A 6 inch round flue exhaust is 28.27 sq inch , an 8 by 12 inch flue is 96 sq inch. wood is easy to exhaust because of heat, coal not so easy. I think you are really pushing the envelope with an 8 by 12 flue; unless your chimney is in excess of 16 ft from thimble to top.
Jim
Draft
- SWPaDon
- Member
- Posts: 9857
- Joined: Sun. Nov. 24, 2013 12:05 pm
- Location: Southwest Pa.
- Hand Fed Coal Furnace: Clayton 1600M
- Coal Size/Type: Bituminous
- Other Heating: Oil furnace
I made one out of 12 gauge galvanized 17 years ago for my chimney. It's still there. I'm burning wood and Bit coal though..........Anthracite mileage may vary, I dunno.Lightning wrote:Ahhh yes.. in this case the cap was likely the issue. I should have spoken up earlier but thought you were a new coal burner.
I had a cheap chimney cap the first couple years. I noticed that it didn't look right last summer. I went to the roof and found that the wire cage had disintegrated and the cap was starting to collapse onto the chimney, closing it off. I since bought a higher end cap made of stainless steel. It still looks shiny.