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scott123

• Guest
Re: Comments on this design for LBE
« Reply #60 on: August 26, 2012, 09:54:28 AM »
We will need a good mass and insulation in the ceiling to catch and radiate the heat downward.

Actually, we don't need that much mass   I don't know anyone with a drago, so I can't say for certain how long it takes to heat a cold, fresh from the factory (or long vacation) oven, but Jeff has pointed out that it most likely takes a very long time, which I'm not disagreeing with.  A contributing factor to that time is the thermal mass in the dome.  As you scale it down, drop the thermal mass, lower the ceiling and go with a much higher BTU to mass ratio, the time shrinks considerably.

I'm not completely ruling out insulation here, but, as I told Bob yesterday, this is basically LBE thermodynamics.  In your average LBE, with the lid on, the proper size vent and a typically high BTU burner, the air foil/director stays plenty hot, regardless of the lack of insulation above it.

Now, I'm not necessarily backing the metal plate ceiling idea.  That could require insulation. I'm thinking some mass- 3/4" or thicker cordierite will, with enough BTUs glow cherry red and shower the hearth with all of it's radiative goodness.
« Last Edit: August 26, 2012, 10:18:16 AM by scott123 »

shuboyje

• Registered User
• Posts: 1312
• Location: Detroit
Re: Comments on this design for LBE
« Reply #61 on: August 26, 2012, 10:32:35 AM »
Scott,

When you use a frying pan in the kitchen do you put it on the burner and heat it up, or do you put a piece of steel on the burner, heat it to red hot and then hold it over the frying pan to heat it via radiation?  Get my point, lol.

If some part of this system was already built, or being repurposed in some way I could see trying to make it work.  Considering the poster is looking to build a custom burner in a oven that does not exist I don't see any reason to take such a round about approach when he can just blast the hearth with heat directly and be done with it.
-Jeff

buceriasdon

• Guest
Re: Comments on this design for LBE
« Reply #62 on: August 26, 2012, 10:59:24 AM »
Just throwing this out for the sake of conversation. Mount a 4" high pressure burner at the rear so it projects say an inch or so into the upper chamber. A slot cut in the lower kettle for the burner tube to set in and a mounted L bracket and hose clamp to hold it in position. Yes you lose that area but you still have fourteen inches of bake area. You must have a large enough vent in the top kettle because the air mixture at the venturi alone is not adequate to keep the flame going, the burner requires surrounding air also.
Don

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