Chimney/woodstove question

[SwampDonkey]

That's what I thought you were talking about. I couldn't imagine it any other way. That is fine. It would be no different than the old clay liner system.  I think the trouble is air flow around the outside of that new liner, between it and the flu walls. Creasote buildup on those cool walls. See if they insulated it down to the thimble by the stove pipe.

[Holmes]

John Mc is correct the open end must be capped. The flue is sucking air from everplace except the stove , the path of least resistance is the open tee.

[tyb525]

They didn't insulate it at all, which seems to be the problem, along with the open T. :-\ We'll be contacting them I'm sure.

[SwampDonkey]

Another question here, is your flu higher than the peak of the house? The flu has to be the tallest structure for good draft.

Maybe the top plate on the flu up top isn't installed properly.

Here is a site to have a look at with chimney liners.

http://askthechimneysweep.com/2009/08/installing-a-flexible-stainless-steel-chimney-liner

[Don_Papenburg]

Doubling the dia. of pipe increases the volume four times .  a larger pipe will slow the velosity of the gasses.  so if the stove is 6" the flue also should be 6" no more than 8" .

I think that the open bottom T is making the draft problem .  How hard will it be to plug that hole .  Basicly that would be cutting you stove gas exhaust draft in half .  The hot gas is pulling the cold air up with it .  50/50 mix? maybe .  so that drops stove volume almost 50% .
But then you have the cooling effect also . that drops the speed of the flue gas as it cools.  that might be putting you at only 75% of normal volume.

[SwampDonkey]

I don't know how your going to clean that flu when bottom is capped off and how the heck are you going to deal with taking it off to clean the flu? What happens when that bottom end gets full of creasote and soot? I think insulating the liner, checking the cap to see that it's sealed on there, and also flu height if it isn't above the peak, which at this point I don't know.

[Holmes]

I don't know how your going to clean that flu when bottom is capped off and how the heck are you going to deal with taking it off to clean the flu? What happens when that bottom end gets full of creasote and soot? I think insulating the liner, checking the cap to see that it's sealed on there, and also flu height if it isn't above the peak, which at this point I don't know.

The bottom of the tee could be run to the cleanout door then capped. The top of the old flue shall be sealed off with metal and the liner shall pass thru it. Now the space in the chimney between  the liner and the flue can act as an insulated chamber. Insulating the pipe would be better ,but the old flue must be capped off. You still need to cap the open tee. Holmes

[SwampDonkey]

My understanding with the top sealed/caulked as it should be, is it can't suck air down and in the bottom of that open end of the T. And that section into the thimble of the flu to the stovepipe needs sealing off so it don't suck air in from the room from that open end.

[Holmes]

My understanding with the top sealed/caulked as it should be, is it can't suck air down and in the bottom of that open end of the T. And that section into the thimble of the flu to the stovepipe needs sealing off so it don't suck air in from the room from that open end.

That is correct.I would still like to see the tee capped off. The old flue could have air getting into it thru fractures, the cleanout door , and around the flue pipe. Holmes

[beenthere]

Holmes
You have the right solution to solve the problem.

[John Mc]

I still may not be picturing this correctly. Your T is inside the chimney, allowing the creosote to drop to the bottom of the cleanout, where you can reach it by opening the door?

This might work OK without capping the T, if the door seals well when closed, and all other openings are blocked (the top of the chimney, the thimble where it connects to the stove). Basically, you don't want to draw any air in through the open end of the T. You can do this by capping off the T, or blocking off any sources of air getting to the open end of the T.

However, as I think about your situation further, I don't know how you can block off the other air sources. The obvious ones are fairly straightforward - the top of the chimney between the old 12" flue and the new liner, the thimble, and the clean-out door. The problem is that the new liner was put in because there were problems with the old one after the chimney fire. The old 12" one most likely has some leaks somewhere along its length (otherwise, why put in a new liner?). You are not going to be able to plug those. This will cause 2 problems: 1) it allows in air to the space between the 12" and the new 6" flues, providing a source of air to the open end of your T. and 2) the cooler air being drawn in through the cracks in the chimney/12" flue will cool your uninsulated 6" flue, causeing further draft problems and creosote formation.

