# Sealing Stove Pipe?



## boatboy63 (Jan 21, 2011)

Just wondering how many of you use a sealer on you stove pipe inside house. I have the black standard stove pipe running to a triple wall "thru the ceiling" When we first put it together the other day, it appeared to have gaps where they joined together. I did put 3 screws in the connections, 120* apart. Ended up using a stove cement on the joints, but it is too hard and seems you can hear it pop when it heats/cools. I would like to find something that can handle the heat and still flex. I know I have a very small leak at the junction between the pipe and the adapter that pushes into the box in the ceiling. Some of the cement that was put on the joints the other day, seem to have minor cracks in it.


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## webby3650 (Jan 21, 2011)

There is really no need to seal the joints, if they leak smoke you have a draft problem. A properly drafting flue pulls air in and will not smoke out.


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## cmonSTART (Jan 21, 2011)

If you want to seal, stove cement is really your best option.  High temp silicone will break down and evaporate at typical stove pipe temperatures.  I've found that stove and gasket cement holds up pretty well, even with the pipe expansion.  

But like webby said, air shouldn't leak out of your pipe unless you have a draft problem.


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## boatboy63 (Jan 21, 2011)

I understand what you guys are saying, but I am looking at it differently. There is no smoke coming back into the room...only lost room air going up thru the pipe. Since I did buy an EPA stove (Magnolia), I am just wanting to make sure I am "feeding" it properly. I was thinking of it like this, the more draft available, the better the performance on the stove. As the draft would actually be a vacuum, any sort of leak would feed the room air instead of pulling air thru the stove. Since an EPA stove requires a strong draft to work properly, any leak of it's vacuum would cause less performance.


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## cmonSTART (Jan 21, 2011)

I like the way you think.  Cram those gaps full of stove cement and you'll be OK.  If someone knows of something better, please let us know.


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## firefighterjake (Jan 21, 2011)

Thought about sealing up the stove pipe with stove cement . . . didn't get around to it in the first year . . . stove worked well so I never did get around to sealing up the pipe.


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## Jonsered (Jan 21, 2011)

boatboy63 said:
			
		

> I understand what you guys are saying, but I am looking at it differently. There is no smoke coming back into the room...only lost room air going up thru the pipe. Since I did buy an EPA stove (Magnolia), I am just wanting to make sure I am "feeding" it properly. I was thinking of it like this, the more draft available, the better the performance on the stove. As the draft would actually be a vacuum, any sort of leak would feed the room air instead of pulling air thru the stove. Since an EPA stove requires a strong draft to work properly, any leak of it's vacuum would cause less performance.



Exactly the reason I am looking to seal my stope pipe too.


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## Wood Heat Stoves (Jan 21, 2011)

millpac wont crack-up like furnace cement

http://www.shopping.com/Copperfield...ck-High-Temperature-Sealant-10-3-oz-Tube/info


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## Todd (Jan 21, 2011)

Another good thing about sealing up the stove pipe is those little seams suck in relatively cooler air which creates creosote. Before I cemented my pipes together you could see the streaks of black where ever there was a gap when I took them apart for cleaning.


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## boatboy63 (Jan 22, 2011)

Lowes sells some caulking in their paint department that is fire rated. It runs around $15 a tube. I am going to look closer at it next time I am in the store. Also, used the infrared thermometer and checked pipe temps. My black pipe is about 5' from top of stove to ceiling. I saw about a 100* drop in temps from within 6" of stove to ceiling. Is this normal or am I getting leakage from pipe where seam runs up and down?


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## webby3650 (Jan 22, 2011)

Sealing the pipe joints isn't going to hurt anything, we only use Elmers and I see no room for cement in the joints. Woodstoves put out tons of heat, try not to think it to death. ;-)


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## balsabones (Jan 31, 2011)

cmonSTART said:
			
		

> I like the way you think.  Cram those gaps full of stove cement and you'll be OK.  If someone knows of something better, please let us know.




I bought some extra fiberglass rope that is used to seal the glass, unraveled it into 1/16 strands and spot stuck it to my male end of black stove pipe. I let the silicone dry and then slid it all together. The small pieces of rope sealed the pipe. I did, "bunch" an little up at the place where you assemble the pipe, the vertical joint, so it would fill the gap. The further the pipe slid into each other, the tighter it got. No problems now.


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## woodsmaster (Jan 31, 2011)

I recently installed a gassifacation boiler and didn't seal the pipe. big mistake on a induced draft appliance, I had smoke coming from every joint. Had to take apart and seal. Used some stuff for stoves that came in a caulk tube from rutland I think.
Have a old natural draft stove in the house with no sealent and have never had a problem.


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## Trktrd (Jan 31, 2011)

I also use stove cement on the inside pipe joints, mainly because I only have a 12' chimney and need all the draft I can get. Don't need leaky joints robbing my stove draft. Kind of a pain when pulling the pipe to clean, but it's a small sacrifice for a better burn.


