Texman Build

[texman]

Re: Texman Build

Thanks Gulf for the flue help!
I really need some guidance and advice as to whether i should add a thermal break in the floor on the entryway. The picture attached shows my current situation. Just poor planning on my part. I can cut three of tiles on the wetsaw since they are not attached. But the other two are where the arch sits and will have to be cut with a circular saw and diamond blade, i guess. I think the blade will cut this firebrick. I havent tried it but i can test to be sure. But even at full depth, the saw will leave around 1/4" of the cut since the blade is not big enough to cut full thickness of the floor. i can manage that with the angle grinder i think. But no margin for error on the two under the arch. i dont think they should crack and i am fairly confident of a straight cut. But is all really worth it at this point? How much performance gain do you guys think the thermal breaks are adding to the overall oven performance? I am thinking of the same type as Deejay and aidan using stainless and ceramic rope to separate brick from steel. Seems like the rope is doing the work and the stainless is more for appearance. I like the stainless look, just trying to understand. Also, i am not convinced of the benefit of the heat break at the inner arch to outer arch contact because of all the heat of the gas. Since heat rises and is stored in the dome, doesnt that mean the thermal floor breaks are less effective also?
Thanks for any and all help.
Tracy

[deejayoh]

Re: Texman Build

Tracy -
The value of the heat break between the inner and outer arch is for preventing heat migration out of the dome after the fire is out. Theory is that the oven should be hotter on day two and three with a heat break than without. I don't think there is much benefit to be derived on day one when the gasses are flowing through the flue.

I do thing there is more benefit from the break in the vent than in the floor. I put the break in the floor mostly because I wanted to put soapstone there for appearance and durability/cleanability.

FWIW - after installing the rope and the caulk in the arch, my recommendation is to go with caulk only. The stuff I got dries super hard and is going nowhere. I'd rather have two tubes of caulk than caulk + rope or rope only. I think I may be the first to try that Kaowool caulk - but I am impressed enough that I would recommend others adopt it as the way to go.

[Tscarborough]

Re: Texman Build

A couple of things.

First you should always use the rope, it serves to shape the caulk into an hourglass (when properly tooled), which is the desired shape for a flexible joint. Second it prevents 3-sided adhesion of the caulk which is a common cause of failure in a flexible joint. Even though it gets hard, it is still a flexible joint, since it is softer than the materials around it (or at least it should be).

On thermal breaks, I think they are a good idea in general, so long they do not compromise the integrity of the structure. Done well they should strengthen the oven. Slip joints seem to work best for ovens because of the thermal expansion. Just remember that you do not need a big gap, 1/8"-1/4" is fine for most areas (The joint on my back wall is bigger, but the barrel expands quite a bit).

[GianniFocaccia]

Re: Texman Build

Hey Tom,

If I recall, the gap between your entryway and oven was about 1/4", right? I am planning to build the entryway to my pompeii as a standalone vault that just barely contacts the oven's inside arch with a 1/2" gap on the outside of the adjoining arches. This gap I plan to cap off with ceramic rope. Will I have any challenges keeping these two structures in contact with one another?
John

[Gulf]

Re: Texman Build

Stacy,
It looks like your cut line is about 1" from the face of your inner arch. Most 7and 1/4" saws will need a minimum of 1 and 3/8". I'm not sure what size circular saw or blade that you have. You mentioned the depth of cut for the blade would leave about 1/4". If it were me I would set my cut line out to at least 1 and 1/2" from the face of the inner arch. By doing that any saw that can accommodate a 7 and 1/4" blade can be used to finish the cut. Any cheap 7 and 1/4" masonry blade should be able to get that last 1/4".

[Tscarborough]

Re: Texman Build

@John, no problem at all unless the slab moves which is very unlikely. There is no gap between mine, I thinned the brick down to a 1/4-3/8" at the juncture to minimize heat loss, but it is in contact.

[GianniFocaccia]

Re: Texman Build

Thanks, Tom.

[Amac]

Re: Texman Build

Tracy - I am not sorry I put that small break there - but I am not sure I would have tried cutting bricks in situ to achieve it. I don't know to be honest what the performance improvement is since I haven't used it a lot. I did some measurements on the bricks inside and outside the steel with the IR and promptly mislaid them. Next time I'll post them so someone can do a comparison. As for appearance - after I dropped a brick down the flue there is a nice indentation there now to enhance that.

