When I designed the oven I had certain factors in mind, first was “what materials do you use for a pizza oven?” And. “What is the best design to use for a pizza oven?
The ovens have been designed using an age old tradition, the chimney outlet should be between 60% and 70% of the oven roof height. This enables the oven to keep the optimum amount of heat in while still allowing enough air in for the fire to draw.
We base our pizza ovens around the dome shape. This is the most efficient design and easiest to master your outdoor wood burning cooking skills. There are many factors for this, with the main one being their ability to radiate the heat evenly from above, while storing latent heat in the oven floor.
The dome draws the fire up and over the top of the dome, drawing colder air into the fire. The cold air is drawn in and is heated by the same radiant heat that cooks the top of your pizza. As this cycle gets hotter and hotter the secondary gasses ignite in the roof of the oven, known as the vault, it reaches up to 600 °C. (one of our customers has had the oven up to 800 degrees c and melted a wine bottle in it, but please,don't try this at home)
The door opening has been designed using various parameters. It fits in with using refractory or reclaimed bricks which are imperial as well as being wide and tall enough to take a large oven dish with a large meat joint or bird up to the size of a turkey.
But the main reason is that the design formula has been around for thousands of years, 63% from roof to opening, or there abouts, 61.8% if you listen to Fibonacci. As you can see from the drawing above, I opted to adhere to this formula, just tweaking the opening by having the venturi at a 45 degrees angle, which works out between 60% and 65%. Not only did the design work fine when I tested it, it works fine a few years on. So why change it? The slightly higher and wider door opening made more sense to the British market.
Purchasing refractory materials can be really expensive in themselves, when you add transport and packaging costs to non-bulk order values, they become even more expensive.
We use recycled fire bricks and kiln furniture that are used in the kilns for the pottery industry.
All the materials are hand sorted and then ground in a mill to produce fire brick grog. This is mixed with heat proof high alumina cement, perlite and a special super plasticiser that allows the mixture to keep its strength. Without this the mix would simply crumble as the pores in the perlite drain up the fine cement.
One of the three main factors that I had to consider during design was what I was being asked by potential customers, here are some of the most frequently asked questions.
“How many pizzas can I get in?”
You could get 1, 2, 3, 4 or even 5 x 10” or 12” pizzas, however when the oven reaches 450 °C, a pizza cooks in just over a minute, so managing one at a time can be a challenge in itself. Cooking 20 to 40 pizzas in an hour will keep your guests entertained just by watching you!
I have visited various restaurants with wood burning pizza ovens, and even the busiest had the same reply when I asked the question. “What would you have done different?” “Built it smaller” was the reply.
Our most popular oven, the Milan 750 has nearly ½ m2 of cooking area without wood. This works out at around 2 ½ standard oven shelves. I believe this is enough to supply a good number of guests, while still being efficient enough to light midweek just for a few pizzas, without burning loads of wood.
“Does it have a door?”
When we began we didn’t make doors, there didn’t seem a need. Cooking was usually done while watching the flames and controlling the heat with wood. However, a lot of the ovens appearing on the market had a door, so we do now supply a plasma cut steel door that is insulated and contains a thermometer.
The door does help to retain heat and can be used to bake at temperatures up to 300°C, any hotter and I would recommend not using a door.
What does retain the most heat is a flue damper, this also controls the “burn”. These can be fitted to the flue and we supply ones that are cast iron. You could really be simple and use a terracotta tile (which also keeps the water out) or the drip tray of a terracotta plant pot. Chimney cowls are available in various designs and are available online and we feel it's something of personal choice. Most of our flues are 125mm diameter.
But like all accessories, you could source something for your own design that suits your situation better, say twin wall stainless steel flue, or back to the question “you could design and build your own door” if you would like to put more of your own design element in.
“Can I slow cook meat overnight in a pizza oven?”
This was the hardest parameter to incorporate into the design of the ovens. Mainly because the UK market was new to the idea of wood burning ovens, which we have to agree, mainly come from the warmer Mediterranean countries.
To heat a stone oven up to temperature takes days, to simplify the maths, the denser the material, the longer it takes to cool down. But more importantly in the UK, the longer it takes to warm up. This, along with the affect the outside temperature has on the oven, meant a different approach.
The inclusion perlite in the denser materials creates a matrix that not only retains heat, the perlite insulates the heat, stopping it conducting to the outside.
This means the oven can be ready to cook after 30 to 40 minutes, mainly using the radiating heat bouncing off the walls and floor of the oven, while slowly storing the heat for the convection heat to cook your food at a lower temperature later.
But can this heat last overnight outside countries who’s ambient temperature remains many degrees higher overnight, than in the UK?
So can I put the question to bed, so as to speak? No you shouldn’t in my opinion.
Why would you want to wake up to slow cooked anything at that is ready at 7 o’clock in the morning after a sleepless night hoping all is going well, not to mention the attention that cooked food can create to the animals and insects of the night?
Why not strike the warm oven in the morning and cook a great breakfast, slow cook throughout the afternoon a tagine or other slow cooked meat dish while the oven is still warm, then turn up the heat and fire out pizzas, steaks, tandoori chicken, chargrilled vegetables along with breads to mop up the juices of those earlier slow cooked dishes?
Then, after putting the door on and closing down the chimney, the next morning the oven will take no time at all to cook that lovely wood smoked breakfast for those overnight guests. Just like the one you enjoyed only 24 hours before.