Wednesday, July 18, 2012

Brick Oven Mistakes to Avoid

I receive many emails from people who have built, are building, or are planning on building brick ovens.   This is great.  Occassionally, someone contacts me because the directions for the oven they built omitted essential aspects.

The next series of posts (with a break to report on The 2012 Kneading Conference will be devoted to helping home builders avoid very serious and costly mistakes.  I encourage anyone with some spacial understanding and the desire to bake in an oven of their own making to go for it.

Mistake Symptom One: My oven won't get hot.

6" refractory insulation below
The photo above was sent to me by a person who had followed a plan found on the internet for a brick oven.  The masonry work is very good, however the mouth is the same dimension as the interior!  There is no way that the oven can retain heat with so much air exchanging across the masonry.
There is also no insulation under or over the masonry.  This is essentially a fireplace, where all the heat is radiated outward.
Tear it down? Heartbreaking.  I suggested a number of other solutions.
The point is: avoid these costly mistakes.  Here we go...

Since the goal of a brick oven is to 'soak' the masonry with btu's, it would be sensible to do two things:

Keep the flow of cold air from excessively passing over the interior of the oven.

An average mouth opening that works for most ovens is 10" high and 20" wide.

cast refractory insulation over dome prior to outside insulation
And separate the heat-retaining masonry from the heat-sapping environment.

Insulate under and around the oven. Heat leaves the masonry primarily by conduction.  Insulation stops this.

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