I am installing a Keystoker boiler in a insulated shed and plan to exhaust it via metal pipe up through the roof. While pricing insulated double wall stainless pipe today, the man behind the counter said I'd be lucky to get a few years use out the stainless and even less from galvanized due to the highly corrosive property of coal gas.
Is this how it really is? And if it is, can it be slowed down.
Also my boiler has an 8" outlet flange. Is it OK to reduce to 7" at the double wall? The manual says reduce at the thimble and I assume a reduction at the double wall as it goes through the ceiling and roof would be acceptable.
Thank you for your thoughts
Keep it 8" all of the way out, especially with a short chimney.
There are various grades of stainless. The 400 series is a cheap stainless that some chimneys are made of. Stay away from this for the inner liner. Ok for the outer liner.
316L is the best choice for an inner liner for coal.
Olympia has the best warrenty for coal.http://www.olympiachimney.com/products/cat/VCAA/
I used amish chimney made from 304 ss. I didn't know about Olympia at the time. My chimney on the keystoker looks ok after 1 year. Keeping it dry on the inside and brushing the ash out after the season is a must.