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james 06-07-2006 12:40 PM

Oven opening size
 
You are working to balance two conflicting requirements with your oven opening.

First, the smaller the opening, the better your oven is at holding heat. If the size of the opening relative to the volume of the oven is too large, it will be difficult to keep your oven at high heat, and it won't hold heat for baking. There is a U.S. made commercial oven that has this problem, and I have heard numerous restaurant owners and pizza chefs complain about it. I had a small (26") oven at an Italian house, and the opening (16" x 10") was too large (relative to the oven volume), and it just couldn't hold heat.

Second, the opening needs to be big enough to easily move food in and out of the oven. If the opening is too small, it can be a pain just using it. I have that problem with my Scott oven.

For the opening width, 18"-19" is pretty standard. It gives you room to work (and as Robert says) see the fire, without over doing it. You can go a little wider, but I wouldn't go past 20". That width will let you get just about any pizza in and out of the oven.

Opening height does depend on dome height, and 60% is an OK rule of thumb -- though it is something of an urban legend. There is no perfect formula, and I have never seen it used in the context of an Italian brick oven. For example, the ancient ovens have really high domes (you can almost stand up in them), so the opening height to dome height ratio on those is tiny. Equally, as brick ovens gets larger and the dome gets higher, there is no reason to make the opening taller than 12"-13" -- the size you need to get a roast in and out. So in that case the ratio of opening height to dome height gets smaller and the ovens simply perform better.

If you have a 42" oven, with a 20" dome, an 19"W x 12"H opening should work nicely. Good access, good thermal characteristics.

If you have a 36" oven with a 17"-18" dome, an 18"W x 11"H opening would be good.

If you are building a Volta Bassa (low Naples style dome), you should bring your opening down an 1" or so -- but makes sure you can still fit in a turkey.

If you want to maximize heat retention, you can always arch your oven opening (higher in the middle for a roast), but lower on the sides for heat retention.

If you are really into maximum design, you can have a local metal fabricator make you a cast iron door opening like this:

http://fornobravo.com/commercial_piz...istorante.html

Wide at the bottom, high in the middle and closed in at the sides. Now that is cool.

James

keleherbill 06-01-2008 12:51 PM

Re: Oven opening size
 
I am having an oven built as part of a backyard landscaping project. My agreement with the contractor calls for an oven with a 36" diameter, 18" vault and an opening 19" wide by 12" high.

The dome is complete and it varies from the recommended dimensions. Although the diameter is 36", the opening is 12.75" high and 20.5" wide. The floor is also more uneven than I would like (the contractor did not lay any fireclay or sand on top of the vermiculite concrete.)

My question is whether the actual dimensions are "close enough" to the ideal that it will work for pizza, bread and other foods, or should I ask the contractor to rebuild at the proper dimensions? I am inclined to just let it go, but thought I would ask for other opinions. If this is a major issue I want it fixed, but I do not want to make the fuss unless I really have to.

Thanks

SpringJim 06-01-2008 04:39 PM

Re: Oven opening size
 
I think you will be okay. Worst case is you could put an angle iron frame in the opening if you are really concerned about it.

I'd document your issue but try the oven first...I think it will be okay.

Funny, I had just read James' old post on door sizing this morning!!!
I'm looking at a door that's 20x12.5 inches and a dome height of 22 inches.

Get a peel and slide it on the floor though....a rough floor could really be a PIA. Might be possible to grind down any rough edges but you want a smooth floor....

Good luck!

thebadger 06-01-2008 05:45 PM

Re: Oven opening size
 
From what I read I think you'll be okay. I would try it and see what happens...

Regarding grinding the floor. I think you want to be careful as a lot were doing this but after sanding the floors would tend to "pit" easier. I think it has to do with taking of the "hard" outer layer of the firebrick.

I would just try to grind down any "high" spots where the bricks meet.

just my 2 cents.

Thanks
Dick

Dutchoven 06-01-2008 08:24 PM

Re: Oven opening size
 
12.75 for an 18 inch dome is a bit high but I think it will be fine...width is not a big issue...you could have the contractors mason run an arch ring of firebrick splits to narrow and shorten the opening...could be left full 1.25" on sides to give you and 18" wide door by 11.5" high...that door height is almost exactly at what is usually the recommended ratio of door height being 63% of the height of the dome
Any chance of photos?
Best
Dutch

gjbingham 06-01-2008 11:29 PM

Re: Oven opening size
 
Agreed. All sounds good. If you can slide a peel in there without getting stuck on an uneven brick, your golden!

Frances 06-02-2008 02:41 AM

Re: Oven opening size
 
How uneven is the floor? Mine is a lot more uneven than some around here, but it works fine.

One option would be to remove the floor, sprinke some sand on there and then replace the bricks again. Fiddly, but not impossible - unless the floor is mortared down? This would probably be better than grinding the bricks.

brokencookie 09-07-2008 11:32 PM

Re: Oven opening size
 
This may seem like a stupid question.... but I'm curious. Is everyone building their transition a uniform height ? All the discussion is about the door opening. I am assuming that you are refering to the opening in the dome ( leaving the heating chamber). What if you put on an exterior door ? My current plans are to use a hindged door at the end of the transition or the exit of the oven. I have a door that is about 12.5 tall by 19 wide. My plan is to mount this in a frame (with hindges) at the exterior. Construct the transition with an arch taller than the door leading back to the oven ( best guess about 18 inches tall). The exit from the actual oven opening would be about 14 inches tall.
This should leave me with a "chamber" too collect smoke and prevent it from exiting the front of the oven. In my mind, having the front door shorter than than oven exit should encourage the smoke to go up than chimney rather than out the front.
Would I then build a 22.5 inch dome to match the 14 inch oven exit ? Or build a 20 inch dome to match the exterior door. I am planing to have a removable "interior" door as well for retained heat cooking.

Wiley 09-08-2008 09:37 AM

Re: Oven opening size
 
1 Attachment(s)
Bruce, I have an issue with smoke at fire up and so I decided to try making one of the baffle doors that lets air in the bottom and makes the smoke go out the chimney because it has no where else to go. Attached is a photo. I made it out of 1/2" Hardibacker and some scrap shelf brackets as it was a prototype. It worked very well save when it reaches 550F the Hardi begins to break down and give off a bad smell. I will construct in steel.

Now to get to your door idea, how will you get the inner insulating door thru the smaller outer door? Not saying it couldn't be done but it will take some clever designing. It is something I have and am considering but at the moment the smoke blocking door seems to work quite well. Perhaps too well as it ducts the incoming air such that it is like someone continually blowing on the fire. It burned wood fast; what would take an hour to burn down normally in about 40 minutes. The heat rose fast as well which for a brick oven might be a downside, with my steel dome I wasn't too concerned.
Wiley

brokencookie 09-11-2008 05:34 PM

Re: Oven opening size
 
Quote:

Originally Posted by Wiley (Post 40715)

Now to get to your door idea, how will you get the inner insulating door thru the smaller outer door? Not saying it couldn't be done but it will take some clever designing. Wiley

Wiley
I figure if I make transistion about 3 inches wider than the actual opening and make the actual oven opening the same size ( only about 2 inches taller). I should be able to insert a door at an angle, and then stand it up to block the entry.
The "inner' door is actually sort of a back up plan. I am planning to make a a full closure damper in the chimney, at which point the outer door will work for air control. If my plan doesn't work, then I will have to make and inner door. I am just trying to make all my design mistakes now rather than during the build.


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