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How small? - Forno Bravo Forum: The Wood-Fired Oven Community


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How small?

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  • How small?

    It seems that larger the oven the larger the cost to build and fire.

    As a person who lives in a household that has 2 adults and one child (12 years)

    It seems the need to cook for lots of people will be infrequent.

    While a big oven may give bragging rights and perhaps make up for other things

    If I am only going to cook 2 or 3 12 inch pizzas or a modest roast and a loaf of bread how big an oven is really needed.

    Are there disadvantages to a small oven other that the modest amount that can be cooked in them?

    Is temperature control more challenging for instance?

  • #2
    Re: How small?

    Petanque, The size of the oven does relate to the dollars spent on materials, labor and firewood needed, but not to the degree that you might be envisioning. An example would be the cost of 100 firebricks or an extra day of labor to build, if any. As for the cost of the firewood, I’m sure that there is some 20% less I can’t say..

    I think that the ability to use the oven any time that you want is more important than size. Any oven you build take your time to get the work area right. It needs to be comfortable in all of your weather, shade from the sun, protection from wind and rain and area lighting that allows you to work at the oven and enjoy your guests. By the time you do these things the cost of a few more or less oven inches becomes a minor cost how the oven fits your lifestyle is key..

    I built a 43” oven with the idea that I might host a 30 plus person party occasionally and might need the oven space to roast a small pig, lamb or couple of standing rib roasts plus all the fixings. I’ve only once used it for a party of 20, but know that a party for 30 wouldn’t be a problem as far as the oven goes. If all you want of a WFO is to cook a roast and all of the fixings for a maximum of 10-15 persons, a 36” inch oven will do you proud!! As for Pizza, as long as you have the about 3 times the diameter of the pizzas as an oven diameter, you should be fine. Why 3X, 1/3 for the fire 1/3 for the pizza and 1/3 for space between the pizza and the fire.

    As for temp control, the oven mass makes control less of an issue than you might think. Getting the oven to pizza temps is a 2 hour burn, some say more or less time is needed; bread is baked on the cool down as are other items. The time to cool down to the temps you want for these, other than pizza foods, will take you a little time to discover. I see this as slow food entertaining, so I schedule a bit more time with friends to allow for the variances of the oven and food is needed and enjoyed.


    PS Playing Petanque or Bocce is a great way to enjoy time with friends.
    Last edited by SCChris; 03-08-2012, 07:28 AM.


    • #3
      Re: How small?

      I think I remember some around having ovens as small as 28 to 32 inches, if these sizes fit your lifestyle, go for it. I have wondered about how I might use a second, mini oven as an adjunct to the large one.



      • #4
        Re: How small?

        I'm a fan of small ovens. Their advantages are numerous.

        1. You don't need a bomb shelter to house it.

        2. Smaller means less weight, cost and faster build time.

        3. Lower fuel consumption. Fuel used is related to chamber volume so a 25 % increase in diam = 100 % increase in volume/ fuel used.

        4.you use a small oven more frequently. No trouble to fire up and cook just two pizzas.

        ( I can cook for parties of up to 30 with ease and my oven is only 21") My oven (when dry) takes only 4 Kg wood to reach 350C in 1.5 Hrs

        6. most folk only cook one pizza at a time anyway, the prep takes longer.

        7. A small oven doesn't take up half your backyard.

        8. If you need more oven you can always supplement with your normal kitchen oven.

        9. You don't require long handled tools that are likely to clock some poor kid in the head.

        10. less emissions into the atmosphere.
        Last edited by david s; 03-09-2012, 12:42 AM.
        Kindled with zeal and fired with passion.


        • #5
          Re: How small?

          the only people who think Adelaide is a country town are those who live in Sydney or Melbourne.

          I was thinking about 800mm across.

          @ wotavidone if you wanted to host a wood foraging weekend it could be popular.


          • #6
            Re: How small?

