vault opening vs outside opening

[mrgweeto]

I know that the vault opening is critical to proper fireing...60% of the interior dome height. (ex. 21" dome height gets a 12.6" vault opening). I have seen several pizza ovens recently and have noticed that there has been smoke residue on the outside of the outer opening face. When looking at the possible causes I did notice that the outside opening was taller than the dome opening. I could see that there was no smoke ledge to keep that from happening. Would it not be better to have the outside opening slightly lower than the inside so you would get a better airflow going up the chimney from the inside out. Any thoughts on this would be greatly appreciated.
mrgweeto

[glennb]

Re: vault opening vs outside opening

I debated this during my build too, but ended up omitting the smoke ledge for the sake of ease of access to the oven.
A smoke ledge, or outer arch lower than the inner one, would make it very low to see inside the oven and place wood/pizza/food etc and I didn't want to risk having a WFO that was difficult to use for any reason.
Also, the smoke is typically only at startup for me, so it's not that big a deal and the soot can always be washed off.

Another consideration would be to check how deep your entry vault is going to be as this may also impact on which design you use.

[mrgweeto]

Re: vault opening vs outside opening

Thanks Glen. The opening to the vault is 21.6" high and 18" wide I will probably make the outer opening wider by several inches (any thoughts on that) and keep the height the same;21.6"

[DrakeRemoray]

Re: vault opening vs outside opening

If you cast or build a large vent/ smoke collection area in between the inner and outer openings, you have less chance of getting smoke out the front. If you just put a piece of flue pipe on top of an arch, a lot of smoke is going to slip by that...

Drake

[mrgweeto]

Re: vault opening vs outside opening

Thanks Drake. That will make the throat (outer to inner opening) a little longer but maybe not by that much. Before I changed my fireplace over to propane I would simply light one piece of newspaper, open the damper and hold it in the flue and I never got any smoke in the house while the fire was starting to get up to a good burn. I would imagine that would work in this case also.
G