Hi Sierra, I was unable to open your attached photo for some...

Hi Sierra, I was unable to open your attached photo for some reason to view the cowl arrangements you describe.

My wood heater cowl was the same as the one in the photo, it was quiet flimsy and spot welded onto the adaptor which slipped strait into the flue. It was a very tight fit and I was unable to extract it without twisting it out of shape which basically shagged it and made it unusable. I did consider at the time it was more bother than it was worth and especially when running the cleaning brush through the flue so didn't fit anything else and left it open.



The outer skin covering the flue is approx. 250 mm dia. and is made from galv iron sheeting bent up to form the tube shape. It doesn't have any insulating material and just relies on the air gap between the 2 surfaces. This outer skin is connected to an adaptor plate that runs through the ceiling surfaces (inner and outer)   and has a corrugated base that suits the roofing iron profile.

We also have a lot of trouble with possums on the roof of a night, the little buggers seem to be able to climb anything. We do run our drinking & cooking water through a filter arrangement to ensure it is mostly clean for drinking in hope that it takes the crap out.