close fit rigid mock up system?

[sauer]

I got a interior 12x8 OD, 11.5x7.5 id terracotta lined masonry chimney with a very mild bend in it. If I look directly up the chimney I can see 3/4 or 7/8's of the cap. I would like to use a rigid liner because I cannot insulate a flex with my small ID of the chimney, and it is only 14 ft wich is min for a woodstock fireview. I believe duraliners OD of the rigid is 6.25. I did the paint can test with no problems. I was thinking of buyng some cheap 6'' heating ducts to see if it will go down with no restrictions, I could always return it if I dont scuff it up to bad. My question is if anyone has any ideas if I could mock up something to see if it will go down there other than buying heating ducts? I have been going back and forth a million times on what I think is the best venting solution and there is always one or two hangups. It took me 2 months just to get to where I am in the project with countless research and phone calls to tech lines. A tech told me that my chinmey doesnt meet codes because my chimney doesnt have 2'' airspace to cumbustables, another tech said I am ok because of the airspace between the terracotta and the ss flex and also between the clay and the cinder block(1'') and the block to cumbustables(1''). I dont know who to listen to but I would like to go the safe route. Any suggestions on a close fit mock up system for rigid liner?

thanks all.

 

[BrotherBart]

I don't remember the exact diameter but a empty paint can is something like 6 3/4". I lower one down on a rope to check to see if a liner will fit.

 

[sauer]

A flex liner will fit no prob, without insulation. I already did the paint can test and she went right down. Its the mild bend and me wanting the best drafting, safest exausting (rigid)pipe.

 

[theheatelement]

rule of thumb... liner and rigid are normally both 6" inside diameter. For flex add 3/8" for outside diameter and for rigid it is simply the gauge of pipe.. Most rigid pipe is 24 gauge or .024 so it would be 6.048

 

[sauer]

I was wanting to go with the duraflex insulated rigid If I cant Ill have to do the flex.

 

[Todd]

If it don't fit maybe you could go with this? http://www.dynamitebuys.com/store/cart.php?m=product_detail&p=1275
Begreen posted this insulated oval liner in another thread and might be the ticket for those tight fits? Wonder if there is a chimney brush for them or if you have to make one? Another option is 5.5" flex, works great for my Fireview setup.

 

[sauer]

the ovalized liner would not work because clearances are close on the with side (11.5) due to the slight bend of the chimney. talked to woodstock and they didnt recomend the 5.5 due to drafting issues. Its one of thoes deals where I believe that 6'' rigid liner will fit but its not a given and I dont want to spend the cash on the liner to find out it binds down the chimney. the chimney doesnt bend by any means but it is not totally straight up and down it almost looks like the tiles shifted or slightly offset. there is plenty of room from side to side if the chimney was straight but with the slight offset I would like to make shure before I pull the trigger on the chimney liner. I would assume if when I dropped the paint can down slowly and it didnt touch any of the sides I was concerned about on the way down I probibly would be golden.