So much smoke

[Miranda Richter]

Our pizza oven produces so much smoke out of the front. We're not sure what to do. I've read the forums. We've bought kiln dried wood then dried it further in the oven. We've cured the oven over several days / fires yet the entire inside is black. Is the chimney not long enough. Currently it is about 4" diameter, 12" long. So much smoke is billowing out the front we aren't even able to be outside. Help?!

[david s]

There are a number of reasons ovens smoke.
1. wet wood
2 wet oven
3. inadequate flue
4. over filling the oven chamber with wood
5. poor oven design
6. bark on wood
7. wood too large

It sounds to me like your oven is probably still wet. Is it new? All ovens will smoke if new and wet until you get to the point where the moisture has been driven out. A 4" diameter chimney is inadequate for even a small oven. Mine is only 21" in diameter with a 5" diameter flue and draws extremely well. Unless yours is smaller than mine, my guess is that your flue is inadequate. Making it taller will increase the draw a bit, but a larger diameters a far greater effect. Until you get to the point where all the black soot burns off internally you can consider your oven not properly dry.

[Miranda Richter]

David- thank you so much for your reply, there are two things that you said that I think may be our problem(s). I think the combination of overloading the oven with wood and the small diameter & length of the chimney is our biggest problem! Really appreciate you taking the time to reply to my post!

[Les]

I believe David nailed it. A 4" flu is incredibly small. To dial it in a bit, what size is your oven and how wide / high is your oven entrance?

[Alomran]

My oven is 195cm internal diameter. Would you say a 7" chimney is OK for that size?

[jonv]

I believe that is insufficient. I'm sure someone will correct me if I'm wrong, but the recommended flue for a 42" oven is 8". I have a 120cm/48" oven with an 8" flue and it works fine but I would think you'd need more at your size.

[david s]

I believe that is insufficient. I'm sure someone will correct me if I'm wrong, but the recommended flue for a 42" oven is 8". I have a 120cm/48" oven with an 8" flue and it works fine but I would think you'd need more at your size.

That's correct, a 42" oven needs an 8" flue, but at 190 mm diam. the volume of the chamber is 1.8 cu metres which is almost 6 times the volume of a 42" oven. I would think you'd probably need at least a 10" maybe 12" diam. flue.

[cowolter]

I started my oven experience with some wood that could have been drier and it caused more smoke than needed. The next load of wood made things much better. I try to maintain a habit of loading the (emptied of ash and ember) oven a day or so after firing it with wood, packed to the max, and close the door. The heat (say 150 -200 when I do this) dries the wood out even more. For me, an ovenful of wood is right about what I need for a firing.

The nastier smoke lasts 20 - 30 minutes and then "clears up." I have also learned to use a lot of kindle when I start it. If I use lots of little scraps of kindle and pine strips from my wood supplier, then I have much more certainty of a fast, more complete fire and the smoke is minimized. Then, I do not load it up with too much wood too soon otherwise it is like starting over.