Could the vent be a heat drain for baking bread?

[Kvanbael]

(My first post. Very grateful to have discovered this forum, and its plans).

This spring it's happening: I'll be building my oven!
It'll be a 40" inner diameter iglo style with a stainless steel flue. For easy reach inside the oven, the vent is kept as shallow as possible (11").

Since it will be used a lot for bread baking, I wanted to avoid the vent to become a heat drain for the dome. So I was thinking of keeping it separate from the dome. The plan is to stop the oven floor at the door and minimise the contact between vent and dome. The idea is to use a custom made stainless steel vent arch (supporting a red brick arch, mostly for decoration) that is attached to the heart and the dome's insulating concrete, but not to the dome itself).

I would very much appreciate your feedback on this design.
Is a heat-draining vent even an issue?

[david s]

A thick brick flue gallery will act as a heat sink draining some heat from the dome. Some designs reduce this by a small insulated gap in an effort to reduce heat transfer by conduction. This works to an extent but won’t stop heat transfer by radiation. Another approach is to reduce the thermal mass of the heat sink. In your design this is achieved by using stainless which is far lighter than brick although it is far more conductive (around 10 x), so whilst you gain plenty by reducing mass, you lose some by increasing conduction. Another approach is to use a castable refractory which can be way thinner and therefore lighter than brick. As you point out a stainless flue gallery enables you to make the entry quite shallow which is a huge advantage when operating the oven.. It’s fabrication is also far simpler than a brick one.