Chimney spec

[wood11]

I want to use bricks for the chimney. I have seen many photos of brick chimneys but am unsure if there is a steel flue inside.
Is it acceptable to use normal house bricks?

[texman]

You can use house brick for your flue veneer as long as you have at least a double wall insulated chimney pipe. Don't use house brick directly in contact with the heat of the fire or its' exhaust anywhere in the oven. most builders use normal brick for the chimneys, when the chimney is exposed. Depends on your oven stye. Which type are you planning?

[UtahBeehiver]

Here are some other schools of thought regarding brick chimneys.

https://community.fornobravo.com/for...lled-stainless

[wood11]

texman, I assume you are inferring: either (1) steel pipe (2) steel pipe + house bricks as veneer (3) refractory bricks, no pipe. Is last option valid?
The type I am building is a 1m wide, and about 0.4m tall, with opening less than 2/3 of the 0.4m. Still in design mode though.

[texman]

Yes, all of your three options are viable. The chimney of firebrick will be the heaviest option. Are you considering an igloo type oven, enclosed(like mine) free standing enclosed, or other? You will need roughly a meter of height for your chimney to draw. But that height becomes widely variable depending on your design. Do you have any sketchs done to post? Pics of other ovens so we can know where you are headed?

[Gulf]

I did an all masonry chimney for my WFO. To reduce girth, weight, and brick, I laid the firebrick liner as shiners. I cut the facebrick back to 2" leaving a 2" void that was filled with vecrete. Here is a Picasa album with a few more pics of it: WFO Chimney.

For my Outdoor Fireplace, I laid very dense clay pavers as stretchers to line the flue above the smoke chamber. The face brick on it are separated by about a 1/2" of space.

[wood11]

texman, thanks for clarifying. Attached is design so far but it will change for the front/chimney. I can tell that there is a lot of thought required.
Gulf, photos help.

[UtahBeehiver]

If you decide to install brick around the chimney, you may have to bolster the side walls of the vent arch due to the weight of the brick.

[wood11]

Understood!

[wood11]

Is it acceptable to have part of the chimney as a mortar mix with steel reinforcement inside, as per attached sketch. Any experiences?

[Gulf]

It is not good to have rebar in refractory due to the different expansion rates when heated. That section (and entire ovens for that matter) have been succesfully cast. Here is a search of the site for cast ovens. I'm sure that a recipe or two for cast refractory can be found somewhere in there. When searching through the threads pay particular attention to any comments by david s . He is an expert on refractory casts.

In your drawing of the chimney (it may just be a shortcoming in the drafting software) the bricks are not laid correctly?

[wood11]

Gulf, insightful.

[wood11]

Gulf, could you please elaborate on post #6.
- What does "firebrick liner as shiners" mean. Is the firebrick the liner? What about the mortar specification, such that it doesn't degrade.

My confusion comes because I only had envisioned a layer of firebrick only. Only just learning that chimneys are apt to fail.

[Gulf]

Maybe this link will help with the definitions of stretcher and shiner. My chimney goes through a wood framed roof. Masonry chimneys are usually 2 layers of some type of masonry. Nowadays, most are built with a clay liner and a surround of face brick. Finding a clay liner that is the perfect size for a WFO is not very easy. Going back to post #6: The first pic and the link "WFO Chimney" shows how I used the firebrick laid as shiners to line my chimney. The 2nd pic and the link "Outdoor Fireplace" will show the firebrick (in my case a very dense solid clay paver) laid as stretchers with a face brick surround. If your oven is sitting out away from any other structures, you may be able to get by with just building the the chimney with just one layer of firebrick laid as stretchers. I don't advise that but, I've seen it done.

EDIT: The most economical and probably the best mortar for a WFO is what we call "home brew". Sand, hydrated lime, portland cement, and fireclay, At 3-1-1-1 parts respectively.

[wood11]

Thank you again.