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## Dave_1 (Jan 31, 2011)

boatboy63 said:
			
		

> Just wondering how many of you use a sealer on you stove pipe inside house. I have the black standard stove pipe running to a triple wall "thru the ceiling" When we first put it together the other day, it appeared to have gaps where they joined together. I did put 3 screws in the connections, 120* apart. Ended up using a stove cement on the joints, but it is too hard and seems you can hear it pop when it heats/cools. I would like to find something that can handle the heat and still flex. I know I have a very small leak at the junction between the pipe and the adapter that pushes into the box in the ceiling. Some of the cement that was put on the joints the other day, seem to have minor cracks in it.



http://www.marinepartssource.com/newdetails.asp?pnumber=BA70STBC650&mfg=BUCK ALGONQUIN&mfgno=70STBC650&desc=6 9/32  to 6 19/32 in. T-Bolt Band Clamp

But it *is* like Webby stated: 

"_There is really *no *need to seal the joints, if they leak smoke you have a draft problem. A properly drafting flue pulls air in and will not smoke out. _"


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## rustynut (Jan 31, 2011)

bb63,
  Seems that you are quite worried about a very minor loss of room air............
Have you thought about an outside air kit ?
Seems to me that burning room air for the stoves combustion would be a much more substantial loss of room air ?
I have found this to give me a much more balanced system as well as eliminating the room air burning that
is concerning you.
Something to think about..........
rn


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## VCBurner (Jan 31, 2011)

If you use stove cemment you'll need to allow for proper curing.  The stuff I use is supposed to sit for at least 2 hours I think before you attempt to do some break in fires.  If you're sealing some bigger gaps like more than 1/8 " gap you'll need to allow longer curing time before breaking in the seals.  Wipe the pipe with a damp rag before applying the cemment and allow it to dry.

I have done it before and want to do it again when I finally get a liner for my chymney.


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## woodsmaster (Jan 31, 2011)

Dave_1 said:
			
		

> boatboy63 said:
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Thats true for a natural draft appliance but not true on induced draft appliance.


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## jimbom (Jan 31, 2011)

I go vertical from the stove to a metalbestos flue.  I went to a pipeline supply yard and bought a 10 foot piece of steel pipe with a 0.20 inch thick wall.  This pipe extends up into the flue about three foot and fits tightly into the stove collar.  I was looking for something more substantial than the typical sheet metal stove pipe.  Also, having lived in earthquake zones, experiencing earthquakes, and now being at the edge of the New Madrid zone, I try to make things resistant to horizontal ground motion.  Especially things that may start fires.  It is a heavy load for the stove to bear, but I have a steel stove that seems to hold up well.  Not sure if a nice cast iron stove would work with this arrangement.  It is painted black and looks good.


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## Dave_1 (Jan 31, 2011)

woodsmaster said:
			
		

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Please explain further because;

after 30+ years our white ceiling looks as it did the first year. Initially I too used furnace cement to plug the gaps but the stuff would crumble. So after a few years of stuffing & no carbon monoxide alarm learned my worry was unfounded & give up on the furnace cement.

However, if woodmaster wants to seal his connections that 6" T ring will do the job & give him peace of mind since that seems to be what he desires.


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## woodsmaster (Jan 31, 2011)

Dave_1 said:
			
		

> woodsmaster said:
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My boiler as most gasifacation boilers has 2 fans that push air up the chimney and creates pressure. Any unsealed joint will leak. Like I said it is not necessary in a natural draft stove.


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## Dave_1 (Jan 31, 2011)

woodsmaster said:
			
		

> Dave_1 said:
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Ok, since boatboy was referring to his wood stove, & Webby & I addressed his issue, I fail to understand your post to me regarding my comment to his issue???


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## woodsmaster (Jan 31, 2011)

I was just making conversation. You asked for further explanation so I give one.


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## boatboy63 (Jan 31, 2011)

rusty,
No worry about losing room air. My house isn't that tight. What I was concerned with was losing draft from roof to the stove by what was leaking thru the pipe at either the seams or joints. Picture it this way...take a standard drinking straw, put a very small pinhole in it 2" from the bottom. Stick the bottom of the straw 1" into a glass of water (leaving pinhole 1" above water line) and suck on the other end. You will see that it takes a significantly larger amount of suction or "draft" on the top of the straw to pull the water up. I know we aren't pulling liquid thru the stove, but whenever there is a vacuum involved and a small leak in it somewhere, it will substancially reduce the vacuum "draft" being pulled thru the stove. With room temperature air being sucked into pipe from leaks, it is cooling the pipe and promoting the accumulation of creosote. Look how a minor vacuum leak on today's cars will cause a check engine light. 

I got a larger stove mat and installed it yesterday. In order to do this, stovepipe had to be pulled down and stove moved to get old mat out and new one in place. At the same time, we took the pipe outside and used a wire brush on the bench grinder to remove the old cracked Rutland stove cement that I had used at first to seal it. This stuff was better than nothing, but it is a mortar that does not flex when dry. With constant expansion and contraction from heating and cooling down of the pipe, the cement will crack. I looked at the Rutland high-temp silicone, but it is only rated for 450* continuous and 500* intermittant. I ended up getting a tube of Permatex Ultra Copper high-temp silicone from an auto supply ($6.99). It is rated at around 625* continuous and 700* intermittant. After cleaning the old cement, we painted the pipe with stove paint, reassembled the pipe assembly to the stove, and installed 3 small screws to each joint. We placed a small bead of silicone around all joints and seams (including the 24" seam of each section of pipe) and used a finger to smooth it into the seams. We allowed it to dry several hours and started a small kindling fire (125-150* at the pipe) to just help speed up the curing process. 

