This seems to be one of the bits of the book that could be improved in the next edition.
Yesterday, I got it again in this lovely note from a lady named June:
I am a 68 year old woman making my first mud oven following the design in your book – I’m really excited about it, and have a question. Does the width of the door matter? A friend gave me a beautiful peel ahead of the oven and it is 16 inches wide. I am making a 27 inch oven and would like to know if an 18 inch wide door would work. I am planning a brick arch opening. I couldn’t find much in the book about the width, only the height.
Many thanks for the wonderful book and all the inspiration and instruction it has provided.
The topic is covered, albeit briefly, in various places in the book, but it’s worth expanding on. What matters most (as with most things) isn’t really size so much as proportion.
An extreme example for illustration’s sake: If you build a 27″ round oven with a 27″ door, you end up with an open half sphere — which won’t be able to capture and hold the heat as well as the same size oven with a smaller door. So for round ovens, I suggest that the door should be no wider than half the diameter (about 13″ for a 27″ oven).
However, if you stretch your circle into an oval, a bigger door won’t throw the proportion off so drastically. Here are the numbers:
a 27″ round oven has about 570 square inches of floor space, and about 85 inches of perimeter wall; a 13″ door demands about 15% of the total perimeter, while an 18″ door takes about 21%.
An oval oven with the same floor space would be about 18 x 31 inches â€” but with a proportionally longer perimeter length, thus allowing for a wider door with less potential for heat loss through the doorway.
To avoid the math: just re-arrange your floor bricks on a flat surface until you get a shape you like, that allows you to use the size of peel you want while minimizing heat loss through the doorway.
You can also, of course, cut down your peel by a couple of inches, and go with a 16″ door, for an oven 16 x 35. Big pizzas are harder to handle, and since things cook so fast in a hot oven, you may find it easier â€” and more fun â€” to make smaller pizzas.