            I've never paid for any wood. It's everywhere if you open your eyes. Try asking council workers who do tree work to cut you some thin slices, which split more easily, then store them for a year to dry. I also used to collect fallen branches (nothing bigger than a wrist) when walking the dog. Unfortunately he's dead now but these fallen branches (hardwood only) are great to burn and don't require cutting. You just stomp on them or use the fork of a tree to break them.
            Kindled with zeal and fired with passion.


            • #7
              Re: How small?

              I have built both 24 inch and 28 inch ovens...I like the 28 inch better as I have a little more room between the pizza and the fire.


              • #8
                Re: How small?

                In theory, as the 28" is 20% bigger in diam. it will have a 73% bigger oven chamber, assuming both are a hemisphere. This means 73% more fuel consumption too.
                Last edited by david s; 03-09-2012, 12:39 AM.
                Kindled with zeal and fired with passion.


                • #9
                  Re: How small?

                  is my biology training now showing as things get bigger the surface area to volume ratio changes.

                  when it comes to animals small animals expend a lot more energy just keeping warm.

                  wile intuitively it seems sensible that big ovens will require more fuel/heat is it a direct linear relationship with volume?


                  • #10
                    Re: How small?

                    Lilliputian physics explains why spiders legs are so skinny compared to those of an elephant. But the difference in the size of a small oven to that of a large one is no where near as different ,so it hardly counts as a factor IMO
                    Kindled with zeal and fired with passion.


                    • #11
                      Re: How small?

                      I just measure my kitchen oven ,just your bog standard gas designed to fit I suppose into a kichen cupboard module space....measured 470mm x 470 (19 in) floor area.
                      Say count in another 250 mm( 10 in) for a fire and the curve of the wall makes it 720mm (29 in ) to get a WFO to match your kitchen oven roughly

                      Regards Dave
                      Measure twice
                      Cut once
                      Fit in position with largest hammer

                      My Build
                      My Door


                      • #12
                        Re: How small?

                        Thermal mass is going to be a better messure of firewood used to get to temps.

                        A 42 inch uses the volume of 154 bricks this excludes the entry opening of the oven and includes the floor.
                        A 38 inch uses the volume of 127 bricks and has 82% of the thermal mass of a 42"
                        A 28 inch uses the volume of 71 bricks and has 46% of the thermal mass of a 42"

                        I haven't done the math on the surface areas to calculate relative areas of the exteriors to compair the potentual heat loss differences.



                        • #13
                          Re: How small?

                          I would think heat loss would depend on insulation quality and how much food is being cooked.

                          There would be several variables so that getting a precise answer seems unlikely.


                          • #14
                            Re: How small?

                            the curve of the wall makes it 720mm (29 in ) to get a WFO to match your kitchen oven roughly

                            I always wondered about this in order to properly plan plan meals for a large group, but secretly also to be able to defend my WFO against any visiting housewife attacks. Of course, one would have to install racks into the WFO to maximize relative capacity, but allowing for the WFO's thermal properties is another entire discussion.


                            • #15
                              Re: How small?

                              Speaking to the aspect of comparative functionality of your home oven and a small WFO. I have a 30 inch range, a single oven with an integrated 4 burner cooktop. The useable interior area of the oven is 20inches wide by 16 inches deep and 12 high this allows for an inch of air flow around all sides of whatever. Most interior ovens will heat to 550F and this is plenty high enough to bake hearth breads and roast any meat, so a major WFO advantage is higher temps for cooking something like Naples style pizza and that you have a second oven.

                              Allowing for a inch of space on all sides, the usable floor area of my kitchen oven is 320 square inches and this is about the same as a 20 inch diameter circle or what a 22inch WFO would give you. When you’re burning a fire maybe ? the floor is available in a WFO for cooking pizza but when you’re done nearly 100% of your oven is available to cook.

                              Percentage of usable floor space, without a running fire and less an inch on all sides, for a given WFO diameter when compared to a 30 inch kitchen oven.

                              20 80%
                              24 119%
                              28 166%
                              32 192%
                              38 318%
                              42 393%

                              Remember that there are other advantages and disadvantages that a WFO has, that a kitchen oven doesn’t, weather and entertainment are just two examples.