Before going to bed, we built a small fire and let it go overnight. Checked this morning and all is good. Sealer is cured and no visible signs of cracking. In some areas of where the pipes join together, there was nearly a 1/4" gap and the silicone filled it nicely. Outside temps have warmed up for a few days but are forcasted to get cold again by the end of the week. I should be able to tell a difference by then. I will be able to get stove temps back up and will check my pipe temps at top of stove and at bonnet going into ceiling. I was getting around a 75-100* temperature drop in that 5' long area before with my infrared thermometer. We will see if this has made a difference.

As for using clamps, it may work, but not sure considering 1 end of each pipe is tapered with a crimped edge. Still have the 24" seam running up each section of pipe to deal with. Also, I understand the problem with a forced draft boiler leaking smoke. My stove doesn't leak smoke, but instead, felt like it was sucking air into the pipes at the seams.


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## PARKBOY (Feb 1, 2011)

How about taking a hand full of powder and blowing it lightly by the gaps and watch and see if it is sucked into the gaps?


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## boatboy63 (Feb 1, 2011)

Parkboy,
Can't do it now since it has all been siliconed. Before the stove cement/mortar was first put in the seams/joints, I did do a similar smoke test with a cigarette. I did see evidence of it pulling smoke, but since the stove was hot, it was hard to continue. When the stove is hot, it and the pipe puts out enough heat that it will actually "draw" the smoke up beside the pipe at a good rate of speed. This is because hot air rises.


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## PARKBOY (Feb 1, 2011)

boatboy63 said:
			
		

> Parkboy,
> Can't do it now since it has all been siliconed. Before the stove cement/mortar was first put in the seams/joints, I did do a similar smoke test with a cigarette. I did see evidence of it pulling smoke, but since the stove was hot, it was hard to continue. When the stove is hot, it and the pipe puts out enough heat that it will actually "draw" the smoke up beside the pipe at a good rate of speed. This is because hot air rises.



What kind of silicone did you use to seal it up and how is it holding up to the heat?


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## boatboy63 (Feb 2, 2011)

Permatex Ultra Copper. For the most part, it is holding good. Does seem that on the lowest part of the pipe where it connects to the stove flange, seems to be wanting to pull off in 1 spot. None of what was put on the flange was actually pushed into the cracks. It was just squeezed from the tube and not tooled in. All the other joints were tooled in by finger and is in good shape. Has been in the 50's for the last couple days, but is supposed to start getting colder tomorrow. This should give us a chance to heat it up a little more and see how it goes.


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## bigbluebus (Feb 2, 2011)

boatboy63 said:
			
		

> Permatex Ultra Copper. For the most part, it is holding good. Does seem that on the lowest part of the pipe where it connects to the stove flange, seems to be wanting to pull off in 1 spot. None of what was put on the flange was actually pushed into the cracks. It was just squeezed from the tube and not tooled in. All the other joints were tooled in by finger and is in good shape. Has been in the 50's for the last couple days, but is supposed to start getting colder tomorrow. This should give us a chance to heat it up a little more and see how it goes.



I understand exactly your line of thinking.  I had the same concerns, I have about 14 ft of stove pipe inside the house from stove to ceiling, all in 2-ft sections and all with seams running lengthwise.  

When I first put this setup together, I sealed the joints with stove pipe the best I could but most of it has crumbled and fallen out; but when the new stove replaces the current Chinese POC Vogelzang, I'm going to use a solid steel pipe (no seams) instead, if I can find a supplier by the time the new stove arrives.  I figured a solid pipe will also be much safer in case of horizontal movement.  I've also heard that in a case of a flue fire, the seams in the stove pipe will actually blow out and come apart (definitely don't ever want that to happen to us).  I don't know if this is true, but I'd rather err on the safe side.


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## mhrischuk (Aug 10, 2011)

PARKBOY said:
			
		

> How about taking a hand full of powder and blowing it lightly by the gaps and watch and see if it is sucked into the gaps?



Light a match and blow it out next to the gap. See if it draws in the smoke. You can use a cigarette if you smoke.


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## Backwoods Savage (Aug 10, 2011)

I have always used furnace cement in the joints of the stovepipe. Yes, you can get by without doing it but I still feel it is good and the stuff really is cheap so we are not talking about a big deal here.


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## RustyShackleford (Aug 28, 2011)

webby3650 said:
			
		

> Sealing the pipe joints isn't going to hurt anything, we only use Elmers and I see no room for cement in the joints. Woodstoves put out tons of heat, try not to think it to death. ;-)


So you find that Elmer's pipe actually fits together ?   Here was my experience:

https://www.hearth.com/econtent/index.php/forums/viewthread/67805/


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