a tube of high temperature silicone sealnt.  Here's a link: http://www.lowes.com/pd_305603-85334-KK0321_0__?productId=3432322.  I think the Permatex brand is RTV, which is what most call all these high temp, red silicone sealants.

However...  Put that only on joints you do not need to take apart.  New silicone will not adhere to cured silicone, so you need to remove all the old stuff if you reinstall.  Giant pain, and often not successful.

To allow for cleaning, I use the silicone on permanent joints (on the inner pipe and the outer, personally), and then for joints that must come apart I use no silicone and wrap the outer pipe with silicone tape designed for high temperatures, available from an auto parts store. You aren't supposed to NEED the silicone with Duravent or other twist lock venting, but then there's real life.  Personally, I've never had a Duravent joint that didn't leak unless sealed with sealant or tape.  Just don't try to get by with tape for everything.  Use it only where necessary for removal to clean.


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## Mt Bob (Oct 16, 2014)

ok,you did not even say what type of stove your temporary install is.Amazes me people even replyed.People getyour heads out of your asses!!


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## OhioBurner© (Oct 16, 2014)

The one in my sig bob bare, if that makes a difference on what silicone to use.

I did mention temporary but I guess that wouldn't matter - I'd need to be able to disassemble a couple of the pieces for cleaning anyhow, fwiw.


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## dlehneman (Oct 16, 2014)

I have had to seal every joint of both my Duravent twist lock installs with RTV sealant on every joint or I get minor smoke leakage on startup. It definitely makes it difficult to get apart, but I only need to remove the clean out cap on my t's and the outer caps which I don't seal. My basement install I just did I actually used both RTV and aluminum tape just to be safe. Harder to vent the basement if need be and that stove will run hard all winter. There's not even a hint of smoke now


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## OhioBurner© (Oct 16, 2014)

Wow I guess duravent isnt the quality I expected!  To facilitate easier removal for the seams that need to come apart I may try as Wilbur and mixpat mention and try to find some of this high temp tape.

One issue that I'm seeing now is how best to seal the piece that goes into the snout of the tee on my chimney. Its inside the old clay 8" thimble so kind of hard to get at. Actually, then there is the snout on the tee itself, that really isnt sealed (2-piece tee), but needs to be removable if I ever need to pull the liner out of the chimney. Well maybe I don't need to worry about that, the only reason I'd do that was if it was defective in which case I could use any means necessary to tear it apart. But I'm not sure how I would get in there to seal it well its about a full arms reach through the thimble.


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## dlehneman (Oct 16, 2014)

Here is one version of that silicone tape: http://www.amazon.com/X-Treme-Tape-..._sim_sg_6?ie=UTF8&refRID=0NR8NK4QJW12YV6MWSQX

I would've used that instead of aluminum tape, except that I had the aluminum tape laying around and no other use for it!


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## Bioburner (Oct 16, 2014)

I have used silicone self bonding tape with the best results. Aluminum tape ok but if any wrinkles it will leak. Silicone caulk only on permanent joints outside as don't look as good and  if a pinhole or two it won't matter.


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## pell it (Oct 16, 2014)

http://m.homedepot.com/p/Nashua-Tap...-Fusing-Silicone-Tape-Black-1208952/100206050


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## OhioBurner© (Oct 16, 2014)

Thanks fellas never even heard of the silicone tape before.


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## alternativeheat (Oct 17, 2014)

OhioBurner© said:


> Thanks fellas never even heard of the silicone tape before.


Ya the Duravent tends to leak. I sealed all the twist joints on assembly but then had a leak at the T which is in my fireplace. That was last spring. The leak was in the T joints themselves not the twist lock joint. Now I think I have a leak at the connector on the stove flange, not sure because at the moment it's too warm to run the stove but I saw some staining at that connection yesterday. I RTV'd that on assembly though but there is a tan tracing at the joint running along the stoves collar and I get one wiff of smoke when the convection fan kicks on at start up of the stove. I have no OAK yet ( wrong pipe came in) and the intake for the convection is right there, so this is not coincidental or just dust I have found at the flange. I think I will clean that up and tape it. It will actually be easier to tape it up than run silicone RTV around the collar I think. I don't know, I used a pretty liberal amount of RTV inside the pipe before I slid it on that collar but it appears to be leaking on start up this year . The Duravent has been a bit leak prone at any rate.

