Air Vents

[Robpriddy]

I am building a 36" oven from the Forno Bravo plans. In looking at the design I am wondering why there are no air vents in the sides of the oven. Has anyone tried installing a pipe with damper in the sides of the oven? Is there a reason for not doing something like that? It just seems like having a way to control air flow could offer increased temperature control for the oven. With side air vents, I could close the door and control air using the dampers...air comes in from the sides and out the chimney.

[Gulf]

Re: Air Vents

You may be on to something. I am not one to discourage innovation. But, you can control air induction from a vent/damper built into one of your doors if you want to experiment .

[Ken524]

Re: Air Vents

Interesting question.
The Pompeii design is very efficient. When heating up, the airflow enters through the bottom of the entry, moves across the fire, then flows up the back and roof of the oven before exiting the vent. You can actually watch this circular motion when you fire the oven. This flow of air heats up the oven evenly and quickly.

You'll probably want an insulated door to retain the heat after cooking pizza; you'll have several days of useable cooking heat. You can use the door when firing the oven to partially block the entry if you are firing on a windy day. That's all the control you'll need.

Keep it simple. Once you start firing, you'll understand completely!

[Robpriddy]

Re: Air Vents

Thanks for your thoughts on adding air vents. I will keep looking at it as I move ahead but like the idea of a vent in the door. Good to know that even without a vent I can have good control of the air flow.

Does anyone have two doors, one that goes inside the landing and closes off the oven from the flue and one that goes outside the landing and closes off or controls the flow of fresh air but leaves the flue open to the oven?

[Tscarborough]

Re: Air Vents

Unlike a kitchen oven with this type of oven you do not control the air temperature inside (other than indirectly), you control the temperature of the thermal mass. As designed, there is no lack of air, and the shape maximizes the amount of heat retention in the thermal mass.

For post-fire cooking, you could use the door/vents to control the air temperature to a certain extent, but I am not certain I see the utility. Try it and see, just make sure that the size of the vent(s) are equivalent to a brick or 2 so if it doesn't work you can fill them easily.

[Laurentius]

Re: Air Vents

Cool, dual air vent and a turbo in the chimney, that thing will be "Smokin".

[Gulf]

Re: Air Vents

Thanks for your thoughts on adding air vents. I will keep looking at it as I move ahead but like the idea of a vent in the door. Good to know that even without a vent I can have good control of the air flow.

I choose to only use door vents in order to keep my oven as close to the proven specs as possible. A door is very easy to repair/replace if it does not work. I don't think that air venting will be useful for anything other than the lower temp cooks with a small live fire or coals IE: using the oven as a BBQ/smoker.

Does anyone have two doors, one that goes inside the landing and closes off the oven from the flue and one that goes outside the landing and closes off or controls the flow of fresh air but leaves the flue open to the oven?

I have that set up, but my outside door is paired with a damper in the flue. Controling the exhaust also, seems to be a better option for temp control on the lower temp cooks. At this time, I don't have any data on that to share other, than this set up works great on a low temp 2 to 3 day charcoal curing.

[Robpriddy]

Re: Air Vents

Thanks for all the information...Just had an opportunity to visit a local who has a working oven. Theirs is a little different in design, deeper to hold more bread and more rectangle than circle but still basically the same arch roof and opening.

The interesting thing was in their design in the landing. They had an ash clean-out in the landing and below the flue. They had two doors, one that blocked the oven from all fresh air and held in the heat, and a second door that could be placed to seal the oven but leave the flue open to the oven. Air would draw through the ash cleanout into the oven then out the flue. Kind of the same idea as a vented door without the flow control.

Their comments support what all of you are saying, having air flow through the ash cleanout was an unintended result of their design that is sometimes useful but really not necessary.

They really pushed me to add thermocouplers into my design. My current plan is to use an IR thermometer only. They use an IR but also have 3 sensors built into different depths in their oven walls. The day I visited they had just finished firing the oven and had cleaned out the fire in preparation for baking. The oven was sealed and the three thermocouplers had a temperature reading that was within a few degrees of each other. This is how they know they are "ready to cook" and the mass of the oven has evenly heated to the correct temperature.

The more I learn the more this project is costing me!!

[Ken524]

Re: Air Vents

Hi Rob,

I thought about installing thermocouples; I was really interested in them from a techno-geek standpoint. I chose to skip them because I had read that they aren't really necessary and I'm sort of a purist.

Everything the guy told you about thermocouples sounds reasonable. However, after you use your oven a few times you'll learn it's personality and you won't need them. I have an IR thermometer that I used quite a bit the first couple of months (and I highly recommend one) but now I rarely pick it up. After my dome goes white, I can tell you the temperature of my oven, +-30F, at any time in the next 3 days; no thermometers required . Your oven's cool down curve will be very consistent.

After a few months of regular use, I used my IR thermometer to create a temp graph. This was very helpful for learning the characteristics of the oven, including determining when the oven is fully saturated. Here's what I came up with: http://www.fornobravo.com/forum/f17/...raph-4123.html

Ash Slot: do a search on the forum. Lots of opinions both ways on this. I don't have one and I don't think I need one. Some guys love them.

Ventilation: try not to run into "paralysis of analysis". If you build a standard Pompeii oven and construct a simple, solid, insulated door to seal off the chamber, you'll have all the ventilation options you'll ever need. I promise. The Pompeii oven design is amazing in its simplicity.

Good luck with your build! I'm looking forward to watching your progress.

[Robpriddy]

Re: Air Vents

Thanks Ken....Very interesting & helpful information. The graphs really bring the temperature dynamics into focus. The thermocouplers and digital temperature readouts are really cool but what you are saying makes sense and it saves me $$$. I will give it much more thought before ordering the extra equipment.

Thanks again for all the feedback. Got the floor set and the first course of upright bricks mortared into place yesterday. Feel like I am really started now.

Will start a thread in the Pictures section to document progress. Thanks for following and advising.

[GianniFocaccia]

Re: Air Vents

Hey Rob,

Very interesting question regarding the side dampers. Still trying to picture how the oven would exhaust into the chimney with the door closed. I believe the closest method of 'tuning' your oven has been accomplished on a small scale via a blast door or door with adjustable vents, both top and bottom.

BTW - Nice start to your oven. What are you using for under-floor insulation?

John

[Robpriddy]

Re: Air Vents

Thanks, I am really excited to move from the stand to the actual oven. I am on the outer edge of Sandy and it is windy here today but no rain so I am working on installing the IT to get ready for going up with the walls. Hope to get started by Tuesday or Wed when the storm passes.

The top of the stand is 7 1/2" of concrete and vermicrete. Hope that is enough insulation and mass.

[Robpriddy]

Re: Air Vents

John...I forgot to discuss the side vents. The thought was to have a door at the end of the landing. That would allow the oven to vent to the flue and incoming air would be controlled by two side vents with dampers. So far the consensus has been...interesting thought, probably could work but really not necessary. Original oven design works well and offers plenty of air control.

I have been talked out of trying it but still may make a second door with vents. That is something I can play with after the oven is up and cooking.

[Ken524]

Re: Air Vents

Hi Rob,

I wasn't trying to talk you out of the thermocouples; they do have a very high "gee-whiz, coolness" factor . Just letting you know that they aren't a necessity.

If you think you might want them but are not sure about the cost, just buy the probes and install them during construction. If later you decide on using them, you can buy the expensive control box. Like pre-wiring your house for speakers just in case.

[Robpriddy]

Re: Air Vents

I like that idea Ken. With the wind and rain from Sandy it looks like a may have a few down days so I could place the order and get them in without too much delay. I will sleep on it.