True Heat TH36PA Fireplace 8" ID x 14" OD chimney extension

[abqgolfer]

I am wanting to add a section of chimney to my existing roofstack. This is my parents house that was built in the mid 80s. The fireplace has a label Dhat shows this to be a TrueHeat TH36PA zero clearance fireplace. The manuals I found online call for duct pipe that is 8 inches innner diameter and 14 inches outer diameter. The manual lists these sections as F36-8 which I take to mean 36 inches long by 8 inches ID.

I cannot find this type of ductwork. The inner 8" piece looks separate from the outer 14" and is just centered by tabs that are riveted to the outer duct but are not attached to the inner duct. The inner 8" duct reminds me a single wall Duravent where it just has a buldging rib about 1 inch in from the end that keeps a mating section from falling over it when connected. The outer 14" duct reminds me of typical hvac duct but I don't see anything like snaplok it looks more fabricated and then they riveted tabs to keep the inner duct centered. The rivets look like a manufacuterers rivet not something that is home owner style.

I am looking for a way to find a solution for adding another 36 inch section to the top but have not seen anything close.

Any pertinent kind help would be appreciated.

 

[DAKSY]

Talk to a local sheet metal shop. They can probably fabricate what you need.