42" or 32" oven?

[pkolonay]

I am trying to get some momentum going with my pizza oven project but can't even seem to get started. I am stuck at the foundation dimensions... the beginning.

The only space where I can do my build will be fairly tight for a 42" oven but it is doable.
While working through location details though, I started to wonder about whether I should go with a 36" oven instead. I hate to give up the cooking space but I wonder how much it matters.

Size is one thing but I am also thinking that a 36" oven would be more efficient (all things being equal) than a 42" oven. My assumption is that a 36" oven would require less wood to get to the same temperature as a 42" oven. Is this a wrong assumption?

My question to those builders that have 42" (and up) ovens is: Are you satisfied with this size or do you wish you had a smaller oven that would not use as much wood and take as long to heat up.

On the flip side, are there builders of smaller ovens that feel limited by the size in some way?

A few folks commented on the subject in the 'What would you do different' thread but I wanted to ask this question specifically to see if more folks might respond.

Thanks for any feedback... my hope is that it will help me get off square one.

Paul

[Les]

Re: 42" or 32" oven?

I am trying to get some momentum going with my pizza oven project but can't even seem to get started. I am stuck at the foundation dimensions... the beginning.

The only space where I can do my build will be fairly tight for a 42" oven but it is doable.
While working through location details though, I started to wonder about whether I should go with a 36" oven instead. I hate to give up the cooking space but I wonder how much it matters.

Size is one thing but I am also thinking that a 36" oven would be more efficient (all things being equal) than a 42" oven. My assumption is that a 36" oven would require less wood to get to the same temperature as a 42" oven. Is this a wrong assumption?

My question to those builders that have 42" (and up) ovens is: Are you satisfied with this size or do you wish you had a smaller oven that would not use as much wood and take as long to heat up.

On the flip side, are there builders of smaller ovens that feel limited by the size in some way?

A few folks commented on the subject in the 'What would you do different' thread but I wanted to ask this question specifically to see if more folks might respond.

Thanks for any feedback... my hope is that it will help me get off square one.

Paul

Paul, I built a 42 and feel that it is perfect. I have had fire on the sides and back with three pizza's in there. I don't think you would ever need more than that - it becomes a chore working the peel. In regard to the fuel - I don't think that there is a whole lot of difference between oven sizes. What does 1 or 2 more pieces of wood mean at the end of the day...

[david s]

Re: 42" or 32" oven?

Disregarding heat loss, the fuel consumption of an oven should be directly related to the mass of the inner dome walls plus the floor. The oven chamber, the engine required to pump in the heat is the volume of the chamber. Because of the mathematics where area goes up squared and volume goes up cubed a small increase in diameter means a massive increase in volume.
I cooked 64 pizzas in my 21" mobile oven last night in two and a half hours alternating the fire on the side three times. I don't know how much fuel i used, but on a previous occasion I weighed the amount of fuel used to get to 350 C in one and a quarter hours, it was a mere 4 Kgs. Obviously I used more to keep the fire going on the side, and I gave it two hours of fire before cooking last night, but a small oven uses way less fuel and if you only cook one at a time then a small oven may be your answer.

[pkolonay]

Re: 42" or 32" oven?

Thanks guys for responding... this forum always impresses me with veteran builders (like youse guys) that continue to contribute and help those legions of the unbuilt.

Les - I have seen a post of yours documenting temps/times mainly focused on heat retention. That's one aspect of efficiency but the other that I was interested in was related to how long it takes the oven to get up to temperature. One post I read on ohthetrees build says that it takes his about an hour to get to 800/900 degrees.(http://www.fornobravo.com/forum/8/co...-14882-2.html#)

david s - You are giving me an idea about the other extreme. It would be interesting to see more numbers like those you provided (temp versus time versus fuel qty) for other size ovens. I have done a 'temporary' oven and found that I can really only cook one pizza at a time when it is at temp.

wotavidone - My usual thinking has me going for the biggest solution (oven in this case)... as you are suggesting. I am just not sure if I would use the addtional size. I have seen lots of great stuff coming out of the ovens on the forum. Pizza is my initial motivation but bread and other slow cooked meals are on the horizon.


I just need to pick one and get on with it!

thanks again

Paul

[Les]

Re: 42" or 32" oven?

Les - I have seen a post of yours documenting temps/times mainly focused on heat retention. That's one aspect of efficiency but the other that I was interested in was related to how long it takes the oven to get up to temperature. One post I read on ohthetrees build says that it takes his about an hour to get to 800/900 degrees.(http://www.fornobravo.com/forum/8/co...-14882-2.html#)

Paul,

I usually take around 2.5 hours to burn completely clear. But to be honest, I never have a raging fire to get up to temp. I typically put one piece in at a time.

[david s]

Re: 42" or 32" oven?

The time it takes to get to temperature is related to how thick the walls and the floor are, so most ovens, big or small, take around one and a half hours. For pizza I like to give mine two hours, but if I'm doing a roast or a few loaves of bread, one hour of flame is sufficient. The heat has not had enough time to penetrate the walls properly, but it works ok in my oven and saves time and fuel. Firing a WFO from ambient to 400C in about an hour and a half is actually way too fast for any refractory material. A slow gentle rise is more preferable. Using a blast door at low temps (under 500C) is likely to be damaging to the refractory, in fact at around that temperature there are physical and chemical changes taking place that require very slow increase in temp, something that is extremely difficult when using wood as a fuel.

[pkolonay]

Re: 42" or 32" oven?

Thanks again for the responses... it sounds to me like 'time to cooking temperature' should not be one of the factors we use to make a decision regarding oven size.

Just relax and enjoy the burn... the pizzas will certainly cook fast enough once the temperature has been reached.

Paul

[aiannar974]

Re: 42" or 32" oven?

David S. -

Do you have any picks or a trhead where you have pics of your 21" oven and you cooking in it? Above you mentions you moved the fire from side to side during you 60 pizza cook, why did you have to do this? I would think (I don't have an oven yet) that the smaller the oven the tougher it is to manage uniform heat and easier to burn one side of the pizza, do you need to spin the pizza a lot? How does this compare to other ovens you cooked in?

Anthony

[david s]

Re: 42" or 32" oven?

Sorry I don't have any pics of actual cooking in my oven, I'm usually too busy when cooking to think about taking photos. Moving the fire from side to side is something most oven owners do because the floor cools off when you continually place the pizza in the same place. I usually remove half the coals before cooking pizza so there is more room. I keep a fire burning on the side over the remaining coals. Regarding turning the pizza, yes I turn the pizza 180 degrees after one minute, but I think this is normal for all ovens. I usually cook approx. 9" diam. pizzas and I like this size because they are easier to handle. Get the pizza too close to the fire in any oven and you will burn the edges.

[david s]

Re: 42" or 32" oven?

Anthony,
I found one. Notice the short handled peel. Coupled with the very shallow entry and the wide oven mouth the peel is used one handed and makes working the oven really easy. We also often use the oven as a fireplace just for comfort.
Dave

[aiannar974]

Re: 42" or 32" oven?

David - Thank you for the information and taking the time to dig through photos. It makes sense. I am not sure I would have though about taking some coals out. Noce looking oven.

Anthony