On another note we have a Smoke/Co detector maybe 15 ft from the stove, it has never gone off due to the stove. It's always going off from frying stuff in the kitchen so we know full well it works ( the tenant calls over, "is Dawn cooking again", yes Tim she is some day she will get the stove vent turned on before the alarms go off !) !!


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## TimfromMA (Oct 17, 2014)

I use Duravent with no extra sealant and have never had a problem.


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## pell it (Oct 17, 2014)

I re-named mine Duraleak!


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## OhioBurner© (Oct 17, 2014)

How about all the seems on the elbow pieces (not between the elbow and next piece but within the elbow itself)? I have two elbows, should I seal around those too while I am at it or are they usually good? On the interior it looks really good, seems almost like just 1 piece but I know its got to be seamed in there.


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## dlehneman (Oct 17, 2014)

My 45 degree elbows leaked at the joints, but I didn't have that problem with my 90 degree elbow (different install but same brand-Duraleak). You could either just seal them all to be safe, or fire it up and look carefully while it's in startup (that's when you get the most smoke and usually notice any leaks).


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## Bioburner (Oct 17, 2014)

If any doubt, seal it. Nothing like the temps at -20 and smelling smoke!


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## richkorn (Oct 17, 2014)

Hi-temp silicone (or tape) is not needed at all to seal the joints ......................... If you use ICC Excel!


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## Bioburner (Oct 17, 2014)

richkorn said:


> Hi-temp silicone (or tape) is not needed at all to seal the joints ......................... If you use ICC Excel!


I can seal most venting with one roll of tape for less than $10


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## alternativeheat (Oct 17, 2014)

richkorn said:


> Hi-temp silicone (or tape) is not needed at all to seal the joints ......................... If you use ICC Excel!


Or self sealing Selkirk. But alas, we are talking about the lower cost Duravent some of us already have installed. Sure rip it all out, spend $500 to a grand on install materials , or $10 on a roll of tape and $3 for a tube of silicone. Either is a perfect plan, just one is crazy in that its costly !


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## OhioBurner© (Oct 17, 2014)

And I thought Duravent was expensive! lol Well I’ll remember to at least look at those other brands if I do another install.


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## richkorn (Oct 17, 2014)

alternativeheat said:


> Or self sealing Seilkirk. But alas, we are talking about the lower cost Duravent some of us already have installed. Sure rip it all out spend $500 to a grand on install materials , or $10 on a roll of tape and $3 for a tube of silicone. Either is a perfect plan, just one is crazy !



This is just a heads up for people thinking of putting in a PS. If you read the threads here every day there are tons of newbies looking for advice. My advice is do it right the first time. Don't use Duravent.... There are other options without the headaches, and smoke.


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## pete7713 (Oct 17, 2014)

I used duravent pro, no tape,no leaks,no regrets


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## Mt Bob (Oct 20, 2014)

OhioBurner© said:


> The one in my sig bob bare, if that makes a difference on what silicone to use.
> 
> I did mention temporary but I guess that wouldn't matter - I'd need to be able to disassemble a couple of the pieces for cleaning anyhow, fwiw.


 Sorry.


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## Mt Bob (Oct 20, 2014)

Buy the way new duravent has silicone rubber seals like icc.


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## OhioBurner© (Oct 22, 2014)

I was wanting to get this thing running so I actually used metal tape that I had on hand. Figured I could redo easily with silicone tape if the al tape leaked. Used the high temp fire block sealant stuff on the appliance connector. No leaks I can tell so far. Only issue was I'm not able to seal a couple of the connections to the chimney liner... The ones that are inside the thimble. But can't detect any leak there so far, and the small gap between the 3" to 6" chimney adapter and the 8" thimble it passes through I was thinking about stuffing with Roxul batting to at least seal off the thimble from the house interior. I had already done that deeper in the thimble around the snout of the tee to seal the chimney off from the house when using my Shelburne there, but now I have 2 connections just before that point that I can't really get at to seal.


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## OhioBurner© (Oct 22, 2014)

Oh and I misspoke earlier, the manual doesn't say non twist lock joints have to be sealed, it says they have to be secured with 3 sheet metal screws (all joints need sealed, regardless if its twist lock) just for clarification.


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