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Design Help - Forno Bravo Forum: The Wood-Fired Oven Community

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  • Design Help

    Hi All,

    I need some help with my barrel / vault style pizza oven

    I have attached a cross section of my design, I hope it makes sense... Orange is clay brick and blue is fire brick .... where should I put the chimney? position A or Position B?

    If i put it at the top of the oven chamber, will this not result in the loss of a huge amount of heat? I see many ovens with this design and it just does not make sense to me ...

    Thanks for the Help in advance

    Neil
    Attached Files

  • #2
    Re: Design Help

    It is best placed at position A in my opinion, because you get better heat circulation and more even heating, but it will work if placed at B. The fire has a tendency to rush straight to the flue exit. However you need to construct a damper in the flue if placing it at B so you can choke and shut off air and smoke flow and hence heat loss out the flue. The big advantage of the flue in the B position is that you don't need an entry to have to work past, negating the need for extra long handles on your oven tools.
    Kindled with zeal and fired with passion.

    Comment


    • #3
      Re: Design Help

      Thanks David, makes complete sense to me now, My gut said go with position A and thats what I will do, thanks again

      Neil

      Comment


      • #4
        Re: Design Help

        Hi Neil, this is Neil, a South African living in California.

        Are you absolutely sure that you want to build a barrel/vault oven? I started down that path and then switched to a Pompeii.

        My build is here if you are interested: http://www.fornobravo.com/forum/f8/3...nia-19283.html

        Comment


        • #5
          Re: Design Help

          Hi Neil,

          Thank you for the concern, This is not something i have jumped into without thought, although i will admit that a fair chunk of todays working day was consumed by re-reading up on the subject of barrel vs Pompeii. In the end i think i will be sticking with the barrel design.

          I am not going to enter the fray in terms of what oven is best for a pizza, but for me i am looking for a home style oven which will cook a great pizza but will also work for roasts baking etc. If i was interested in singularly making Pizza then pompeii would be the obvious choice

          Comment


          • #6
            Re: Design Help

            Sounds good, Neil! I just wanted to make sure you understood the difference and it sounds like you do.

            Good luck and you are in the right place for asking lots of questions!

            Comment


            • #7
              Re: Design Help

              Right

              Time for the next question

              Thank goodness for a forum like this

              I have been reading up about the base for the oven and the different layers that i need.

              Attached is a pic of my design (this is a cross section across the width) any comments would be appreciated

              red = fire bricks
              Orange = clay bricks
              blue = vermiculite concrete mix (6:1 V:C)
              Grey = re-inforced concrete slab / supporting walls

              have i provided for enough in terms of insulation ... the Vermiculite layer will be about 6 inches thick?

              and in terms of a heat sync will the firebrick and clay bricks be enough?

              I am very aware of getting the base right, knowing i can add insulation to the dome but once the oven is built, nothing can be added to the base ....
              Attached Files

              Comment


              • #8
                Re: Design Help

                I reall couldn't tell by your sketch if you understand that the dome and floor have to be totally incapsulated in insulation and separated from any face brick or concrete which may leach away heat. My sketch is of an igloo, but the priciple is the same.

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                I don't care what folks say behind my back........They are either braggin' or.......lyin'


                My Build
                My Picasa Web Album

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                • #9
                  Re: Design Help

                  Originally posted by Gulf View Post
                  I reall couldn't tell by your sketch if you understand that the dome and floor have to be totally incapsulated in insulation and separated from any face brick or concrete which may leach away heat. My sketch is of an igloo, but the priciple is the same.

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                  Well there is a spanner in the works

                  Thanks for the heads up Gulf

                  Makes complete sense though... I will modify my idea to accommodate and repost

                  in terms of the walls and floor of the oven I have a firebrick layer (25mm thick) followed by a clay brick layer (100mm thich), on top of this would be the insulation

                  is this enough of a heat trap?

                  Comment


                  • #10
                    Re: Design Help

                    A revised design reflecting the text above

                    any comments on the design ?
                    Attached Files

                    Comment


                    • #11
                      Re: Design Help

                      Neil,

                      I have been following your thread with Gulf, he knows what he is talking about. Vcrete is a decent insulator but not as effective as CaSi board (floor) or ceramic fiber blanket (dome) so the Vcrete has to be thicker to achieve the same level of CF thermal insulation. Nothing wrong with Vcrete, just to plan accordingly for the added thickness. I have 4" CaSi/FoamGlas on floor and 3" of CF plus 2" of Vcrete on dome. Oven holds heat for 4-5 days with outside of dome at ambient air temperature.

                      Comment


                      • #12
                        Re: Design Help

                        Originally posted by UtahBeehiver View Post
                        Neil,

                        I have been following your thread with Gulf, he knows what he is talking about. Vcrete is a decent insulator but not as effective as CaSi board (floor) or ceramic fiber blanket (dome) so the Vcrete has to be thicker to achieve the same level of CF thermal insulation. Nothing wrong with Vcrete, just to plan accordingly for the added thickness. I have 4" CaSi/FoamGlas on floor and 3" of CF plus 2" of Vcrete on dome. Oven holds heat for 4-5 days with outside of dome at ambient air temperature.
                        Thanks for the info mate !

                        I cannot find anything other than Vcrete so i think it will have to do ....

                        What do you think of the clay brick and firebrick layer?

                        Comment


                        • #13
                          Re: Design Help

                          Just curious, why are you using 1" firebrick plus a layer of clay brick? Seems like a lot of extra work; you are essentially building two domes. Why not just using a single layer of full firebrick. I am guessing either cost/availability of full firebricks.

                          Also, is your slab supported in the middle in any way?

                          Comment


                          • #14
                            Re: Design Help

                            Neil,

                            I believe you are building a barrel, so the two layers are not near as complex cutting as a dome. The total brick thickness is just under 5" so a little thicker on the barrel and quite a bit more on the floor. It may take a little more fuel to fire the oven but you use what you have to work with. I have no scientific documentation but the word of mouth is Vcrete is about 1/2 the thermal efficiency of a CF blanket. So 6" Vcrete equal to about 3" CF. Again, like Gulf says and your latest sketch, insulate the barrel, floor, and walls away from the reinforced concrete hearth.

                            Comment


                            • #15
                              Re: Design Help

                              Originally posted by jeeppiper View Post
                              Just curious, why are you using 1" firebrick plus a layer of clay brick? Seems like a lot of extra work; you are essentially building two domes. Why not just using a single layer of full firebrick. I am guessing either cost/availability of full firebricks.

                              Also, is your slab supported in the middle in any way?
                              Cost is the driver here, a full firebrick is around $3 here whereas a tile is around $0.60 so a massive difference

                              Comment

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