Author Topic: My new oven  (Read 7404 times)

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buceriasdon

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Re: My new oven
« Reply #20 on: December 31, 2010, 02:18:11 PM »
Not meaning to hijack the tread, but seems we have in any case. So this is where a curved roof, whether a barrel type or domed has an advantage over a flat roof? They both have the ability to reflect heat better than a flat roof? So for the same amount of wood consumed they would be more efficient.
Happy New Year, Feliz Ano Neuvo
Don


Looks to have the same issue as most alternative type ovens...no top heat.  Looks like a bigger fire with open flame could help fix that but it seems like the person who built and is using the oven would know that and demo it properly.


Offline cranky

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Re: My new oven
« Reply #21 on: December 31, 2010, 03:46:13 PM »
Not meaning to hijack the tread, but seems we have in any case. So this is where a curved roof, whether a barrel type or domed has an advantage over a flat roof? They both have the ability to reflect heat better than a flat roof? So for the same amount of wood consumed they would be more efficient.
Happy New Year, Feliz Ano Neuvo
Don

Anyone interested in energy efficiency would not have a wood fired oven.  There are two factors to think about that impact efficiency.   Combustion efficiency is one.  The other is how much of the heat generated goes into the food being cooked, the pot, or in this case the pizza.  Traditional wood fired ovens are not that combustion efficient.  One way to look at combustion efficiency is to look at smoke.  The more unburned carbon that goes into the air the less efficient the combustion.  A WFO combusts wood inefficiently and the cooking takes place when most of the heat is coming from coals.  The vast majority of the heat generated does not go into the food, but into the heat sink, the brick.  It takes hours to preheat the oven.  Pretty much all of that heat is wasted.   The pie is baked in two minutes.  If anyone is interested in looking at a wood fired combustion device that is efficient, do a search on "rocket stove".  Dr. Larry Winiarski is the creator of the technology.

buceriasdon

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Re: My new oven
« Reply #22 on: December 31, 2010, 06:37:04 PM »
Ha Ha, Cranky, way cool! Thanks for the info, I did a google search, very interesting. Even some plans out there on the net that could be converted to a pizza oven. If only the inventor had an Italian name........just kidding. Fascinating read. Thanks.
Don
http://www.rocketstove.org/images/stories/rocket%20baking%20oven%20manual%20november%202008.pdf
« Last Edit: December 31, 2010, 06:43:26 PM by buceriasdon »

Offline cranky

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Re: My new oven
« Reply #23 on: December 31, 2010, 07:22:28 PM »
Ha Ha, Cranky, way cool! Thanks for the info, I did a google search, very interesting. Even some plans out there on the net that could be converted to a pizza oven. If only the inventor had an Italian name........just kidding. Fascinating read. Thanks.
Don
http://www.rocketstove.org/images/stories/rocket%20baking%20oven%20manual%20november%202008.pdf


Don,

Larry Winiarski has built rocket stove heated ovens.  I did not see one, but by the description it sounded very interesting.  He relies on insulation to hold heat in the oven chamber, rather than brick (heat sink), to build up heat.  If you have to heat up a lot of dense mass, that is where your heat is going.  The idea is to drive all the heat from combustion into the oven chamber and cook something rather than heat up a ton of thermal mass.  The reason it takes so long to preheat a wfo is you are charging the thermal mass.  Buring a fire for hours to cook a couple of pizzas or some bread is a waste of fuel.  He also built a very large commercial coffee roaster in Central America using the same combustion principles.   He makes his own fire brick.  Very smart guy.  His mission is not to make great pizza.  He wants to help people in developing countries better their lives.

buceriasdon

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Re: My new oven
« Reply #24 on: December 31, 2010, 07:40:24 PM »
Yes, The work in Uganda I found particularly interesting. However, getting back to the topic, :-D wouldn't a dome roof be more effecient than a flat roof? Larry is not interested in making pizza! :o He's not interested in spreading the gospel of pizza worldwide?
Once again..just kidding
Don


Don,

Larry Winiarski has built rocket stove heated ovens.  I did not see one, but by the description it sounded very interesting.  He relies on insulation to hold heat in the oven chamber, rather than brick (heat sink), to build up heat.  If you have to heat up a lot of dense mass, that is where your heat is going.  The idea is to drive all the heat from combustion into the oven chamber and cook something rather than heat up a ton of thermal mass.  The reason it takes so long to preheat a wfo is you are charging the thermal mass.  Buring a fire for hours to cook a couple of pizzas or some bread is a waste of fuel.  He also built a very large commercial coffee roaster in Central America using the same combustion principles.   He makes his own fire brick.  Very smart guy.  His mission is not to make great pizza.  He wants to help people in developing countries better their lives.
« Last Edit: December 31, 2010, 07:46:44 PM by buceriasdon »

