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  #11  
Old 06-19-2013, 01:01 AM
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Default Re: How do you size an oven for bread making?

Mikku......going slightly left field of current post responses.
have you ever discovered some of the older posts by CanuckJim.
Sure oven development on here has been moving forward constantly but I found his stuff informative.......don't know much about where he is actually at nowadays because I went "away" from here for
a while.
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  #12  
Old 06-19-2013, 05:25 AM
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Default Re: How do you size an oven for bread making?

Just spent 30 minutes typing in a post and lost it!
I'll try again another day.
Thank you for those taking the time to give their responses, I know each of you have a busy schedule and I appreciate you sharing your time with me.
Thanks again!

I viewed the bakers' oven tonight--still not complete but I thought had some critical flaws.

Has anyone ever seen a commercial WFO oven with firebox at bottom? Where vapors/smoke/etc must meanander upward thru staggered shelves then exit from top? Will that design ever work?

I'll try to make several short posts as not to loose a lot of work over a missed keystroke.
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  #13  
Old 06-19-2013, 05:34 AM
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Default Re: How do you size an oven for bread making?

Are the principles for a dedicated bread oven same as pizza oven?

Insulated floor
Insulated walls
Ratio door opening to dome (barrel) interior height same
No ratio on oven opening--biggest for maximum access
Ratio of oven opening to chimney cross sectional area
Chimney venting to front--outside of firebox; except for instance where a chimney can be physically closed after firing--then OK to be within firebox

I'm thinking of an alternative method of making a barrel oven using castable; maybe another prototype.
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  #14  
Old 06-19-2013, 05:54 AM
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Default Re: How do you size an oven for bread making?

Quote:
Originally Posted by Faith In Virginia View Post
Thanks Mikku,

I just did not want to start something new.

Jay and the others have made some good points so I will add my perspective.

Bread is a totally different beast for the WFO and if your looking at a bakery that adds all kinds of issues.

I think we all have seen that oven with the chimney coming out of the baking chamber and the last one had smoking problems trying to force everything through a 4" vent...so no telling how that other oven was built.

To determine size you need to know the needs of the customer. How many loaves and what kind need to be baked on a single firing. Most bakery bread ovens have a large thermal mass usually 7 to 12 inches thick in the walls and floors. So they do take a while to heat up.

Now here's the rub, unlike pizza the operating temperature of the oven is critical. With pizza you get it hot and keep throwing in more wood to keep cooking temperatures. With bread you have a narrow band of usable temperatures. 575 degrees and your burning bread ...325 degrees and your crust looks like milk. This is why most bakeries plan to put in the higher cooking temperature bread in first and as the temperature drops puts in bread with lower cooking temperature requirements. It's all about oven management.

Now any load of bread puts a real drain on the available heat. 10 loaves at 1.5 pounds has about 1.2 gallons of water that needs to get heated just by the stored energy of the oven. So you can see that 50 loaves is like pouring in a 6 gallon bucket of water in your oven and try to keep your operating temperatures to where they will still cook bread.

Then you need to know how they like to bake. One big load or smaller multiple loads.
my 42" oven does 10 loaves easy that's 9.6 ish of square feet. But the 1.5 square foot per loaf is a good number for long loaves an loaves of different sizes.

With that you and the owner should be able to figure a good size and oven mass. I almost forgot available space to put the actual oven. Think that's a no brainer.

Things to keep in mind when designing a bread oven, lower ceilings are good for keeping more steam available to the bread. Also if they use sheet pans have the oven door large enough to get the pans through...with that also make sure the oven floor can hold the pans in the way the owner wants. nothing sucks as bad as having a sheet pan that won't fit by inches. Also don't build an oven larger then they can mix dough. If they can't fill the oven then the oven should get smaller.

I don't think it makes a real difference between the barrel and round ovens as far as baking but I think the barrel ovens are easier to load...especially a large oven.

Hope that gives you some idea of how to figure out the size and mass.

