Up sizing a Metalbestos chimney

If a stove/boiler has a 6 inch outlet is it generally considered a problem if an 8" chimney is installed? (I know going from 8 to 6 would be a bad idea).

If a stove/boiler has a 6 inch outlet is it generally considered a problem if an 8†chimney is installed? (I know going from 8 to 6 would be a bad idea).

When I did the research for my project I found it was not a problem to go from a 6" flue out of the boiler and increase it to an 8". Most did not want you to decrease it from 8" to 6". It seems like one company told me it would not be a problem if I reduced as long as the draft of the chimney was strong enough. But I would not reduce if I was you. The increase seemed to be fine. My existing chimney was 6" and my Wood Gun has a 6" as well. Good luck. And keep us posted.