Offline cranky

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Re: My new oven
« Reply #25 on: December 31, 2010, 07:56:13 PM »
Yes, The work in Uganda I found particularly interesting. However, getting back to the topic, :-D wouldn't a dome roof be more effecient than a flat roof? Larry is not interested in making pizza! :o He's not interested in spreading the gospel of pizza worldwide?
Once again..just kidding
Don



It probably does not matter that much.  The vast majority of heat goes into the oven walls and roof, not the pie.  My guess is over 99% heats the heatsink and less than 1% the pizza.  If you had oven a/ with a flat roof at 800 degrees and oven b/ with a domed roof at 800, the bake time might be a couple of seconds difference or nothing at all.  How long it would take to charge the thermal mass with the same btu input, would also not be any different.   Combustion efficiency might be improved some with a flat roof with corners, because it would allow the unburnt gases to swirl around in the combustion chamber a little bit and get burned up.   Domed roofs were built to enable the bricks to not fall in.  The arch is self supporting.  Efficiency was not a consideration.

Offline shuboyje

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Re: My new oven
« Reply #26 on: January 01, 2011, 01:40:39 PM »
Not meaning to hijack the tread, but seems we have in any case. So this is where a curved roof, whether a barrel type or domed has an advantage over a flat roof? They both have the ability to reflect heat better than a flat roof? So for the same amount of wood consumed they would be more efficient.
Happy New Year, Feliz Ano Neuvo
Don
Nope, I don't think the flat roof has an effect on the top heat.  Given a evenly heated dome and direct radiation a flat dome would actually lead to the most even heat distribution.  That said the radiation in a pizza oven is diffused radiation, like sunlight on a cloudy day, and in my opinion the shape of the dome has much less effect on that then the distance between the dome and the deck. 

I'm not sure if there is thermal mass on top of the steel of not, but if not the lack of thermal mass could be partially to blame.  The biggest issue I see is the lack of open flame across the dome.  This could be poor fire management by the user, but it could also be due to the ovens design which is not ideal for good airflow.  Sharp corners lead to turbulence which can drastically effect airflow, and from what I see this oven lacks a vent and flue to help create more draught.  I'm still gonna guess it is poor fire management...even lacking air you should get some flame.

Anyone interested in energy efficiency would not have a wood fired oven.  There are two factors to think about that impact efficiency.   Combustion efficiency is one.  The other is how much of the heat generated goes into the food being cooked, the pot, or in this case the pizza.  Traditional wood fired ovens are not that combustion efficient.  One way to look at combustion efficiency is to look at smoke.  The more unburned carbon that goes into the air the less efficient the combustion.  A WFO combusts wood inefficiently and the cooking takes place when most of the heat is coming from coals.  The vast majority of the heat generated does not go into the food, but into the heat sink, the brick.  It takes hours to preheat the oven.  Pretty much all of that heat is wasted.   The pie is baked in two minutes.  If anyone is interested in looking at a wood fired combustion device that is efficient, do a search on "rocket stove".  Dr. Larry Winiarski is the creator of the technology.
I'm not sure what your experience with WFO's is but my experience, and the normal expected experience from everything I read, is that a WFO will create virtually no smoke within a short time of startup.  Now I'm not saying it is a pillar of efficiency, but that also depends on variables.  Firing a 42" brick oven to cook one pie is far from efficient.  Firing one to cook 100 pies is a different story, and firing it for 100 pies every single day gets even more efficient since the oven will retain a huge amount of heat overnight and you will only need to bring it back up to operating temperature each day.

 
-Jeff

Offline cranky

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Re: My new oven
« Reply #27 on: January 01, 2011, 05:47:22 PM »
I'm not sure what your experience with WFO's is but my experience, and the normal expected experience from everything I read, is that a WFO will create virtually no smoke within a short time of startup.  Now I'm not saying it is a pillar of efficiency, but that also depends on variables.  Firing a 42" brick oven to cook one pie is far from efficient.  Firing one to cook 100 pies is a different story, and firing it for 100 pies every single day gets even more efficient since the oven will retain a huge amount of heat overnight and you will only need to bring it back up to operating temperature each day.


Once coals are created in any fire chamber there is little smoke.  There are still uncombusted gases that escape and when new fuel is added is when the uncombusted gases are increased as well as smoke.  Sometimes there is particulate (smoke) and sometimes simply uncombusted gases, generally carbon monoxide which is oderless and invisible.  The design of the fire chamber and how fuel is fed determines how efficient the burn is.  A WFO does not provide efficient combustion.  It is more efficient to heat the oven and bake as many items as possible than to bake a few pies or loaves.  Even then, the majority of the heat still goes into the heat sink, up the stack and out the door as opposed to going into the food being cooked.     

