Newbie with stupid question

[Bert]

Hi Folks

I noticed that the chimney flue is outside of the door arch. Why is this the case? Does it draw better?

Thanks

Bert

[david s]

The chimney in front of the dome is the best set up IMO. For my first oven I placed the flue in the centre of the dome with no flue pipe. This is the same set up as a Roman kiln used by the ancients. It drew really well and there was no entry to have to work past and much simpler construction. Saw two ovens at Pompeii using this design.The downside was that you have flames shooting out the flue hole and they are wasted heat. The second oven I built I placed the flue near the door but still inside the oven. I finally built one with the flue at the front and outside the actual oven.a couple of thousand years Roman ingenuity can't be wrong. It is the best IMO.

[Bert]

Thanks David. How did your second oven draw? Bert

[david s]

My second oven did not draw as well as the first. When you are using the power of your flue to bend your flame sideways there is more smoking at start up. The flue will only start working once it has warmed up. This does not happen with the central flue design where the smoke heads for the flue at the top of the dome in a direct path vertically. I also had my flue (second one) exiting the oven without any funneling into the flue pipe. This is important so the smoke has somewhere to gather and the direction change is not so severe. It is like a car with extractors rather than the standard manifold.

[Lburou]

Bert, I would venture to say that positioning the flu outside the arch traps more heat inside the dome....That is what you want for higher oven temperatures, smaller fires and less wood consumption.

Originally Posted by Bert

Hi Folks

I noticed that the chimney flue is outside of the door arch. Why is this the case? Does it draw better?

Thanks

Bert

[dmun]

There are modern ovens, the south american "hornos" that have the flue inside the dome. We've seen people try this plan, and it's really bad for fuel economy and heat retention. The masonry oven basically works with a circular path for combustion gasses, with the air coming in from the bottom of the door, circling around the dome, heating it, and exiting through the top of the doorway. If you interrupt this path, you lose a vast percentage of your heat up the chimney, and loose the ability to retain heat for things like bread baking.

Experience shows that you're better off having no flue than one in the top of the dome.

[GianniFocaccia]

So do these magnificent round Italian commercial ovens (the kind with the gleaming tile enclosures) route the flue from the front or do they come straight out the top?

[dmun]

So do these magnificent round Italian commercial ovens (the kind with the gleaming tile enclosures) route the flue from the front or do they come straight out the top?

They have an angled flue path from the front. The center venting is simply for aesthetic reasons.