Guys, and gals, i have a single walled flue pipe as a chimney and i suffered radial cracking from the chimney area back over the dome. Now, i'm sorta thinking that this could have been from the expansion of the flue. As i have some frost induced repair work due, i think i may change to some 6" Internal Stainless Twin walled, insulated flue.
Does the 6" Internal still give good draw? I'm currently at 8". I expect it'll be a little less, but probably negligable.
Have you guys still suffered cracking out from your flues where you have got Twin Walled flues?
I'm hoping that the twin wall will insulate enough to keep the expansion down to what the render/mortar can handle, keeping the water out and preventing further spring repairs.
where the flue enters is an area for water to penetrate and then crack when heated to steam so I think its very hard to not get some movement here, I have a crack from my twin wall flue but I am sure I did not do the best render job in the world. I have a 6" flue and seems to draw well when going, I think the benefit of the twin wall is the inner liner heats up quicker to get a good draw.
it is hard to say if it is enough for my 32" oven but I think so, it allows me to get up to the top clean burn ok, I would also think a smaller diameter will give more draw as gas will travel up it quicker to a point?