Another Way to Seal Stove Pipe Joints???

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BurnIt13

Minister of Fire
Jun 10, 2010
623
Central MA
This topic has been covered many times but I'm having a hard time finding a definitive answer. The question comes up on using high temp silicone sealants to seal the stove pipe joints. The typical answer is....just use stove/gasket cement. Well I tried that....and failed.

But I may not have done it correctly. My stove pipe was already together and was installed without cement or sealant. I applied the furnace cement over the seams. It worked for the winter but now everything is just flaking off and falling to the floor.

So my questions are as follows:
1. Is it useless to try and apply a sealant over the seams? Or is the only way to do this successfully is to take the stove pipe apart and apply it to the female end of the pipe, then reassemble?

2. Silicone sealants over the outside. Yikes! This has been covered and the answer is maybe. Companies like Rutland, Boss, 3M, etc make siliconized sealants that remain pliable with a service temperature up to 800 degrees F. Rutland in particular makes one in black (the others are red) that is just fine up to 550F.

Now on single wall its a definite NO. But what about double wall? If my double wall was over 550F my chimney went nuclear probably would have to be replaced anyway. What do you think?

Take the stove pipe apart, fill with stove/gasket cement, then reassemble? Or go with the high temp silicone over the seams (much easier)?
 

Highbeam

Minister of Fire
Dec 28, 2006
17,230
Mt. Rainier Foothills, WA
Not sure why you think you need any sealant at all on interior stove pipe. The joints are tapered fit and no sealant is necessary. If you have a loose joint then you are doing something wrong. Some stoves require a sealant at the collar but even then, I would hesitate.

Perhaps you're pulling your hair out over nothing? I bet it looks terrible.
 

realstihl

Minister of Fire
Dec 4, 2007
525
eastern kansas
I used high temp silicone on my dsp because it was wasn't drawing properly. The fit was terrible so I took it all apart and sealed all seams. Made a big difference. I think the two 90's had something to do with the draw. This year I'm using two 45's.
 

BurnIt13

Minister of Fire
Jun 10, 2010
623
Central MA
I believe I installed the pipe correctly, it only goes together one way :) But a couple of the seams are drawing air, I used an incense stick to check. The telescoping piece was the worst.
 

realstihl

Minister of Fire
Dec 4, 2007
525
eastern kansas
I'm really considering changing out my whole setup from DSP to DVL. Supposedly it has a better fit and finish. I picky when it comes to stovepipe fit.
 

Backwoods Savage

Minister of Fire
Feb 14, 2007
27,812
Michigan
This topic has been covered many times but I'm having a hard time finding a definitive answer. The question comes up on using high temp silicone sealants to seal the stove pipe joints. The typical answer is....just use stove/gasket cement. Well I tried that....and failed.

But I may not have done it correctly. My stove pipe was already together and was installed without cement or sealant. I applied the furnace cement over the seams. It worked for the winter but now everything is just flaking off and falling to the floor.

So my questions are as follows:
1. Is it useless to try and apply a sealant over the seams? Or is the only way to do this successfully is to take the stove pipe apart and apply it to the female end of the pipe, then reassemble?

2. Silicone sealants over the outside. Yikes! This has been covered and the answer is maybe. Companies like Rutland, Boss, 3M, etc make siliconized sealants that remain pliable with a service temperature up to 800 degrees F. Rutland in particular makes one in black (the others are red) that is just fine up to 550F.

Now on single wall its a definite NO. But what about double wall? If my double wall was over 550F my chimney went nuclear probably would have to be replaced anyway. What do you think?

Take the stove pipe apart, fill with stove/gasket cement, then reassemble? Or go with the high temp silicone over the seams (much easier)?

Even though most times you can get by without sealing, I have always used furnace cement. We put the cement on the male end and then insert it. Then just use a wet cloth to wipe off any excess. Also, install 3 screws.

By putting the cement on after inserting, yes, that stuff will dry and crack and just fall right off by the end of the heating season.
 
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Danno77

Minister of Fire
Oct 27, 2008
5,008
Hamilton, IL
Just seconding the above post. Wipe it onto the crimps before assembly and wipe off excess after pressing them together. Make sure you are staggering seams, too. If you just wipe cement on after they are put together you are guaranteed two things: 1. A butt ugly install, and 2. Cracking failing seal within a season.

