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Heat break. To do or not to do - Forno Bravo Forum: The Wood-Fired Oven Community


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Heat break. To do or not to do

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  • Heat break. To do or not to do

    I'm in the process of closing my dome and have designed the vent. Should I or should I not install a heat break? I still haven't fully grasped the benefits of this.

    Any help would be appreciated.


  • #2
    It depends on what your WFO cooking goals are. If you are just doing pizzas or maybe a roast the next day then calling it good then shutting down the oven then you probably don't need a thermal break. If you want several days worth of cooking, then preserving your heat then thermal breaks are a good option. So it is up to you, but good insulation on the dome and under floor are key and more important than thermal breaks.
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    • #3
      I too searched to find a definitive answer to the benefits of a thermal break, but that would probably require building two identical ovens (one with and one without), firing them to the same temperature, and taking measurements, or a high powered thermal analysis. A builder just has to decide how important it is to do everything practical to make the oven efficient. Like Russell said if you aren't after maximum baking times, or you have an unlimited supply of free wood, you probably don't need one. That said, breaks can be as simple as a gap in the floor bricks that fills with ash and a bit of gasket around the arch, so in the grand scheme of building my oven the extra few hours of cutting the arch bricks to provide a gap and hold my fiber rope was a drop in the bucket.
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      • #4
        Thanks. I plan on using it on a regular basis but no hard core bread baking. I was thinking that if I go with a break that I would built the inner arch 1/4" away from the dome arch and stuff the gap with rope. I would love to avoid as much cutting as possible.


        • #5
          Another way to get the heat break without all the "L cuts" would be to set the outer arch back and over over the inner arch. The gap is between the outer radius of the inner arch and the inner radius of the outer arch. Same amount of gap, with a larger reveal, making the oven more accessible much like the flared entry design does without all the intimidation . Doing that would also allow for a slightly shallower entry.
          joe watson

          "A year from now, you will wish that you had started today "

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          • #6
            Remember that if you plan on using a thermal break in an effort to retain heat it's not all that effective. Iff you only had 1/4" insulation under your floor or over your dome you wouldn't expect it to be adequate in preventing much heat loss. The small gap will slow heat by conduction but plenty of radiant heat will travel that 1/4" easily. Its second function however is to act as an expansion joint allowing the inner parts of the oven to expand without placing stress on the cooler and unexpanded outer decorative arch and igloo shell (if the build uses that style). In ovens without this expansion joint, I've seen enough big cracks in outer arches and dome shells to convince me that it's a good idea to design and build it this way. It's more trouble but very effective. For this expansion joint to work it needs to be filled with material that is somewhat elastic e.g. fibreglass rope, lean vermicrete or perlcrete, CFB etc.Filling the gap with a thick walled stainless pipe may look fancy but it's extremely conductive and quite inflexible.
            Kindled with zeal and fired with passion.


            • #7
              I was thinking more aligns the expansion as well. I'm afraid of an outer arch or vent crack A quarter inch should be good and stuffed with rope.