[texman]

Re: Texman Build

Thanks for all the great answers. You guys give the right answers even when i dont ask the right questions.
The outer arch is in. I have 14 x 5 vent and i am going with 7" triple wall. Went pretty good i think. i used the gauge to make sure the bricks were aligned correctly on the arch. Just a piece of wood the width of the brick cut to a point in the center. It really helps on lining up those arch bricks.

Trying to figure out the vent now. i left a 3/8" gap(break) between inner/outer arch and the floor/entry. I ordered 3/8" ceramic rope and some Kaowool too. Since my flue will transition back towards the dome, I am trying to figure out how to have a thermal break there. Any one have any pics of that?
Tracy

[Gulf]

Re: Texman Build

Sorry Tracy,
I can't help with a pic. My build transitioned in. I think I see what you mean. Your inner arch does not protrude outside of the dome very much. You may want to go up a course higher with your 14 X 5 vent square before starting a transition.

This one (not to scale) shows it starting right on top of the outer arch. Going up vertical one more course or two would give you more room between the dome and the flu for insulation. If I am way off base from what you were asking just excuse my cartoon drawing .

[deejayoh]

Re: Texman Build

Tracy - I don't have a picture of this - but I can tell you what I did.

On the back side of my vent opening, I cut 5 bricks in an upside down "L" shape - they were about 5 inches wide at the top, and only about 2 inches wide at the bottom. I put them in so that the short leg of the "L" overlapped the inner arch of my oven, and the long leg became the back wall of my vent. That way I had a decent amount of surface area to add some strength to my vent arch, and it was wide enough to build the back transition for my vent pipe on top.

Then I stuffed the CF rope into the opening from the back, Kaowool in the front.

[texman]

Re: Texman Build

I got started on the vent and flue. i am "stepping back" over towards the dome to gain the depth i need. I used "saddle" cuts over the inner and outer arch to get flat and level. I used a 40 degree cut between the saddles on the vent sides to make the vent sides go vertical. I will have to do another course or two to get where i want.
pics of my thermal breaks attached as well. Seems strange to have that gap between arches. i plan on using square 3/8" braided insulation tripled/quadrupled, whatever i can get in there and the Kaowool caulk to seal even more. I am thinking about some vermicrete on top of that on the outside.
My actual opening is 6 7/8" after the 1.5 courses. I could round out the bevels in photo D and get the extra i need to 7" +. Or should i go up some more and create more of a funnel?
Tracy

[texman]

Re: Texman Build

Tracy - I am not sorry I put that small break there - but I am not sure I would have tried cutting bricks in situ to achieve it. I don't know to be honest what the performance improvement is since I haven't used it a lot. I did some measurements on the bricks inside and outside the steel with the IR and promptly mislaid them. Next time I'll post them so someone can do a comparison. As for appearance - after I dropped a brick down the flue there is a nice indentation there now to enhance that.

Oh No. Did it hit the stainless or chip your entry? i really like your stainless and planned to do that. I had trouble finding the stainless and was ready to move on. I was looking at mine and found a piece of 1/4 aluminum from an old window screen frame. It slide in so nice and actually looks good. I don't know if i will use it on the floor break or not, but aluminum should be a good material for there i would think.
I measured for my chimney height also. I need a minimum of 5 ft. above the roof to get the 2' above 10' away. I will go with around 6' there and about 2' below the ceiling, so 8' total. That should suck everything out pretty good i hope. I am considering using a ceiling plate to support the weight of the chimney. I think it is a good idea except it complicates the transition from the oven vent to ceiling. It will have to be exact measurement i think?
Tex

[deejayoh]

Re: Texman Build

FWIW, Aluminum is one of the best heat conducting materials out there. Probably better to have firebrick in there than aluminum.

[texman]

Re: Texman Build

i was thinking it was great for high temps, but it seems like all metal is highly conductive. Do you think the Kaowool would be a good finish there instead? If it cures hard and is somewhat flexible, maybe that would work for a small break like mine. i can find some metal probably, but it doesnt seem like a really conductive metal is much better than a low conductive metal. I dont know the physics of the difference between metals conductivity ratings and if it makes a noticeable difference in performance. I wonder if the KAwool is safe for food contact?
Tracy