High temp silicone is NOT to be used for this, it isn't rated high enough to be used within, I dunno, 6 feet of the stove!
 

tcassavaugh

Minister of Fire
Jan 10, 2010
1,047
Southern Maryland
never had to use cement to join the pipe....sounds a bit odd, but i guess if you need to; you need to. a little draw at the joints probably doesn't hurt anything but then again, how much is a little. good luck. just wondering, what happens if you have to take it apart to clean it?

cass
 

Medman

Feeling the Heat
Jul 8, 2008
460
Sault Ste. Marie, Ontario
Just moving this post up - Backwoods, what does happen when the pipe is taken apart to clean?
My location (at the base of a hill, next to the water, surrounded by tall trees) is the worst possible location for draft - I have a near-constant downdraft on my chimney. The woodstove in the house has a venturi-style cap, but the boiler does not, and I get smoke leaking out of the pipe joints - especially when using the draft inducer.
I have tried various methods, but have not tried to seal joints with cement during assembly.
 

Backwoods Savage

Minister of Fire
Feb 14, 2007
27,812
Michigan
Naturally if you take the pipe apart, the seal is gone. Cement will be hard and somewhat brittle. We've never had that problem simply because we never take the pipe apart. It works great having a tee at the bottom so you can do a bottom up cleaning with no taking apart except for removing the little cap at the bottom of the tee.

You have a unique situation for drafting. We have the trees but not the water and the hills here are mostly bumps.

On the cement, it is easy to put on and easy to clean up afterwards. Simple wet cloth cleans it all up. It is funny watching but my wife usually likes to put the cement on....using her bare fingers. I usually try to get her nose to itching. ;lol
 

PapaDave

Minister of Fire
Feb 23, 2008
5,739
Northern MI - in the mitten
I use hi-temp caulk. After a year, it starts crumbling and flaking.
I've put it IN the joint and ON the joint. Does the same thing. See above.
This pipe is made to go together (slip pipe), from the same manufacturer and no matter what I do, it leaks and affects draw. It's made very well, is welded seam, and 22 gauge steel.
Evidently, it's not made well enough.
Where are you guys getting pipe that doesn't need a sealant of some sort?
 

HighHeat22

Member
Sep 29, 2011
145
southern michigan
I had to use cement on my inside joints to improve the draw. It did help alot. When I cleaned my stack I noticed more buildup was lower on the interior of the single wall pipe. From a thread on the forum I was told I had leaks on the single wall that was drawing air and causing this. When I sealed the interior single wall it did help alot.
 
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PA Fire Bug

Feeling the Heat
Jan 13, 2010
302
Blair County, PA
I used furnace cement for the first time and noticed a big difference. My pipes (single wall) had gaps where the seems where bent together. I used furnace cement where the last section of stove pipe fits into the pass through in the wall as well. I also used silicon sealant to close a pretty big gap in the clean out at the base of the chimney. In the past, I could rarely close off the air completely and still get a good burn. Now, I can shut the air down on a hot fire and have nice blue and purple flames dancing for a long time, even with less than a full load of wood. I'm looking forward to longer and hotter burns when the weather gets cold.
 

Highbeam

Minister of Fire
Dec 28, 2006
17,230
Mt. Rainier Foothills, WA
I suspect that the "need" for sealant is really just a want. It's not as though smoke is leaking out and unless you have a pretty lousy setup, the slight leaks of fresh air would go unnoticed. If you want to convert a marginal chimney into a decent chimney, adding sealant of some sort to each joint might give you that push.
 
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ScotO

Guest
Didn't somebody on here last year make a post about putting a layer or two of aluminum foil at each joint before sliding the pipes together? If I remember correctly, it made a noticeable difference.....

Sometimes it's hard to get single wall to seal good at the joints, it's just the way the pipe is crimped and the seam in the pipe. But the above mentioned method helped out a couple of people. Worth a try....
 
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rideau

Minister of Fire
Jan 12, 2012
2,168
southern ontario
I use hi-temp caulk. After a year, it starts crumbling and flaking.
I've put it IN the joint and ON the joint. Does the same thing. See above.
This pipe is made to go together (slip pipe), from the same manufacturer and no matter what I do, it leaks and affects draw. It's made very well, is welded seam, and 22 gauge steel.
Evidently, it's not made well enough.
Where are you guys getting pipe that doesn't need a sealant of some sort?
ICC double wall
 
S

ScotO

Guest
I like the single wall pipe because of the ease of disassembly when it comes time for an inspection/cleaning. I take the inside pipe out once in the middle of the heating season and give it a good cleaning. That usually happens around the end of December, when the shoulder season fires are pretty much done with and we're building good, hot, constant fires. That gives me a spotless pipe right through the winter. Not to mention the extra heat I get off of the single wall in the house. I think the biggest benefit to the double wall pipe is that it gives you closer clearances inside. I have single wall inside and Class A through the wall and up to the cap.
 
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