Help on vent size

[Davy]

My oven is finished with a vent opening 15" in depth from the circumference of the oven to the outside brick on the vent entrance. When I lit a small curing some of the smoke came out the 8" chimney, but most of it by-passed the chimney and came out of the entrance. When I placed a piece of lumber over the top half of the entrance then the smoke all went up through the chimney.

I am thinking of adding another brick (so 2 1/2" to make the total 17 1/2") to the entrance way to add depth to the vent. Does anyone have a reaction to this idea, negative or positive? I would appreciate anyone's input.
Ciao for now,
Davy

[james]

I think a couple of things are going on. First, your oven is still damp, so all bets are off on how it will behave in the long run. Your fires won't be hot for a while, which will result in a little more smoke. Also, your vent area isn't getting hot, and isn't drawing yet. That will also come in time.

Last, there will always be a little unruly smoke when you first fire the oven, which goes away in a minute or two as the oven heats up. But in general, brick ovens burn so hot that there is little smoke after they have heated up -- mostly you will just see hot air sucking up the vent when you are up to heat.

I used to look across the yard at the Casa oven at our old house, and I could tell how the fire was going by seeing the hot wavy lines above the chimney. I got to where I didn't even have to walk over to look.

If you think that an 8" round chimney will draw a 42" oven, I think your 15" vent volume seems safe.

Anybody not agree with that?
James