hey all, in my shop i will have two coal forges, i think side draft hoods are better than a canopy style, but i am wondering if i can put the two hoods back to back and use the same chimney for both? the pipe size will be 12". or would it be better to put a long canopy style hood over both forges using the same chimney?

i am trying not to put two holes in my roof. matto

Usually shared chimneys are not recommended.

12 inch diameter is 113 square inches. Double that would be 226 square inches. One 18 inch diameter chimney is 254 square inches. One forge in a 18 inch chimney did not draw will for my side draft set up.

If you are running the forges back to back why not just run two 12 in chimneys side by side? It would be just one 12 x 24 inch hole in the roof.

i am thinking that is what i am going to do. i do prefer the side draft hood over a canopy.

Will both be in use at the same time? If not you can share the flue and use a blocking plate on the unused side.