All this leave me thinking you do need to cap that open T. Perhaps you can extend it downward so the cap is easily reachable from the clean-out door? This would make it easy to remove when cleaning the flue. However, that this is probably just a start towards resolving the problem -- though it may be a good start.

I have to wonder if the guys who installed this had any idea what they were doing? An uninsulated metal flue inside a much larger flue with multiple paths for air to enter the space between the two, and an open T into the new flue??

One thought: When my parents renovated the kitchen in an old farmhouse after a kitchen fire, they decided to add a small fireplace. They wanted to tap into an old, unused chimney. The flue was in bad shape. The could not fit a round flue of the size required into the opening (they had more than enough cross sectional area, but it was in the wrong shape). They found someone who put something down the chimney as a form, then poured some sort of material (castable?) to fill the gap between the form and the old flue. Basically, they poured a new flue liner in place. I wish I could be more specific, but I wasn't around when this was done. It sounds as though something similar might work in your situation?

John Mc

[SwampDonkey]

It will help the draft with that cap, no question. I just hope you can extend that T to the cleanout and then be able to get it off to clean when the creasote seals it nice and tight. I don't know that  a little air through the masonry is all that big a deal, but it may prove to be.

[tyb525]

SD, the top of the chimney is 3 feet higher than anything else on the house.

Extending the T down to the cleanout door should work, and I believe it would be accessible that way. I'm pretty sure I could make a simple cap that would be easily removable, and a cap for the top to seal it off, also.

[SwampDonkey]

Good on you Tyb, because I didn't know how easy it was going to be to add an extension on and cap the bottom by the cleanout. I wouldn't be able to do it through my cleanout and most I've seen don't have a very big opening to work from. You should be able to get a cap for the top from the stove store and make sure it's sealed onto the old flu brick with some caulking. Three feet is lots of height. I didn't know if that was part of the problem because you had a huge 12" flu there for air before, now 6".

[Holmes]

 Tyb It sounds like your chimney guys have a lack of experience.  A cover for the top of the flue  and a cap for the new liner should have come with the liner kit. More important is to find out if the liner is stainless steel, it is supposed to be, no it has to be SS. If it is aluminum it will burn up with a chimney fire. Holmes

[SwampDonkey]

Holmes I think it was the flexible stainless, Tyb will know.

[tyb525]

Yeah it is stainless steel, I have a scrap piece a few feet long sitting in the barn. If it was aluminum, I'd be about ready to sue those guys and reline it myself :D

Thanks for your help guys, I knew one of you a whole bunch of you would have some good knowledge on the subject

[Handy Andy]

  I haven't been with this thread the whole time, just read through some of it yesterday, but reminded me of building my house. I built the house, but hired a mason to lay brick and build my chimney, for wood stove.  I told the guy while he was doing the chimney, I'd like to have the gap between the liner and the block and bricks filled in solid, and he said what with?, so I just started carrying 5 gallon buckets of fill sand over, and putting the bucket on the scaffold.  Well, he just dumped them in, and my chimney is filled right to the top with sand.  Wouldn't have to worry about a chimney fire if you had it filled with sand, would you?  Wonder why you couldn't just knock a hole in the top of the chimney where it is sealed up with concrete and dump sand down into it till you get  it filled in? And of course, fill the top in with concrete.  Then you could just take that nasty restricting pipe out.

[beenthere]

I don't think I would want the weight and the pressure of a chimney filled with sand (around the liner).
I think there would be too much outward load on the chimney brick and block. In time, I think it will settle and seek a way out.

But hopefully didn't happen and never will.

[John Mc]

If I'm following the OP's description correctly, that sand would just flow down and fill up his cleanout as well. Might be OK on a chimney & installation designed with that in mind, but I'm not sure how well that would work here.

[Handy Andy]

  My chimney has a cleanout at the basement floor, the flue liner is sitting on 4" block up to where the stove hooks onto the liner, and always thought I'd get a bit of sand leaking into it, but never have. It's 30 years old now.