Offline shuboyje

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Re: My new oven
« Reply #28 on: January 01, 2011, 06:31:41 PM »
Like I said before, I agree it is not a pillar of efficiency, but I do not think it is as inefficient as you imply.  Now does that matter?  Not to me, most of us who have wood fired ovens aren't doing it for economy or the environment, we do it because they cook incredible pizzas in a way that is very difficult to replicate without one. 

A lot of what you reference as wasted heat is debatable IMHO.  For instance energy used to heat the thermal mass is not wasted if you use the residual heat stored in that mass.  Thats obviously not as efficient as directly using the energy in the first place but it is also not a total lose.  Energy used to heat the vent and flue is also not a total waste.  It leads to increased draught which yields more efficient combustion and higher temperatures.  Even Rocket stoves are bested by gasifying stoves which use electricity to run a fan to serve a similar function. 

The biggest inefficiency of WFO's is a necessary evil, the gaping hole needed to put in and remove a pizza.  It allows untempered outside air directly into the blazing oven chamber.  Problem is when you are operating at temperatures of 800-1000F and cooking pizzas in as little as 30 seconds that need rotating, a door as would be needed for a more efficient air path isn't really a possibility.
-Jeff

Offline cranky

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Re: My new oven
« Reply #29 on: January 01, 2011, 09:50:14 PM »
Like I said before, I agree it is not a pillar of efficiency, but I do not think it is as inefficient as you imply.  Now does that matter?  Not to me, most of us who have wood fired ovens aren't doing it for economy or the environment, we do it because they cook incredible pizzas in a way that is very difficult to replicate without one. 


Right!  That is the reason for a WFO.  Lots of heat.

Quote
A lot of what you reference as wasted heat is debatable IMHO.  For instance energy used to heat the thermal mass is not wasted if you use the residual heat stored in that mass.  Thats obviously not as efficient as directly using the energy in the first place but it is also not a total lose. 


My guess is that professional bakers who used these ovens for centuries tried to get the most usage out of the heat. 

Quote
Energy used to heat the vent and flue is also not a total waste.  It leads to increased draught which yields more efficient combustion and higher temperatures.  Even Rocket stoves are bested by gasifying stoves which use electricity to run a fan to serve a similar function. 


Gasifiers are more efficient, but very difficult to operate properly.  They are very delicate and need constant attention.  The heat that goes out the flue is all wasted.  It does not heat anything.  If it were directed around the oven chamber some would be captured.  If it were run through a heat exchanger some would be captured. 

Quote
The biggest inefficiency of WFO's is a necessary evil, the gaping hole needed to put in and remove a pizza.  It allows untempered outside air directly into the blazing oven chamber.  Problem is when you are operating at temperatures of 800-1000F and cooking pizzas in as little as 30 seconds that need rotating, a door as would be needed for a more efficient air path isn't really a possibility.

Yes, the door is a source of fugitive energy escape.  The way to make pizza ovens more efficient is to eliminate the heat sink that needs to be charged over long periods before you are ready to bake.  You need heat to bake, but the heat sink also keeps the chamber hot when the oven is repeatedly opened.  So I don't think it is possible to make an energy efficient pizza oven.


Offline sacwoodpusher

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Re: My new oven
« Reply #30 on: January 17, 2011, 01:39:54 PM »
Before I made my last batch of pizza, I visited Mazullo in Sacramento, at about 1:00 PM on a Monday. Nobody else was there, and I had time to talk to the Pizziola. I ordered a pizza, and watched it being made. We had a talk about oven management.

I took my "square" oven, fired it, and brought the oven floor to about 800 degrees. Then, I threw small pieces of wood in from time to time maintaining a fire to the dome and at least 1/3 of the way across the top. I was able to maintain a floor temp of between 725 - 775 degrees, and I noticed that the cheese cooked and the top of the pizza crust browned without doming. So....even if the oven is "no good"......with a little practice and some help with technique, I am able to cook a good pizza in the oven. We cooked a total of 10 pizzas, 10 oz balls....

I made a loaf of Ciabatta last night....and again, it looks like it's gonna eat real good.

Offline Jet_deck

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Re: My new oven
« Reply #31 on: January 17, 2011, 05:38:09 PM »
I took my "square" oven, fired it, and brought the oven floor to about 800 degrees.

With or without propane assist?
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Offline Spydmaster

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Re: My new oven
« Reply #32 on: March 15, 2011, 08:24:41 AM »
Hi I think the better Ovens are the Mediterranian models, on the market are many sizes and shapes Io prefer the Italian Styles.

Best regards with Pizza!!!


 

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