Why a "kink" in my masonary chimney

[Jerry_NJ]

I have a 25 year old house with a set of three chimneys in a stand-alone brick (with block foundation) structure that my house connects to on one end to provide a fireplace in the living room, another in the master bedroom, on second floor, and a flue access for a stove, in the basement.

I had a Quadrafire insert installed in the living room fireplace last Thursday and the installer had some difficulty getting the Duraflex 6" line to make it around a "kink" . After no success in pushing the liner down from the roof, he had two guys on the roof, he pulled the liner back out to the roof and tied a wrench (weight) to the input end of the liner. Then going down again to the living room, he used the wrench and then rope to pull the liner while the guys up on the roof pushed. Even with the pull it took several tries to get the liner around the "kink".

I'll describe the kink this way: laying on my back in the living room fireplace and looking up the chimney, feet sticking into the living room, I can see the flue/chimney above the smoke shelf bends outward, away from the house, sufficiently that I can't see above that section. I estimate the outward path is about 30 degrees off the vertical. I was told, I don't go in the roof myself, that looking down the chimney there is well down the length, clearly in the neighborhood of the outward swing that can be seen from the living room, there is an outward swing. This leads me to conclude this fireplace design called for a kink in the flue above the smoke shelf for some fireplace reason other than it had to go around something, there is nothing in the way (or is there?). My main reason for posting this thread is to try to locate a fireplace "architect" that would know if there is a design that calls for such a kink...maybe it helps regulate the draft, this is a chimney that is over 30' tall. Or maybe the kink provides some reduction in lost of heat when the damper is open...or perhaps it is there to help collect creosote that the sweep can't see (we have had some odor problems with this fireplace in recent years.) I do note too that even though the fireplace was swept and roto-cleaned (power cleaned) this spring, when the installer "horsed" the new liner around the kink a lot of soot and black junk came falling down.

 

[jtp10181]

So does it go out and them come back again? Like there are two offsets?

Otherwise if it is just a single 30 deg offset, that is very common.

 

[Jerry_NJ]

jtp, thanks, I can't say for sure, but if an offset of about 30 degrees that simply then straightens out is common, that is probably what it is. Still it seems the trouble the install had suggests something more difficult. But, I've learned the Duraflex liner is much stiffer than, say, a Homesaver UltraPro (which is what I contracted for, I got an substitution - unwanted and less expensive, subject of another thread that BrotherBart has been very helpful on) and that may be the reason it took so much push/pull to get it around the two 30 degree bends...hum I can picture that, the liner comes down, hits the 30 degree turn toward the house, and before it goes very far, it has to turn back 30 degrees to return to a vertical down run. It may have been difficult to make the liner make both turns. I was watching and can say when the boss, in the living room, pulled on the rope there was some movement and then a stop, then some more tugging and more movement and the liner appears, that could be the second turn that returned the run to the vertical again. This should not be too much stress on the liner, it was just hard to get it to turn, even one (each) corner.

Do you have a knowledge of why this jog would be put in th flue? I can't think of any function, but then I'm not a fluid/gas dynamics expert. I do feel better knowing/believing the liner has only to make two bends on its way to the Insert. This too shouldn't cause any problems when cleaning with a brush fed up from the stove, that isn't asking too much flex on the cleaning poles.

Note there are two edits in the above, if you read before the edits you may find the text now easier to read. Must be getting tired.

 

[jtp10181]

We use the simpson duraflex also. Works good. Sometimes those bends can be quite the trick. We have one out there I know of that almost goes horizontal before heading up the flue. It still works fine. Only reason I can think of for the bends would be if there is also a boiler flue in there. They built that and then offset the fireplace flue so it goes next to it. Other than that I have no idea.