[Stoves] TLUD-Oven!

[James F. Hensel]

Marc,

I watched a TLUD oven work at stove camp on Thursday with the gas exit at
the top of the dome.  I believe this oven was built by the rechoroket folks
although I was a bit confused about that.  It looked very similar to yours.
 In my mind a small dome with a hole at the top with a door almost the same
height as the dome.

My experience is with black hearth ovens, both Kiko Denzer's *Earth Ovens *
http://www.amazon.com/Build-Your-Own-Earth-Oven/dp/096798467X and Alan
Scott's brick ovens http://ovencrafters.net/ as well as a brick oven yahoo
group https://groups.yahoo.com/neo/groups/brick-oven/info

In the case of black ovens like mine, the dome of the oven is appreciably
higher than the door lintel.  In the case of both of my ovens, the door is
about 10" high and the interior dome height is 16".  This ratio of door
height to dome height was also talked about in *The Bread Ovens of Quebec* [out
of print but I have a photocopy here somewhere]. This ratio optimizes the
draw for the fire without excessive cooling in the oven.  I don't think
there is any empirical data on this rather I think it was learned through
trial and error.

A "white oven" is one where the fire box is separate from the oven itself
unlike a black oven where the fire is built on the oven hearth. I think
there are two styles of white ovens. In one style, the flue gases travel in
flues immediately adjacent to the oven but not in the oven itself and in
the second, the flue gases travel through the oven.

Your TLUD oven has the flue gases traveling through the oven. If I were to
apply what I know and see from my black ovens to your white oven, I would
make the oven shape much like a black oven paying more attention to ratio
of the dome height to the door height.  I would not put the flue exit at
the top of the dome.  Rather I would make the flue gases exit the door and
then add a chimney in front of the door - just like my black ovens.

I believe this circuitous route of the flue gases would improve the heating
efficiency of the oven, but that is just an educated guess.

While I am at it, there are other changes I would make to the TLUD Oven.  I
would not connect the TLUD at center of the bottom of the oven.  Rather, I
would attach the TLUD near the doort of the oven and force the flue gases
to travel under the hearth (think of it as a large deflector plate) all the
way to the back wall  of the oven and then have the gases exit upward at
the back of the oven hearth and back out the front door.  You could play
around with the thickness of the hearth as a way to adjust the relative
heat of the hearth. You may want the hearth thicker at the front where the
flue gases first contact the underside of the hearth and then thinner
toward the back as the gases cool a bit.  Alternatively, you may want a
true deflector plate below the hearth so the heat is more diffuse when it
hits the underside of the hearth.  Here is a picture of the general idea.
http://brickovendiaries.wordpress.com/2011/04/01/initial-white-oven-design-for-mobile-truck/
 This is not a TLUD of course, but the rest is similar.

Hope this helps,

Jim Hensel
Portland, Oregon
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