40" oven build with questions I couldn't find answers to.

[UtahBeehiver]

Karangi Dude did some temperature test on floor bricks via thermocouples, just going by memory, the bottom to the fire brick floor never approached anything close to 1000 F. Do a search under Karangi Dude for this post/info. Since you are enclosing the oven in a cylinder, why not use dry perlite or vermiculite for backfilling the dome, it will have a higher K value than a p or vcrete and weigh substantially less.

Never worked with PyroGel but did look at specs, good K values (standard units). Kind of soft on the compression end but it isn't very thick either. After reading your intro again and the oven being enclosed, the potential of water migration is greatly diminished plus it is inside. I do not think wet insulation will be an issue. Why use both k-26 on the flats over 4" of 5 to 1 pcrete, then you will have a highly insulated floor.

[Ible]

Thank you for the information, well that wont work for a floor insulator, thank you this is where a bit of info goes a long way. , so I will use the k-26 on the outside of the build, and back fill the void with P/V crete and use 4" of PV crete for the floor insulation, have you ever worked with PyroGel, hps, the thermal conductivity for this is .35, , I know I can weld pipe with a bare hand with a thin sheet of this to insulate myself from the arcs heat... and it wont retain water I can lay a layer under the floor bricks but it only does 1200 degrees don't know if that's enough, but I dont think the floor gets to 1000 degrees, I know the dome gets to 800+

also should I wrap the oven with a blanket before back filling the entire dome to allow for expansion of either the PV crete or the fire bricks so I dont get expansion crack/explosions??

[UtahBeehiver]

You can do what ever you want, just making suggestion based on k values of material.

P/V crete 5 to 1 (which is typically used under a floor and more structural) is .72 to .75 in English units which is about 0.12 in Metric units so a IFB of 0.193 is just abt 1.75 time more thermally conductive than 5 to 1 p/v creter. See attached chart.

Here is another manufacturer of K 26 IFB, K value is slightly better than I originally posted but in the same general range.

Several builders have used angle iron for the lintel over the door. You just need to make allowance for the steel to be able to expand and move due to the high expansion ratio relative to the fire brick. It is is set solid into the brick, cracking could occur.

[Ible]

I tried to look up the thermal conductivity of the k-26, but found no data, doubled on the bottom seem a bet excessive, most people use perlite,base which should have a higher thermal conductivity, is that correct? well I knew they were not strong I can pour 2-3" of concrete around the entire cylinder, reusing the forms that I will have to make for the base, Thank you, good to know about the door, does the door have to be arched to make that percentage number or can I use heavy angle iron to hold up the opening bricks and have the opening straight across like a rectangle? either way it will more or less look like the photo when done

[UtahBeehiver]

This will be interesting to follow so be sure to post a lot of pics.

Comments

Door height is correct 63% of dome height 20 x .63 = 12.6, could go up to 65%. Width is builders choice, height is what is critical.
Just to confirm, the k26 are really light weight. AKA IFB, in general they have a K rating (thermal conductivity) of 0.193 w/mk at 550C, comparing to CaSi Thermal Gold 12 is 0.086 wm/k. This mean the IFBs are about 1/2 as thermally effective as CaSi. Since you have quite a number of IFB bricks you might consider a couple layers, one on edge, second on flat giving 7" of insulation or abt 3.5" of CaSi equivalent.
What did the artist use the kiln for? You have to careful of what was fired in the kilns due to residual heavy metals, IE Low fire glazes, usually really bright colors, may have lead in them.
Full depth fire brick on dome will work but it is a ton of thermal mass and will use a lot of fuel to heat up. Unless you are doing production bread making it is really too much mass, stick with half bricks and insulate well.
IFB are very soft and do not have the structural strength alone for the cylinder or use for attaching tile/glass

[Ible]

So first post, The oven is starting to get real, was able to buy hundreds of Diablo fire bricks, (3800 degree fire rating) it’s their third/fourth life, they came out of a sugar refinery and then was used for a huge Kiln for a notable artist. And then was dumped, and buried on the side of a house infested with cockroaches… Yes it was disgusting, there was thousands of them with the bricks. I Sealed my trailer and then bombed them for days. Power washed them, and then ground and or cut the bricks outer layer off, so no more standard size. Now the bricks are in San Francisco, and I’m pre-cutting them for a 40” oven, that will be built in Mazatlán Mexico for a commercial Pizza oven in my art gallery. along with those bricks I have hundreds of k-26 ceramic bricks. I am planning on using for insulation. I searched all the post but couldn’t find anyone using full bricks only half bricks, they way I read it is if I use full bricks I should be able to retain more of the fire’s energy. I am shaping them for a very tight fit with only 1/8 mortar joints.

The oven size is 40” with a 20” dome, 20” wide door with a 12.6” high door 9” vent/Flew
The igloo shaped oven will be surrounded by the Ceramic bricks and then back filled with perlite cement mixture, The finished shape will be a tall 6’ Diameter cylinder by 8’ tall the entire unit will be covered in broken sea glass and polished, (done this work before it’s a pain)

ok now questions
Has anyone used full bricks, couldn’t find any post on the subject.
will one layer of k-26 ceramic bricks be enough for the floor insulation? Or do I have to place them on their side for a 4.5” insulation?
Does anyone know the R Rating of k-26 bricks per inch”
Is the opening too wide at 20”
Is my math right or can the opening be taller?
Can I thin set glass tile to ceramic bricks or do I need a stucco the exterior also
This will be set on the 5^th floor of my building, it’s a heavy concreate constructed building that was reinforced with 12” i beams, it was the old ballet school and was used as a bomb shelter, so I don’t foresee the weight being a issue. At the moment the 5^th floor is open, but sometime in the future I will be add another floor and this will seal off the floor with the oven, so Im hoping to be able to vent it to the outside wall.