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Problem with insulation along dome/vent/arch seam?? - Forno Bravo Forum: The Wood-Fired Oven Community



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Problem with insulation along dome/vent/arch seam??

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  • Problem with insulation along dome/vent/arch seam??

    Hello everyone-

    Long time listener, first time caller. Wanted to pick anyone who cares to listen brains on an issue I may or may not be having with my oven. I've been firing oven for about 3/4 of a year now, and only recently started to notice that right along the seam between the dome and the vent/ arch it is getting hot - right along the seam it is getting to be around 175 or so on the outside surface of the oven, while inside it is 900+, and this hot spot tapers off as you move away from the seam, with the top and back of the oven cool to the touch. As you can see from my attached photos of the build from last summer, there are about 4 layers of FB blanket on main dome and about 2 over the arch area. Over this a mix of perlite and mortar was applied about 1/2 - 1 inch or so and then over this was additional mortar to hold the river stones, and over that was grout (which is actually cracking towards the front and around the vent and even along the seam I mentioned above). Is 175 acceptable, or is something wrong and I have heat leaking more than it should be? If water is getting into those cracks in the grout, would it negatively affect the insulation (meaning destroy it?). I do not remember it ever getting this hot to the touch. Also, the bricks around the base of the vent are not insulated, so maybe it is those bricks leaking heat into the stones/grout along the seam?

    Anyways, it would be great to hear from some of you pros out there that may have more insight into this than I. Also, if this is an issue, any insight into an easy way to fix it would be much appreciated, or just tell me that I am worrying about nothing and to keep firing.

    Thanks so much!


  • #2
    Re: Problem with insulation along dome/vent/arch seam??

    I suspect moisture is infiltrating that "seam" and reducing the effectiveness of the insulation. I think the covering of your dome is leaking, as would be indicated by the cracking at the front. The problem area would be like the gutter of gabled roof: rain is directed there and may be getting in at that point.
    My geodesic oven project: part 1, part 2


    • #3
      Re: Problem with insulation along dome/vent/arch seam??

      thanks for the insight Dmun. As you can see with this photo, we added river stones and grouted them in. This grout is starting to crack towards the front and around the vent area (and the dome/arch seam) as discussed previously. So at this point would the insulation still be fine as long as it dries out, or does it need to be replaced? Any recommendations for waterproofing the stones/grout to prevent additional cracking?

      Thanks again for any advice -