Inside Black Stove Pipe Air Leak Question

[SummerTyme]

I am asking a question about my new install and air leaks in the indoor black stove pipe.

Ok, so today I decided that I wanted to see if I could check the flue out for creosote build up this winter by taking the secondary burn baffles out and shining a flashlight up the flue and using a mirror to see up the flue. It did give me a fair view of the flue all the way to the chimney cap. So, I think that will work out ok for me to be able to check the flue throughout the winter as I go through the learning curve on my new EPA stove.

However, when I was looking up the flue with the mirror I noticed I could see some daylight around the joints on the inside of the black stove pipe in two places. This concerned me, so on further inspection I found that there are gaps on the joints right where the stove pipe seam is at the joint. The gap is approximately an 1 3/4” long and close to an 1/8” wide right at the seam. This is true on both joints on the stove pipe. Both joints have three screws each to hold the sections together. I am thinking that I should perhaps caulk these air leaks in the stove pipe up but am not sure what to use to caulk them.

What I have on hand is Meeco’s Hi-Temp Silicone Sealant (good for temperatures up to 500 degrees F) and I also have SBI High-Temp Silicone for sealing door caskets on stove doors (also good for temperatures up to 500 degrees F). Which one of these would work best or is there something else I should use? And is something rated for 500 degrees F good enough for the stove pipe?

 

[bholler]

neither of those will work and there is no need if it is open 1/8" just use another screw to close it a bit but it does not need to be sealed

 

[fossil]

If the stove pipe is properly installed (male crimped ends inserted downward into the female uncrimped ends), and the stove has good draft when burning, this condition of some gaps at the joints will cause you no problem whatever. When the stove is operating properly, the pressure inside the flue pipe is below that of the ambient in the room around the pipe, so any gaps will simply allow some room air to be drawn into the pipe and join the flue gas stream up and out to daylight. There will be no release of flue gases into the living space unless there is a back draft or some sort of major blockage that prevents proper draft. If the gaps bug you, the thing to fill them with is known as furnace cement and should be available at a local hardware store. Rick

 

[webby3650]

Replace that snap lock pipe with factory crimped or welded 22 gauge pipe. No more gaps in the joints! It fits together perfectly!

 

[webby3650]

Also, sealant rated for 500 is not gonna cut it for very long.

 

[BrotherBart]

Biggest problem with the gaps is the cool air sucked in through them will create a glazed creosote stripe from the gap up for a way. Found that out the hard way. I cured it by lining the female part of the pipe with furnace cement before inserting the male part.

Means not being able to take it apart. But if you have a straight shot to the sky then you won't be taking it apart anyway.

 

[BrotherBart]

Replace that snap lock pipe with factory crimped or welded 22 gauge pipe. No more gaps in the joints! It fits together perfectly!

You know something about installing it that I don't. Which is no surprise. But I still had to "butter" the joints in the 22 gauge factory welded stuff.

 

[webby3650]

You know something about installing it that I don't. Which is no surprise. But I still had to "butter" the joints in the 22 gauge factory welded stuff.

Some is better than others. SBI makes some really nice welded pipe! They even make an insert for the female end of the slip sections that makes a nice tight fit, but in turn, still slips easily after the insert is lifted up.

 

[BrotherBart]

Good to know. I used the Simpson stuff.

 

[SummerTyme]

I don't plan to fire the stove up until temps get into the 40's. The directions for the furnace cement says to let the cement set for an hour and then heat gradually. So is it ok to use the cement to fill in the cracks now while its still summer and I'm not going to fire up the stove right away?

 

[webby3650]

I don't plan to fire the stove up until temps get into the 40's. The directions for the furnace cement says to let the cement set for an hour and then heat gradually. So is it ok to use the cement to fill in the cracks now while its still summer and I'm not going to fire up the stove right away?

Unless you break the pipe down and seal the joints as you put it together, it will do almost no good and it will look really bad all over the pipe. Either way, I find that it just dries out and falls out anyway due to the expansion and contraction of the pipe. Since it bothers you, do yourself a huge favor and get some welded seam pipe.

 

[BrotherBart]

The heating instructions are to boil the moisture out of the furnace cement. Which will happen whenever you get around to firing the stove. But webby3650 is right. Don't slather the stuff on the outside of the joints. Butt ugly and will just fall off.

 

[BrotherBart]

Burn it for a season and when you clean the chimney next year use that mirror and see if you see any shiny stuff. Don't go solving a problem that you don't have yet.

 

[SummerTyme]

Burn it for a season and when you clean the chimney next year use that mirror and see if you see any shiny stuff. Don't go solving a problem that you don't have yet.

Well, you may be right that I'm trying to solve a problem I don't have as of yet. However, in the past with my old stove I did get some back drafting problems with high winds and smoke would come out the pipe joints. While I don't know if I will have the same back drafting issue with the new stove, I do want an air tight flue.

I'm wondering what if I just stuffed a piece of replacement window gasket material in the cracks...would that seal it up? I would think gasket material would take high temperatures ok.

 

[BrotherBart]

I'm wondering what if I just stuffed a piece of replacement window gasket material in the cracks...would that seal it up? I would think gasket material would take high temperatures ok.

It worked for me. Just wasn't gonna mention it. Stuff is good to at least 1,400 degrees.

 

[begreen]

Some is better than others. SBI makes some really nice welded pipe! They even make an insert for the female end of the slip sections that makes a nice tight fit, but in turn, still slips easily after the insert is lifted up.

I first saw the SBI pipe this spring and was impressed. It's a nice system.

 

[BCC_Burner]

Is the SBI pipe available online anywhere? I was looking at their heat shields for single walled pipe and they seem to be one of the few companies that makes a 45 degree heat shield. Would love a lead on tracking the stuff down, as purchasing any sort of wood burning accessory in a brick and mortar store is a nightmare around here.