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HELP! Napoli style hybrid steel/brick oven on a trailer

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  • HELP! Napoli style hybrid steel/brick oven on a trailer

    Hi guys!

    I need an advice from someone who's got experience of building low dome woodfired pizza oven on a trailer.

    I've been reading a lot about how to do it, never made one before.

    I already started to build; I was going for a full brick oven at the beginning, but then I changed my mind and this what I came up with........instead of building the dome with bricks, I can use a steel fire pit (see attachment) upside down on the top of the soldiers bricks, supported with some brackets bolted on the base.

    The reason why I choose to go this way is that I realised that it needs to be built perfect to be strong enough to be transported on a trailer, excuse the to be!!!

    And I know is not gonna be as my first.

    I attached some pictures, not every detail is in there, here are some more:

    Internal diameter:100cm

    Dome height:36cm

    Opening, door: 44x22cm

    Flu: straight out of opening 200mm, insulated, 1200mm height with damper

    On top of firepit I am thinking to pour some clay for the thermal mass that the dome (fire pit) doesn't have

    Bottom insulation: Vermicrete 5 cm + ceramic fibre board 5cm

    Insulation around it: aluminum foil and ceramic fibre blanket 50mm x2 held by chicken mesh

    I would really like to get some advice cheeers


  • #2
    Mobile ovens are subjected to a lot of vibration and bumps. Heavy brittle material is a problem. Some builders have reported building brick ovens on trailers and found they rattle to bits pretty quickly. A cast modular oven in a few or several pieces fares better. Some oven manufacturers offer one piece cast domes for mobile ovens for this very reason. The upturned steel fire pit is a pretty good solution to overcome some of this problem, but you'll still have a heavy floor and floor bricks bouncing around. First thing is to fit shocks to the trailer. You may need to get professional advice on both the springs and shocks for the trailer in regards to the total weight.
    Steel inner domes are a bit of a problem because steel is so conductive it both heats and cools way faster than brick or refractory. Adding thermal mass over the steel dome is a solution to increase thermal mass and heat storage, however it presents problems in that the steel, being so conductive will expand well before any material that sits on top of it can. This leads to cracking of the material as well as losing decent contact and thereby poorer conduction heat transfer. If clay is used over the steel dome it will contract and shrink as it dries even before heat is applied. Shrinkage can be reduced markedly by mixing clay with aggregate, lime and cement (homebrew), but that won't stop the expanding steel dome from putting enormous pressure on the added layer. Some builders have suggested a loose mix of sand and heavy aggregate that can move with the expanding steel as a solution, but you'd need to contain it, perhaps by a second larger steel dome over the inner one with the loose aggregate filling the space. This sounds like a lot of difficult work, it may be easier to add the thermal mass layer, allow it to crack and live with the poorer thermal conduction issue.
    Whatever you decide on, please detail your build so we can all learn what works. Some problems in practice turn out to be far less so than predicted. Pushing the envelope helps everyone.
    Last edited by david s; 08-04-2022, 03:21 PM.
    Kindled with zeal and fired with passion.


    • #3
      Thanks a lot for taking time to reply, I really appreciate.

      Yes i could go with a homebrew of refractory cement and clay (what's the lime for? Do I need it?) Layer of 5cm over the firepit; then I could light the oven, let it to crack, and then fill in the cracks with sand?

      Something else I am not sure is how much is the dome (firepit) gonna rust..
      The chimney is gonna be out of the opening (door), so when not in use the oven will be shut with a door so there is not gonna be moisture coming down the flue.

      Any technical advice is highly appreciated

      And yes sure I'll keep posting pictures