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Old 06-28-2013, 05:20 AM
Master Builder
Join Date: Jan 2013
Location: Japan
Posts: 615
Default Re: How do you size an oven for bread making?

More thoughts on oven design-
When I talk to people about radiant floor heating (in Japan called Yuka Donbol) or floor heating, I try to explain the different ways that heat is transferred.

1) by conduction- if I explain this correctly, it is the transfer of heat from one object to the other by direct contact. You have a warm floor--you walk on the floor, your body is warmed by direct contact.

2) by convection- a warm object heats the air and you are warmed by the heated air. But air is a poor conductor of heat--so it takes higher temperature air to warm something.

3) by radiation or radiant heating-- example--the sun is a super hot object; it sends "waves of energy" that heat anything that is in the direct line of sight of the sun. If you are sitting outside on a sunny day at a table--with your arms and upper body above the table---your upper body will be warmed by the sun, but your legs "under the table" will not! Same holds true for sitting by a wood stove. The heat that the stove produces, radiates heat outward in all directions from the firebox. If you are in a direct line of sight from the firebox, you will feel the heat, if there is a wall in between you and the stove, even half high like wainscot height--the area behind the wall will not feel the affects of radiant heating, only the area above will.

Another important aspect--the closer to the radiant heat source, the greater the radiant factor.

So in a round about way, I have determined why the baker's oven is not working properly.

Since the firebox is detached from the actual oven--all affects of radiant heat are lost.

The interior of the oven is only heated by convective heat--heated air heating the oven or heated smoke heating the oven.

The conductive heat--if fire is in actual oven space; coals in direct contact with oven floor... this is not utilized in the oven design of the local bakery.

The radiant heat--flames, fire, coals, only heat the firebox radiantly. The heated air and smoke are the only things that heat the oven and because of poor combustion, the interior never reaches temperatures necessary to burn off the hydrocarbons in the smoke. The oven acts like a smoke "precipitator" or smoke "still"--the unburnt carbons just attach themselves to the cool surfaces of the oven. If continuously fired , at some point the soot would burn away--theoretically, but that temperature is never met.

I'd like some feedback on this assumption... What is your take on this concept?
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Old 06-28-2013, 08:20 PM
Join Date: Oct 2012
Location: Minnesota
Posts: 43
Default Re: How do you size an oven for bread making?

Mikku, I like your explanation and agree that a WFO fired in the baking chamber utilize all three means of heat transfer while the fire is burning. Once the fire is out and the door closed convection would be nill. Heat is always going to cold so heat is absorbed and stored by the firebrick during firing and heat is reradiated and transferred conductively by direct contact with food while cooking. As the wood stove proves you warm faster when you're in direct line of sight with the source when compared to forced air heat. Insulation is designed to be a poor conductor and or a reflective barrier. If the space shuttle did'nt have reflective tiles it would burn up on reentry to the amospher from the heat generated by friction with air.
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Old 06-29-2013, 04:41 AM
Master Builder
Join Date: Jan 2013
Location: Japan
Posts: 615
Default Re: How do you size an oven for bread making?

Now, I don't know what to say to the new baker about his oven.
I feel confident that his oven will not work efficiently the way it is designed.
I'd like to make him an oven based on sgregory oven on another forum, but made from cast refractory cement entirely. But there is no way to convince him to give up on his own ways.

Language barriers are a huge problem --I have difficulty being tactful in English. That is apparent by the many times I've interacted with members of this forum badly and later come to regret it! Trying to be polite and respectful to his feelings in Japanese is (muri) in English means (impossible).

So, I have to just sit on the sidelines and see the guy go through all these difficulties unable to advise otherwise?

I guess the next best thing is build another WFO for my own use. If it works like I anticipate it will, maybe I'll start making bread as a sideline! Could not find a better way to pass the time as a person ages!

Like the Godfather figure played by Marlin Brando--having a heart attack and dying playing with his grandson in a garden full of tomato plants; me kicking the bucket tipping face first into a batch of sourbread dough---could not think of a nicer way to pass!

I have relatives in the Twin Cities who have operated a family baking business for the last 80 years. Maybe I can tap into some of those resources to begin a micro bakery in Japan!

Sounds like fun to me! Another uncle of mine was a test baker for General Mills. He would use the new product recipes and prepare baked goods for the staff of GM headquarters. The feedback would be used to determine if a new product would be marketed! He has been gone now for many years, but the memory of him lives on!

Chet always had a happy demeanor and was great telling stories at hunting camp. Those days have been gone for a long time but the memory is very clear.

Really love the smell of fresh bread baking!
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Old 06-29-2013, 05:01 AM
Master Builder
Join Date: Jan 2013
Location: Japan
Posts: 615
Default Re: How do you size an oven for bread making?

On a different note, ran into an old friend of mine today...One of the first people I worked with when I first came to Japan 20 years ago. He may be my best source for firewood to date. A friend of his is a "way-key-yah-san" phonetically meaning a person who takes care of pruning and caring for peoples' plants and trees.

Because this guy is trimming and removing trees from peoples properties on a daily basis, he always has mountains of wood--branches, trunks etc--way more than he can ever use. Mr. Murakami said that I can get all the firewood I want forever simply for the cost of transporting it to my property! What a great chance meeting this was!

I also found out that Mr. Murakami has a hobby of raising a few chickens for his egg needs. Right now, he has 5 roosters and only two hens --and he is letting the hens sit on the eggs to produce some new offspring. These chickens produce an egg with a light brown colored shell and the yoke is really bright orange! He said if I wanted to, he would give me a rooster and help me find a few hens. He said a good ratio would be 3 hens per rooster.

Have to prepare a pen and find a good location...He said that the neighbors might complain about early morning crowing, but I said that the poodle breeder in the neighborhood makes plenty of noise when they feed their pups... Just something more to get the pups "yapping"! I have a good source for reject rice used to feed chickens. A friend is a large rice farmer! So looks like a couple chickens for these "Green Acres"! in the near future!
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