How can I add mass to propane oven without burning out oven?

snowleopard Posted By snowleopard, Dec 4, 2010 at 12:38 AM

  1. snowleopard

    Minister of Fire

    Dec 9, 2009
    Greetings, and thanks for reading this post.

    I have a small-ish (about one turkey-sized) propane wall oven that doesn't do a great job baking. I think it lacks the kind of mass that absorbs the heat and radiates it out to the food--food burns on the bottom while the top of the food cooks. Wondered about adding some firebrick/tile/granite to the floor of the oven, so that it will heat up and radiate the heat to the food, and diffuse the direct heat to the bottom of the food.

    However, I don't want to burn out the floor of the oven/the burn tube/the ignitor by having too much heat massed right there. Alternatives I've considered are as follows:

    Put the brick on a rack in the oven. Downside: I only have two racks.

    Put them on the floor, but put spacers under them so that there's at least a small airspace there. Concern would be that the spacers would be hot spots that would burn out.

    Put them on the ceiling (I"m not sure how to suspend them ) and let the heat radiate down to food.

    Put them on the walls, let the heat radiate from the sides.

    Forget the whole thing and just keep my eyes on the pies.

    Also, can anyone describe the nature of firebrick to me? The last time I saw any was decades ago when I cooked in a wood cookstove (best-baking oven I've used in my life). I remember it as kind of a soft, chalky brick, and wondere if it diffuses the heat better so that it might be a better choice for this application, and if it would be less prone to burning out the metal of the oven than, say, granite might be.

    Also, where does one find firebrick in this century.

    Any ideas/brainstorms appreciated.
  2. EatenByLimestone

    Minister of Fire

    Jul 12, 2006
    Schenectady, NY
    Firebrick can be found at your local cement yard. I don't know that it will help, but it's fairly cheap at around $2.50 a brick so it wouldn't hurt to try it.

    I think I'd try it on the bottom rack with large spaces around the sides. This way it acts as an insulator (What it does best) and forces the heat around the edges to form a convection current. It wouldn't give enough thermal mass to make a difference, and even if it could, heating up the mass with propane would waste a lot of fuel.

  3. snowleopard

    Minister of Fire

    Dec 9, 2009
    Thanks, Matt, for your post and thoughts. With such a small oven, I'm reluctant to sacrifice a rack for this function.

    I tried putting a layer of 4x4 ceramic tile (with the little raised bumps on the back for thinset) on the floor of oven, a single large tile on top of that layer (again with bumps creating a little air gap), and some strips of tiles about two inches wide at an angle where the walls and floor meet. Smelled bad in the original heating phase, and the light tile discolored pretty quickly, but I have boxes of it around, so no great loss.

    I didn't explain myself very well; I'm thinking more of a diffuser than a brick that would be a heat source. I think that the layers of tile with the air gaps may have set up small convection currents, and also served to block the direct heat to an extent. I assume there was a certain measure of evening out the heat because the tiles would retain heat. I baked a few loaves of bread last night and they're good, not overdone on the bottom. I think I'll stick with this for awhile, and just keep an eye on the oven floor for signs of overheating. I may try some of the foods that typically don't cook well for us in it to see if this helps, and if it doesn't, I'll try firebrick.

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