Dampner question

[jgcable]

My masonary chimney has a dampner that basically splits my fireplace flue in half when its open. The bar runs directly across the middle of the flue. I am ordering a 3" flex SS liner for my new pellet stove insert and it doesn't appear the 3' diameter flex pipe will fit in the space inbetween the dampner and the flue wall. I read articles online showing how to ovalize the liner but if I do that it won't be round at the end where I have to connect it to my stove. I am also concerned abou constricting the pipe so much. What to most guys do? Do I remove the dampner assembly (I don't even know if I could). This must be a common question although I can't find any threads on it.
I am trying to figure out what the actual diameter of the 3" flexpipe is. Is it 3" ID or 3" OD? I haven't ordered it yet so what I would like to do is go to the local Home Depot and pick up a piece of pipe that is the same diameter and test fit it.
Thanks...

 

[IceNine]

is there a fireplace at the bottom of that chimney? usually that slab is there to create negative pressure for smoke and stop some of the blowback. Guessing if you're running a liner this is a permanent solution so personally i would just take it out/break it, whatever.

 

[jgcable]

Actually.. the bottom of the chimney is in the basement and that is where my gas furnace, hot water heater are piped in. There is also a clean out in the basement because the floor of my fireplace has a hinged trap door in it for the ash.
My fireplace (where the new pellet stove insert is) is on my first floor. I have a large brick fireplace and there is a brass handle sticking out of the front of it 37" from the floor. This is the handle for the flue dampner. It basically looks like a carburetor choke if you look up at it from the fireplace floor. It runs directly across the flue and when its open it splits the flue in half. It is a very heavy duty looking assembly. I would hate to have to break it to remove it. Its possible the the 3" flexpipe I am getting will fit but its hard to guestimate without actually having it. I have to order it online.

 

[DAKSY]

Can you post a pic of your damper set-up?
You should be able to disable the mechanism
& drop the door out of the way so your liner will clear.
If the mechanism is dead-center, just run your liner to
either side of it & then back to the middle to hook up.
This DOES make your block off plate a little
more challenging to fab up, but it'll still work...

 

[jgcable]

Can you post a pic of your damper set-up?
You should be able to disable the mechanism
& drop the door out of the way so your liner will clear.
If the mechanism is dead-center, just run your liner to
either side of it & then back to the middle to hook up.
This DOES make your block off plate a little
more challenging to fab up, but it'll still work...

According to my owners manual it specifically states to not use a block off plate so all I have to worry about is getting past the dampner plate which is runnign dead center in my flue. There might be enough room on either side but its hard to tell without the liner in hand.