Faith
Thank you--lets try starting off on a new foot! Hi my name is Gary, I'm glad to make your acquaintance, my nickname is mikku--in Finnish it means "Michael". Let' see if we can solve some problems and have a little fun along the way!
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Old 06-19-2013, 03:50 PM
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Default Re: How do you size an oven for bread making?

Nice to meet you Gary, I like new feet :-)
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  #16  
Old 06-19-2013, 05:13 PM
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Default Re: How do you size an oven for bread making?

Gudday
I have seem an scottish side draft oven in my youth . Sorry I didn't understand the niceties at that time. But I do remember the firebox was at one end the smoke exhausted across the curved roof to a chimney at the other end. I would guess the chimneys entrance hieght would be at 63per cent of the ovens roof height.
Had sliding steel doors in the front which were low and wide and most probably well lower than the level of the chimney entrance.
Hope my memory serves me
Regards dave
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Last edited by cobblerdave; 06-20-2013 at 04:36 AM.
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  #17  
Old 06-20-2013, 07:06 AM
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Default Re: How do you size an oven for bread making?

Quote:
Originally Posted by Bacterium View Post
Mikku......going slightly left field of current post responses.
have you ever discovered some of the older posts by CanuckJim.
Sure oven development on here has been moving forward constantly but I found his stuff informative.......don't know much about where he is actually at nowadays because I went "away" from here for
a while.
A quick search and it seems like he is doing quite well. As resident baker on his own homepage and affilliated with fornobravo in the sales and construction of multiple WFO in Canada.

Looks like participants to this forum have prospered on their own and their exposure has boosted them in other pursuits.

I'll have to study previous posts to pick up information imbedded.
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  #18  
Old 06-20-2013, 07:14 AM
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Default Re: How do you size an oven for bread making?

Report on local bakery:
I met the local baker and saw his hand manufactured oven.

Specifications: (about)
-approximately 4' wide x 6' tall--maybe 4' deep

-lowest section the firebox
-upper sections were shelved with double doors to each section--full width

-internal shelves; sometimes went entirely to back with front not full depth;
other shelves flush with front- not entirely to back

-designed so that heat/smoke/vapors etc. from the lower firebox section had to meander upward and zig-zag through the oven before finally exiting from top.

-lowest section (firebox) had fan assisted intake air--maybe 4" diameter
-chimney or flue--2 ea 4" diameter exhaust vents near highest point of oven

-oven construction---a cage of steel angle; onto which door frames are attached; lowest firebox--next progressing upward (double doors) 4 high

-into this framework- oya stone slabs are inserted---as walls and shelves

-oven doors have a loosely installed fiber gasket to seal door entrance

-absolutely no insulation of any kind on entire oven.
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  #19  
Old 06-20-2013, 07:17 AM
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Default Re: How do you size an oven for bread making?

Bread bakers complaints or report on oven operation:

- oven takes a very long time to heat up--sometimes up to 7 hours with oven temperatures rarely exceeding 300 deg C

-problem with smoke

-interior oven covered in a thick layer of soot
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  #20  
Old 06-20-2013, 07:24 AM
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Default Re: How do you size an oven for bread making?

My observation and recommendation:

-I thought that location of air entrance should be firebox door rather than a different location--making drafting more controllable.

-I thought that chimney size was not adequate--suggested changing to 8" or larger and increasing height of chimney!

-recommended building a steel stud enclosure around the oven; clad with a non combustable material; and then the cavity between the wall and oven--filled with loose fill perlite or vermiculite

-recommended lining oven shelves and wall sides with firebrick

-recommended adding insulation to the oven doors to make them more capible of retaining heat.

--the baker is scheduled to open the new entity--around the end of June or the beginning week of July.

I offerred the use of my oven--only needs to be transported to his house/bakery via boom truck and set down. He paid for transportation only! This is just to acquaint him with a well insulated oven compared to his build!
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