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  • Thinking about replacing my firebrick floor with refractory concrete and gas-and idea

    I built an oven with a 48" diameter and it doesn't seem to hold heat very well. It takes forever to get up to temperature, less so now that summer is here. Initially I thought it was a crack in the dome, perhaps it still is but regardless, I don't think the oven floor gets hot enough. It seems the oven is mostly top heat. I can cook pizza in 4 minutes or so, but don't like the lack of bottom heat. I am thinking about removing the fire bricks and some of the vermiculite layer beneath and putting in a couple of burners and connecting them to a propane take. I will vent the area and figure out a way to light them. But my idea is to put the pipes in and then pour a floor made out of refractory concrete. The whole thing will be tricky as I gave to get the bricks out, enough of the vermiculite/cement insulation layer to lay some burners in, then get the poured concrete slabs (2 slabs) through the oven door. I plan to set them right on the fire bricks that I will leave around the edges. I still plan on building a fire, just want the additional bottom heat. Am I crazy for attempting this? I just find the current oven very inefficient. Any advise would be helpful.

  • #2
    Re: Thinking about replacing my firebrick floor with refractory concrete and gas-and

    What type of wood are you using to fire it with?

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    • #3
      Re: Thinking about replacing my firebrick floor with refractory concrete and gas-and

      Is insulation an issue? How much do you have and is it dry? I have no idea what your situation is, but it might be easier to address the insulation. What temp do you read on the dome and the floor?

      Mark

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      • #4
        Re: Thinking about replacing my firebrick floor with refractory concrete and gas-and

        As always, gas in enclosed domes is a potential recipe for disaster. 48 is a huge oven, and needs a huge fire. You need a lot of insulation, and it has to be bone dry. In cooking, your floor heat is recharged from the dome, and this is done with a fire that is flaming up the wall of the dome.

        Four minutes is forever in wood fired pizza land. Is your wood dry? Does all (or almost all) the carbon burn off your dome?
        My geodesic oven project: part 1, part 2

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        • #5
          Re: Thinking about replacing my firebrick floor with refractory concrete and gas-and

          Hi...I do use dry wood...it just takes a butt load to get it hot. The temp on the floor is only about 650 but the temp is higher in the dome..this is after 2 hours of a big fire.

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          • #6
            Re: Thinking about replacing my firebrick floor with refractory concrete and gas-and

            Well, I am going to check to see if there is a leak in the dome...but I have 4" of the vermaculite cement under the firebricks...around the dome I have vermaculite and then cement board and rock.

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            • #7
              Re: Thinking about replacing my firebrick floor with refractory concrete and gas-and

              It is not always how LONG you fire the oven, but how BIG the fire is. As Dmun said, 48" is a really big oven...how big is your fire and is the dome turning completely white?

              Drake
              My Oven Thread:
              http://www.fornobravo.com/forum/f8/d...-oven-633.html

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              • #8
                Re: Thinking about replacing my firebrick floor with refractory concrete and gas-and

                Also, how thick is your floor? 1 layer flat bricks, on sides, ect. And how tall is your dome?
                Wade Lively

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                • #9
                  Re: Thinking about replacing my firebrick floor with refractory concrete and gas-and

                  Originally posted by wlively View Post
                  Also, how thick is your floor? 1 layer flat bricks, on sides, ect. And how tall is your dome?
                  ...and how much insulation is under the floor?

                  Two hours isn't a long time to fire an oven. I usually fire my 42" oven for at LEAST 2.5 hours before cooking.

                  A cold floor is typically a symptom of poor insulation underneath or inadequate fire.

                  My guess is that it would take a LOT of propane to get an oven to temperature. Much more costly than wood. I'm with Dmun; I don't think it sounds safe.

                  Let's see if we can troubleshoot your problem before working on the solution.
                  Ken H. - Kentucky
                  42" Pompeii

                  Pompeii Oven Construction Video Updated!

                  Oven Thread ... Enclosure Thread
                  Cost Spreadsheet ... Picasa Web Album

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                  • #10
                    Re: Thinking about replacing my firebrick floor with refractory concrete and gas-and

                    I'm leaning towards your fires not being big enough.....there is big, then there is scare the wife, friends, and neighbors big - that is what my 36" oven needs. I have to believe a 48" oven requires a fire the equivelent of the 3rd dimension of hell...in other words, you should be stepping back saying WOOOOOOW, HOLLY SCHVIT!!!!!!!!!!!!DID I JUST LOSE MY EYEBROWS???

                    RT

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                    • #11
                      Re: Thinking about replacing my firebrick floor with refractory concrete and gas-and

                      For an oven that size I would expect you will need about 2 to 2 1/2 cubic feet of well seasoned firewood. To get an idea of how much that is; the bundles of firewood that are sold at the supermarkets are typically 3/4 cubic feet (check the packaging) - so you would need the equavelent about 3 of them.

                      Try "Pre-heating" with a small "camp size" fire for about an hour and a half then load it up. Fill the oven almost completely with the wood "teepee" style". When it catches, the flames should end up licking outside the vent and the door. This will be a big fire - remember the "plasma god" from star trek ? This should typically burn down to coals in 1 to 1 1/2 hour.
                      Last edited by Neil2; 07-20-2009, 05:04 PM.

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                      • #12
                        Re: Thinking about replacing my firebrick floor with refractory concrete and gas-and

                        You guys are starting to worry me with the BIG fire talk! I was thinking nice slow afternoon, warm fire, red wine, sunset and then a few great pizzas. You guys make it sound like the fire brigade will come around to find out why next doors pet budgie died of heat stroke at 30mtrs.

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                        • #13
                          Re: Thinking about replacing my firebrick floor with refractory concrete and gas-and

                          You've got a large oven, even if it is well insulated it will take a big sustained fire to heat all of the surface area. Remember, you are shooting for at least 50% hotter than any indoor oven or broiler. If your not getting your oven to burn white (all the soot burns off the inside), then your fire just isn't big/hot enough.
                          As for the budgie...don't they taste like chicken?

                          RT

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                          • #14
                            Re: Thinking about replacing my firebrick floor with refractory concrete and gas-and

                            I couldn't eat Tweety so I can't tell you what they taste like.

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                            • #15
                              Re: Thinking about replacing my firebrick floor with refractory concrete and gas-and

                              They taste kinda like spotted owl, especially with some fava beans and a nice chianti.

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