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Vent and landing design questions - Forno Bravo Forum: The Wood-Fired Oven Community


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Vent and landing design questions

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  • Vent and landing design questions

    I am in the process of designing the vent and landing for a Pompeii 42" oven and there a couple of things I am unsure of.

    A thermal break will be installed in between the oven entrance arch and the inner arch. I am planing for a vent of 10.875"W and 5.5"D the outer arch is 23" w 15" h and the entire depth of the landing will be 15.5" . The oven opening is 20 w x 12.5 h and the reveal is 1.5". Is this this size adequate for a my oven size. Also I have run out our floor insulation for the last 5 inched of the landing. Would it be a problem if the outer arch bricks touch the concrete hearth? I don't want to have to purchase another block of insulation for 5 inches.


  • #2
    Good questions Plokuta!

    Since you've planned a heat break separating your cooking floor from the landing, the last 5-6" of landing being without insulation will not be a problem.

    Your chimney vent should be more than adequate since it calculates to just under 50 square inches and that's roughly equivalent to an 8" diameter stove pipe (that's usually recommended for your oven size).

    Assuming your inside dome height is going to be just under 20" (for the target 63%, opening height/inside dome height), the opening height & width specs look good...no problem getting a full sheet pan or large turkey roaster in

    Make sure that you plan for a smoke collection chamber (just outside the oven opening that is larger than your actual chimney vent). You want the smoke flow out of the oven to be collected and funneled up into the vent...not be forced out the front arch peak. The hot gasses that are escaping out of a firing oven will come out at an angle and you want that collection/funneling hood to catch it...think of the hood over a house range/stove. The hood should have more depth (out from the oven opening) than extra width because of the direction of the escaping hot gas/smoke). Usually the hood "happens" just by connecting the arch to the smaller chimney.

    Hope this helps, and remember that this is the time to be asking any of those "I am unsure of " questions.
    Last edited by SableSprings; 10-27-2017, 11:25 AM.
    Mike Stansbury - The Traveling Loafer
    Roseburg, Oregon

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    • #3
      If the oven is a true hemisphere, then the radius of 42" oven will be 21" and with a 63% rule of thumb oven opening ratio, this will be abt 13.25". With a 12.5" high opening and a 21" dome radius, the ratio works out to be 59.5%. Since you are in the planning stages, is there any reason not to shoot for the 63% ratio? I second, Mikes comment on not needing to extend the floor insulation any further. Also second, Mike, with a 5.5" deep vent you will need to flare this dimension to match the ID of a 8" chimney.
      Build Link............... Picassa Photo Album Link


      • #4
        I'm in the process of closing the dome and have already completed the dome arch. Its actually just 13" high so I'm about 62% so I hope it doesn't negatively affect the flow. There is a smoke chamber that leads up to the vent. I have a picture but for some reason I can't post it, its easier to see than explain.

        Thanks for the help. Much appreciated.


        • #5
          I was able to add a picture of what Im planning. From side to side on the bottom is 23". There is an outer and inner arch of 4.5" each


          • #6
            Not sure what you mean that there is a outer and inner arch of 4.5" each. By the looks of the S vent depth (which is coming quite popular), it looks a lot deeper than 5.5" as stated in an earlier post, looks closer to a full brick depth. This is good for mating an 8" chimney.
            Build Link............... Picassa Photo Album Link


            • #7
              Those are a full brick. I was thinking of cutting them down to 5.5" but I cant cut them to any length. I meant that the outer an inner arch bricks will add 4.5" in depth each. So if I go with a full brick in the smoke chamber it brings the total depth of of the entry of 18" plus a decorative arch. Seems big.


              • #8
                Russell, I believe the 4.5" refers to the forward and aft vent arches, which will sandwich in the serpentine vent.
                Plokuta, if you plan to build the vent without a form or template (like I did) you really need to make sure that your mortar thickness does not push your bricks too far towards the center giving you an opening smaller than you planned. I had a bunch of .25" shims I used during my layout to help me visualize the placement. I have never seen this type of vent that was not mating with a hemispherical arch so I am not sure how that will come out, but I think it is going to be a little taller than you are showing with your dry fit. Do you have a picture of your dome and dome arch you could share?
                Last edited by JRPizza; 10-27-2017, 04:04 PM.
                My build thread


                • #9
                  Here is the dome arch. I'm planning on the inner arch to be 1.5" larger for the reveal.