Chimney Insulation on WFO?

[Madsen]

Hi all,

I'm in the planning phase of my WFO, i'm atm doing alot of excavating, about 35 tons of dirt needs to be removed to form the hole where i want my WFO to be in. 13 by 20 foot hole.

Well the question I have right now is something I find hard to locate any direct opinion about in the forum. The chimney, I'm gonna make about ?6-8" and then about 40-50 " tall.

Is a normal stainless steel or just steel tube sufficient, or should there be some insulation to make the draft better ?

Its just because I calculate that I'm going to go over and above my budget, so I'd like to cut some corners somewhere - But it cannot compromise the end result

I'm living in Denmark, where the temp is not going above 30 degrease Celsius in the summer. The average temp is about 20 degrease Celsius in the summer (where I plan to use the WFO)

Hope you guys can share the knowledge and maybe help clarify for me.

EDIT: I'm using the 42" plans from this forum. with same dims etc.

Thanks.

[david s]

Re: Chimney Insulation on WFO?

The required diameter of the chimney depends on the volume of the oven chamber. Your planned height is about normal. Higher gives you some more draw.What kind of oven are you planning to build? Hemisphere, Barrel oval? What internal dimensions?

[Madsen]

Re: Chimney Insulation on WFO?

The required diameter of the chimney depends on the volume of the oven chamber. Your planned height is about normal. Higher gives you some more draw.What kind of oven are you planning to build? Hemisphere, Barrel oval? What internal dimensions?

Hi David,

I just edited OP, but I'm making the pompeii 42" according to the plans on Forno Bravo.

[boerwarrior]

Re: Chimney Insulation on WFO?

The reason that Stainless Steel is used is that it won't rust. Regular steel will probably last a long time but will begin to deteriorate slowly - but it may still outlive your oven. My chimney is stainless steel so I can't comment on how regular steel would work. I know that many on this forum recommend NOT using galvanized due to the potentially dangerous gases being burnt off by the heat.

You do NOT need to insulate the chimney. Mine is not insulated and draws perfectly.

Good luck!
Neil

[stonecutter]

Re: Chimney Insulation on WFO?

Galvanized steel flue will rust away relatively quickly.

[texman]

Re: Chimney Insulation on WFO?

If your oven will be uncovered the steel chimney will definitely rust and the rust will become brick stain over time. just saying' Get some stainless, you not regret it.

Texman

[Madsen]

Re: Chimney Insulation on WFO?

Thanks guys, i'm going to get a stainless steel with no insulation of any kind. That should save me some money for sure

[david s]

Re: Chimney Insulation on WFO?

The required diameter of the chimney depends on the volume of the oven chamber. Your planned height is about normal. Higher gives you some more draw.What kind of oven are you planning to build? Hemisphere, Barrel oval? What internal dimensions?

For a 42" Pompeii you need an8" diam flue pipe.

[stonecutter]

Re: Chimney Insulation on WFO?

8" minimum.

[wotavidone]

Re: Chimney Insulation on WFO?

I'm unfamiliar with countries that have snow in the winter, so I'm unsure whether what I propose is viable, maybe freezing and thawing is no good for bricks and mortar. However, if you are short of cash, can you find enough secondhand/free bricks to make a brick chimney?

[stonecutter]

Re: Chimney Insulation on WFO?

I'm unfamiliar with countries that have snow in the winter, so I'm unsure whether what I propose is viable, maybe freezing and thawing is no good for bricks and mortar. However, if you are short of cash, can you find enough secondhand/free bricks to make a brick chimney?

Yep, freeze/thaw = rough on masonry work. There is plenty of masonry done in that climate, but it better be done with best practice through the whole process. Outside of a major event like an earthquake or a truck driving into your work, nothing is more damaging to masonry than freeze/thaw.

If you mean build the flue out of brick, then no, it's not a good idea. Clay flue with a brick surround is the way to go if he doesn't use SS.

[Madsen]

Re: Chimney Insulation on WFO?

I'm unfamiliar with countries that have snow in the winter, so I'm unsure whether what I propose is viable, maybe freezing and thawing is no good for bricks and mortar. However, if you are short of cash, can you find enough secondhand/free bricks to make a brick chimney?

Yea I also thought about that, can the chimney be done in normal bricks ? because 1 x fire brick in Denmark is like 10 US dollars, in stores - and not many have these laying around for sale.

But in any case, I'm going to use stainless steel for the entire chimney with no insulation. I'm making the stand big enough, so later on I can build a iron/wood skelleton around to make a "house", in that way i get more insulation in the oven aswell. And I like theese designs more - More materials is normally more expensive though. But this is a few year down the road i guess. The dome will be finished as a igloo to begin with.

Sorry for not knowing all the correct terms

[stonecutter]

Re: Chimney Insulation on WFO?

Yea I also thought about that, can the chimney be done in normal bricks ?

For the veneer, yes...but they are not a good choice for the flue chase, unless there was nothing else available.

[wotavidone]

Re: Chimney Insulation on WFO?

Yep, freeze/thaw = rough on masonry work. There is plenty of masonry done in that climate, but it better be done with best practice through the whole process. Outside of a major event like an earthquake or a truck driving into your work, nothing is more damaging to masonry than freeze/thaw.

If you mean build the flue out of brick, then no, it's not a good idea. Clay flue with a brick surround is the way to go if he doesn't use SS.

Thought that might be the case. I suppose "best practice" means that since you can't control the temperature you'd better make dang sure that water can't get into the pores of the mortar and bricks where it can freeze and spall everything.

[Tscarborough]

Re: Chimney Insulation on WFO?

"Best practice" means adhering to industry standards that apply to the materials, method, and location of the project. As opposed to "code" which is the minimum requirement, generalized and often not applicable to a specific application. Wood fired ovens often fall into the the cracks of code, so best practice should always be used.