Flue hairline crack?

[articcatbill]

I was getting ready to clean my flue today and noticed what appears to be a hairline crack in my flue liner running vertically down the tile. It is an external flue, where this is it is about 2-3 feet below grade. It is right inside my thimble on the back side of the flue.

I am thinking that it is a crack, but what it odd is I can't even catch a finger nail on it. Yea I know I have a bit more cleaning to do, I took the pic when I first removed the pipe from the thimble when I was getting ready to clean.

It is really tight, like I said can't even catch my fingernail on it.

Thoughts?

Since I can get to it could I seal it with some refactory cement? or high temp silicone?

Is it something to worry about?

I could reline with a stainless steel insulated liner which would help with stack temps and the external flue. If I can avoid that safely I would prefer avoiding it for now.

Any help appreciated, thanks!

 

[bholler]

Absolutely a vertical and horizontal crack there. And chances are you probably have more cracks elsewhere in the liner as well. You can have it scanned to confirm that if you want but those cracks alone is enough to call for a new liner.

 

[BrotherBart]

If you can't get a fingernail in it, ya ain't gonna get furnace cement in it. And since that is obviously right where the exhaust blasts into the tile silicone is totally out of the question. It goes "poof" at 800 degrees. With that much stage 3 creosote that close to where the exhaust is burning off just that spot, I would hate to see what the rest of the chimney looks like.

Get that stuff scrubbed out of that flue and line it. Do not line it with that stuff still in there.

 

[articcatbill]

Thanks for the replies, oddly enough the rest of the flue cleaned up nicely. The top part is fine. Most of the stage 3 was around the thimble and lower. It was clean when I brushed it mid-winter. I picked that up from mid-winter to spring. Been burning wood for 20 years, never really had that issue before. Late winter was mild and wet, so sure I wasn't burning it hard enough.

I don't think that is a horizontal crack, just the vertical one, I see what your referring to, might just be the picture. I will check that tomorrow though to be sure.

Again thanks for the feedback.

 

[bholler]

I don't think that is a horizontal crack, just the vertical one, I see what your referring to, might just be the picture. I will check that tomorrow though to be sure.

I could be wrong but it sure looks like one to me. But regardless even if it is just that one crack it is enough to call for a new liner. There really is no way to fix it and it may be tight now but it is not when the liner gets heated up.

 

[articcatbill]

So I got the flue cleaned up a bit today, found another vertical crack in the same tile in the liner as well you are correct bholler that was additionally a horizontal crack. The vertical cracks do extend into the tile below. I attached a picture below. So I have to move forward and get this corrected. I have a few questions that maybe someone can help with.

First of all how much will an insulated flexible liner help with my draft? The reason I ask is this, my house sits at the bottom of a steep hill, surrounded by tall trees, I have an external flue on the one story part of a split level house. So basically was put in the worst place possible. It is really hard to get the flue warmed and a good fire going, once I get it going it burns OK. I am wondering how much the insulated liner would help, or will I always be battling the draft due to my location and the flue location.

I have been thinking that someday I might like to switch to a pellet stove. I still don't mind processing wood, but the day will come I don't want to deal with it anymore. We moved about 3 years ago and generally now have to buy wood, although I have had a lot of ash given to me lately. So my thought is do I cut my losses quit battling the draft and put in a pellet stove now. Would still need a liner but only a 3 or 4 inch. Would a pellet stove vented through the masonry flue with a liner take care of my draft issues?

If I put a liner in for my current stove now, (my flue is 11x7), would I then have to turn around and put in a smaller one to accommodate a pellet stove later if I go that route?

What makes this hard is I currently have 2-3 years of wood in the yard seasoning. I was switching in my kodiak woodstove to replace a locally built one that was in the house when we bought it. So I re-bricked it, re-painted it, new pipes and am having a new baffle built. So thought that I was all good to go for the winter, and then found this. Oh well that's life. So my decision is, do a pellet stove now, or put a liner in to accommodate my kodiak and keep burning wood. Any thoughts?

 

[bholler]

First of all how much will an insulated flexible liner help with my draft? The reason I ask is this, my house sits at the bottom of a steep hill, surrounded by tall trees, I have an external flue on the one story part of a split level house. So basically was put in the worst place possible. It is really hard to get the flue warmed and a good fire going, once I get it going it burns OK. I am wondering how much the insulated liner would help, or will I always be battling the draft due to my location and the flue location.

You will be amazed by the difference. It will heat up much faster and it will respond when you adjust the air much faster as well.

Would a pellet stove vented through the masonry flue with a liner take care of my draft issues?

Yes but a liner will take care of your issues for your stove as well

If I put a liner in for my current stove now, (my flue is 11x7), would I then have to turn around and put in a smaller one to accommodate a pellet stove later if I go that route?

It may work of with a pellet stove. If not a 4" liner does not cost much at all.

 

[mellow]

my flue is 11x7

Eeek, that non-epa stove is going to want an 8" liner and it needs to be insulated, how tall is your chimney?

 

[articcatbill]

It is 18 feet from the top of the flue to the middle of the thimble. Since I have a 11x7 I can't get a round 8" in there. So I think that I am going to have to go square to get what i need for the stove. What would be the square equivalent to get 8"? I also want it insulated. I don't think an oval would give me what I need.

Using some of the calculators 8" = 50 sq In cross section. Looks like i need to go rectangular to get what I need and have room for insulation. 5.5x9.43 (46.4) is close and gives me 2" for insulation.

How much room would I need to leave for insulation?

Using Rockford just to price out components quickly it looks like 1800 for this sizing.

Am I thinking right here? Does that sound in the ball park?

Got a ballpark quote from a local reputable company of 2500, which seems in line with what I am seeing for buying the components myself.

Having an idea on this will help me with my decision.

Thanks for all the help out here!!

 

[mellow]

Get a quote on busting out the terracotta then you might have room to run an insulated round 8" down it.

 

[articcatbill]

Get a quote on busting out the terracotta then you might have room to run an insulated round 8" down it.

Thanks for the idea mellow, I got a quote on that, it was much more reasonable for sure, 1200-1400 range.

In the end we weighed everything out and bought a pellet stove. Got a P68 Harman, just going to have the dealer do the install and also clean the flue.

One factor in this was since we moved I no longer have access to free wood. Where I previously lived my neighbor let me cut all the wood I wanted. I would cut-up tops after he would have sections timbered. I enjoyed jumping on the quad with a trailer and cutting a trailer load. I no longer have that luxury and would end up buying wood and processing it. Just decided if I was going to have to buy wood I would buy pellets instead. I knew at some point in the future I was going to move away from wood, might as well save the cost of a liner for the wood stove and move to a pellet stove now rather than later. Had a great 20 year run cutting, splitting and burning wood. Time to give something else a try.

Thanks to all for the suggestions and help as I worked through the situation. Very much appreciated.