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-   -   Dome inner height?? (http://www.fornobravo.com/forum/f8/dome-inner-height-12930.html)

WoodchuckDad 05-14-2010 05:42 AM

Dome inner height??
 
In the plans I downloaded the Tuscan style dome had a rounder and higher arch. The illustration used half size bricks on end as soldiers. I see that a lot of folks on here use full size soldiers and build the round dome tuscan style oven, some folks have even made theirs almost a cone shaped beehive shape. I am wondering what that does to heat up times and heat retention and especially to cooking time and performance.

Thanks.

WCD

SCChris 05-14-2010 06:16 AM

Re: Dome inner height??
 
Most around here build a hemisphere, the "indespensable tool" makes this shape pretty straight forward. I don't see any advantage to going conical, but some choose to have a lower interior, tuning the oven for pizza rather than a more general useage. The entry opening is felt to be most efficent at 63% of the interior oven height.

Chris

gdest 05-14-2010 07:45 AM

Re: Dome inner height??
 
I started my oven and made the first shoulder course full brick except for the angle cut at the top of the brick.
By doing this I now realize that my indespensable tool is now about 1/2" short from the face of the brick but it should come back down as my chains progress.
I know I haven't answered your question directly about the heating of the oven. What I have indirectly eluded to was...heck guy who cares! Lets just get this thing built!! LOL
Good luck.

Glosta 07-21-2010 05:26 PM

Re: Dome inner height??
 
I have repeadly seen FB member repeat that the WFO are most efficient at 63% oven door height to interior dome height. What is the basis of this assertion? I can understand that a higher ratio from a higher door will allow more of the heat to escape out the stack and require more wood for heating.
But will a lower ratio-resulting from a higher dome like 24 inches or 28 inches cause poor oven performance?? Why?? The FB Pompei manual states there are many higher interior domes built. What is the downside of a slightly higher dome? Does it affect any type of cooking? Which & how? Is the desire for the low 19 inch interior dome focussed on having a hot 800 degree ceiling only 18 inches away?? I find it hard to believe that a dome height at 24 or 28 inches away will result in any appreciable cooking difference in an 800 degree oven.

Obviously more height means more bricks & mortar; hence more mass to heat up to temperature & more fuel. However assuming the same door height won't it hold its temperature better? One member suggested the fire would burn less efficiently? How was that determined? Has any one performed an air flow study? I would like to hear from a member who has extensive experience cooking with low dome & higher dome ovens? Maybe the Moderator can shed some light. Right now I am paralyzed with indecision at the sixth chain about how aggresively I need to curve the chains in. AHH!!! SHOOT ME!

Tscarborough 07-21-2010 05:37 PM

Re: Dome inner height??
 
My understanding is that the theories have been tested in practical use for 2 or 3 thousand years (and they had it figured out that far back), so the data is empirical rather than modeled. Build a couple thousand ovens and tell us your results (on a computer, I would hope) of the various possible ratios.

dmun 07-21-2010 06:06 PM

Re: Dome inner height??
 
I've been in this forum from a few months after it was established, and the one piece of advice that has remained constant is the .63 door height to dome height ratio. Now, if your dome is a little high in proportion to the dome height will it make a big difference? We just don't know. The data isn't there to make an informed choice.

To review: your entry is built and the door height fixed. You are now building the dome and you're stressing about the difficulty of building the lower dome you have planned. Am I missing anything?

If it were me, I'd angle some bricks for the corner, and press on with what you have planned. Or you can make the hemisphere dome, and re-do the entry. If you make a high dome with a low door, you are in somewhat uncharted territory. My guess? I don't think it would make that much of a difference.

Tscarborough 07-21-2010 06:13 PM

Re: Dome inner height??
 
Exactly, it is all about optimization of the advice presented. Aim for the optimum and accept that you will not always hit it. There is enough slop built into the inherent capabilities of these ovens as designed that they can work well within a broad range of "as built" characteristics.

What you don't want to do is wander off the farm in planning and meander out of state in execution.

Glosta 07-22-2010 09:33 AM

Re: Dome inner height??
 
Thank you for the quick responses. You both have it exactly right. Doesn't seem like the dome is curving quick enough so--I am worried- I don't want to end up with a too tall behive that doesn't cook--So I jumped up outside rise to 3/4 & filling with Heat Stop 50 and fire brick wedges this mornig- I will recheck may use a one inch wedge on next chain--Thank you for the reassurance.

DaveW 07-22-2010 10:08 AM

Re: Dome inner height??
 
Quote:

Originally Posted by Tscarborough (Post 95089)
Exactly, it is all about optimization of the advice presented. Aim for the optimum and accept that you will not always hit it. There is enough slop built into the inherent capabilities of these ovens as designed that they can work well within a broad range of "as built" characteristics.

What you don't want to do is wander off the farm in planning and meander out of state in execution.

Agreed. Ours turned out to be 13/19.5 =.6666666 or precisely two thirds of the oven height. For some reason this seems more poetic then .63. I had planned on 12inches but since I was using an arch I figured I could go a little higher at the apex. I hadn't thought about the trapping of hot gasses. Oh well, add one more to the thousands of slightly deviant ovens that work just fine.


Dave


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