Tuesday, April 9, 2019

Catching the Flue

The placement and the design of the brick oven flue is critical to the function of the oven.

I have heard and seen many mistakes made in this area, mostly due to the assumption that a brick oven is some kind of fireplace.  It isn't.

The goal of the brick oven is to contain the heat from the fire in an isolated chamber.  If air passes through the chamber on the way out of the oven i will be difficult, if not impossible to get the oven to temperature.

Some historic ovens in some cultures don't have flues.  The smoke simply pours out of the chamber and drifts off.  This is okay if the oven is located where abundant smoke doesn't effect the baker.

But nearly all European style ovens, the design that was brought to north America, have flues.
The white oven above is a traditional old Greek oven, no flue and low to the ground.  The oven at the top of the post is one I designed and built for a customer who was born in Greece and wanted it to feel like ones she remembered.  It incorporates a flue so that the baker isn't cloaked in smoke.

Technically, the flue is the hole at the top of the arch between the mouth (the dome entrance) and the face.  The mouth arch allows you to shut the oven entirely with a door.  The dimensions of the flue are in proportion to the oven and the chimney  For instance, if the chimney is to be an 8" by 13" flue tile, the opening needs to match.  If it is a stainless steel insulated pipe, then the area needs to match.

Indoor ovens, as I design them, have dampers (and not incidentally channels that bring air from outside of the space).
Indoor ovens need to have a good draft as excess smoke is not welcome indoors.  Both the diameter of the flue and the height of the chimney contribute to good draft.

Often, you can feel the natural draft even before you light the first fire or you can light a candle and watch the flame being pulled upward.

The actual techniques for constructing the flue opening vary depending on the size of the oven and the materials.  Refer to past posts for details on arches, mouths, faces, cutting bricks etc.

Good draft means no soot on the face