How much wood do you usually use?

[Rocko Bonaparte]

I'm having a theory that I'd use the same amount of wood in a 48" brick oven as I used in my old 34" tall fireclay contraption; I had to generally fill if halfway with wood to eventually hit 900F/480C. But I figured I'd ask here in regards to reaching that temperature:

• How large is your oven?
• What material are you using in your oven?
• What is your oven's shape?
• What kind of wood do you use?
• Roughly how much volume of wood do you use?

[david s]

All things being equal like moisture in your wood and the chamber temperature you'd expect the fuel consumption would be directly proportional to the combustion chamber volume (internal oven volume), similar to the fuel consumption of a 2 litre motor compared to that of a 4 litre, although it won't be quite double the consumption because the larger motor usually does not have double the weight to push around. My 21" diam oven used 4 kg of wood to get the whole oven white when I measured it a couple of years ago. This was with a perfectly dry oven and dry wood. Because of the maths a small increase in diameter means a massive increase in volume and therefore fuel consumption, although the larger the oven the more efficient because the door is a smaller proportion of the internal surface, so there's less heat loss.

The amount of wood consumed is better measured by weight rather than volume as the energy in the wood is directly proportional to its weight rather than volume.eg. more energy in the same volume of hardwood than softwood.

[jonv]

As David said, it must be related to the volume and efficiency of the oven, but I'm not sure what was meant by chamber volume - the volume to the inner surface of the brick or to the outer?

As noted, a modest increase in the size results in a much larger increase in volume, but the thermal mass is not increasing by the same factor as the volume of the chamber, wherever that measure is taken from.

(Forgive me if these numbers are dodgy - they were just quick jottings!) To get a idea, take two hemispheres with internal diameters of 600mm (24") and 1200mm (48") with 100mm (4") brick. The volume to the inner surface increases by a factor of 8, but to the exterior surface by a factor of only 5.3 and the volume of brick by only 3.4......

The interior volume must have an effect but I would guess it's the volume of brick that is most important. Maybe I'm wrong but that makes sense to me.

Thus with all other factors being equal my guess would be that a 48" oven would need roughly twice the amount of wood of a 34" and perhaps four times that of a 24"......

Warm up times are probably quite similar though - my 1.2M dome is ready in about 1.5 hours.

[JAG]

Rocko,

I have an FB Casa2G100 on a trailer (Fire Within) and do a farmers market where we make ~180pies in 3hrs. I typically heat the oven for 2 hrs to really saturate the oven and try to maintain 750-800 degrees for 3 hours of baking. I usually try to hit over 900 to start and let the oven settle to my 800 cooking temp. Floor temp is hard to maintain due to quantity of pies but for a total of 5hrs of firing I go through typically one Sterilite 18gal. bucket of wood plus a couple sticks. I use mostly ash with some oak.

My home oven I built is not as efficient as my Casa but I don't know how much wood I use as I just pull from my wood stack.

John

[cowolter]

Last week I was doing 6 large pizza's in 90 secs each.
The oven is 80cm internal diameter and I used approx 11kg of wood, excluding kindling.
I Use hardwoods only
I have a 15 ton speeco that is seldom stopped https://cozzy.org/best-log-splitter/ Very easy to maneuver around the yard by hand and fits in a smaller space in the garage.