Texman Build

[Laku]

Re: Texman Build

Thermal conductivity for common materials

[Les]

Re: Texman Build

Can you get kicked off this forum for making too many mistakes?

If that were the case, no one would be on this forum

[texman]

Re: Texman Build

Just remember....
[ATTACH]30439[/ATTACH]

diamond blades are an oven builders best friend.
i am going to take all my hammers and put them away so i dont have any temptation.

[deejayoh]

Re: Texman Build

Just remember....

[texman]

Re: Texman Build

Here is the plan:
Remove 1.25" from the outer arch vent brick to bring the outer edge to 2.75" thickness. Add 2.75" arch to rear of outer arch and tie arch together.
This will leave a 3.5" x 14" vent. That is 49 sq inches. my 7" flue is 38.50 sq inches. Transition that 3.5" x 14" to a 7" round flue somehow. Hopefully not break the arch and get to start over on that too. Buy some diamond stocks. I am gonna burn some tonight.
What a trip.
Tracy

Can you get kicked off this forum for making too many mistakes?

[deejayoh]

Re: Texman Build

Seems to me that you're fine. especially with that flue height!

Check page 21 of the instructions for your chimney: http://www.duravent.com/docs/product/L150_May2012_W.pdf

there is a sliding scale between chimney size and height. Taller chimney offsets quite a bit of the need for for a larger flue

[texman]

Re: Texman Build


After getting some really good advice; i think that leaving my arch open at the back will put a lot of stress on the front of the arch. I was thinking i could add a connection at the back and add strength. But, What is the minumum vent size for a 7" flue?

Area of 7" flue = 38.48 sq in. If i take my flue to 14" x 3" ( add a 2" arch at back) is that ok? Is there a definitive answer on the vent size/oven size/flue size? I see flue size of 3-4 times door height in the FB plans.

My oven is 37" with a door height of 11.125" and width of 18" and dome height of 20" So 3 x door height is 33 and 4 is 44, my 7" flue is 38.48 sq in so good to go right?

If i go with a vent opening of 14 x 3 (42 sq in.) 42" is greater that 38 sq in of 7" flue, so good to go right?
My chimney will be 7 -8 feet tall if that helps in this discussion.

[deejayoh]

Re: Texman Build

I put the tube in for a few reasons
1) My entry floor is 1 1/4 inches of soapstone on top of IFB splits - so I wanted something between the materials for appearance sake
2) It's a tougher edge at the front of the oven, protecting the bricks from chipping
3) The air gap that the tube theoretically offers an insulation improvement. The conductivity stats on that link are for solid pieces of metal - but the tube is mostly air with only about a mm of solid material to conduct heat.

[Laku]

Re: Texman Build

Depends on how thick the steel is. But same thickens (and size) steel bar is a lot better heat conductor than equivalent volume of brick.

[texman]

Re: Texman Build

thanks, that explains it. But, brick is better than stainless as far as conductivity. Is the stainless more of an appearance decision then?
Tracy

[deejayoh]

Re: Texman Build

The Material Safety sheet on the Kaowool suggested i wouldn't want my food touching it.

I think you'd want a low conducting metal - that is why I went with a piece of stainless tube. It's not a terribly good heat conductor.

There's good data on heat conductivity here that others pointed me to when I was thinking this through
Thermal Conductivity of some common Materials and Gases

[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

[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

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

[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