How do you size an oven for bread making?

[mikku]

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!

[mikku]

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!

[silvfox]

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.

[mikku]

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?

[mikku]

Re: How do you size an oven for bread making?

Over the last week, have been doing a lot of thinking about this bread oven.
Now I am thinking about casting one based on the design in the previous link.
I think all of the bases can be covered quite nicely until getting to the oven door. I am assuming some type of loading device would be used to get the bread in and out of the oven quickly--so the door should be something that can open and close quickly and open only to the height required for loading. My thoughts are toward something that would slide up and down, probably cast also--so it would be quite heavy (with insulation and outside shielding). There would have to be some kind of track assembly and counter weights to assist in opening and closing.

Does anyone have any thoughts on oven doors for an oven with possibly a 4 foot wide opening? This would be a smaller version of the previous link but still would be able to produce a lot of bread.

Is there a lot of advantages of having an ash dump to the side of the inside of the oven?

[mikku]

Re: How do you size an oven for bread making?

Thanks for the information on the oven built by sgregory. That guy has a whole lot of talent--it shows in his oven construction and attention to detail. I see that there are other familiar names posting on this thread. I will have to take the time to search other things that are available through that forum. Thanks again!

[vtsteve]

Re: How do you size an oven for bread making?

Check out this thread on The Fresh Loaf: Semi Commercial WFO in Progress | The Fresh Loaf - it's strongly influenced my plans for my next oven...

[mikku]

Re: How do you size an oven for bread making?

There are all kinds of bread in Japan--if you call "store bought" bread or cooked "white paste".

There are a lot of sweat or filled breads you can get at convenience stores.

There are a few very good bakers of sourdough hearth bread like Laurentius, if you talk real nice to him, you might get a taste of his specialty.

I get Rye bread made with molasses regularly from our regular oven--only once from our WFO--and in a very dark version--called CHARBREAD--because it resembles charcoal more than bread...My mistake burnt bread.

A regular treat for kids is Hokkaido milk bread...very light, soft and sweat. so there is some room for bread making here.

[mikku]

Re: How do you size an oven for bread making?

As I said in a previous post, I have never seen a commercial bakery oven--at least a WFO type. There was a bakery near my workshop in Minnesota. His oven was a steel shell fired by natural gas and the rack that held his baking items were on a ferris wheel type of contraption. The racks would be added and on one side--possibly removed on the other--as they moved through the oven.

My oven when I start it smokes a little and soots up the dome every time it is fired. At some temperature--that I have not determined--the soot just disappears, that is every firing cycle. I have small remnants of soot where the smoke and gasses leave the oven and exit by the insulated ss chimney.

The soot that I observed at the bakery, hung off everything in the oven (like cobwebs and dust in a very old building)- I think that he is using a poor quality wood; lack of proper venting so the smoke just hangs in the inside of the oven and whatever contents it holds just cling to the interior cool surfaces- I don't think that the fire is really burning properly. I just have not seen enough ---or there are just too many little factors that are not working.

Possibly if he had LP burners in the same configuration, it would heat better--but even LP soots without the right air to gas ratio.

Costs of fuels in Japan per BTU have Electric being the highest, LP and LNG being second, kerosene third, heavy oil (like fuel oil fourth)--I do not know wood costs to compare...If the wood had to be all purchased, it would be considerable as well!

I think the baker is trying to make a niche business with wood fired bread baking. I'll let you all know what I find out the next time I talk to him.

[cobblerdave]

Re: How do you size an oven for bread making?

Gudday
Soot is not a problem I would think as the smoke and heat pass through the domed roof where its burnt off in that high heat zone. Think of you own domed oven . Light a fire and you get a lingering layer of smoke forms above the floor in a layer till the heat builds up in the dome and it suddenly disappears.
Do you think those shelves would be a contributing factor to the build up of soot? As there is no one surface to get super hot and radiate the heat back to complete full combustion of the smoke?
Regards Dave
Thanks for the insite on bread in Japan , I visited 29 yrs ago and at that time the only bread I can remember was a Macdonalds bun!

[mikku]

Re: How do you size an oven for bread making?

At this point in this bakers' business plan...I think that modifying his present oven--adding firebrick to his shelves; additional brick oven walls; and trying to create a better flow of gasses through his oven when it is firing are minimums that can easily be accomplished.

The additional brick adds some mass--if mass is the biggest issue, it can be easily added to exterior.

I do not know what kind of wood he is using for firing--maybe a straight hardwood would help cut down on soot.

I have never seen the inside of a commercial wood oven in operation--is it soot free?

[mikku]

Re: How do you size an oven for bread making?

Bread making in Japan may have a long history, dating to the times first foreigners were allowed entrance. Bread consumption by the general public has a very short history--a lot to do with the end of WWII, Pacific War and beginning the new Japan we know today. The USA promoted use of wheat to boost our exports to Japan. Now, Japan is trying to modify the appetites of their population by formulating bread based on rice flour.

This bakers' idea of WFO baked breads and bakery items in this tourist area is probably great. If you can make your product "A BRAND"--if you know my meaning. People will buy it by name recognition only and pay a premium as well--at least here.

[cobblerdave]

Re: How do you size an oven for bread making?

Gudday
I did a little hunting up to find out what does make a bread oven differ from the forno ovens we build. I found s confusion of things ...plenty of adds to. The main thing seems to be as Faith said ....mass .
The Formos are a small oven and I think rely on the insulation to make them work well enough for the heat we put in them. The bread ovens are as I remember them massive. The one I found was Red Beard Baker in Victoria Aust.
60 tons of brick and sand held together with steel rods least the Expantion pull it apart. 16 sq mtr of oven hearth under a domed roof which once fired can produce 1000 loaves from a single firing.
I suppose when you think about it heat moves througho a mass at the same speed . A small oven it travels and is lost quite quickly unless hypa insulated. With a big oven like the red beard one the heat would be held in the mass for a longer time just due to the thickness of the thing. The sand rather than insulating as such would allow the heat to escape from the oven face at a slow rate due to the amount rather than the efficiency.
Anyway watching this post with interest
Regards dave
PS you baker friend sounds like is trying to build a traditional oven on modern lines . The multiple decks and shelves are a design of modern gas fired bread ovens. Pherhaps you could point out to him that a more traditional design would work better as the design goes back many centuries . The Japanese respect tradition and bread baking is not I would think a traditional Japanese thing

[mikku]

Re: How do you size an oven for bread making?

My thoughts on the oven:

-better to tear the entire thing out and make a barrel type oven sized for his mixing capacity and sales needs.

-short of that; I felt that he would never get a great functioning oven.

-the baker spent a whole lot of time making this oven...hard to accept advice from a foreigner and squash his dream oven plans!

I told him that I could help him--but in the end; I felt the oven would always need a lot of maintenance and would always consume great quantities of wood!

[mikku]

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!