Can a 3/4 Inch steel plate below oven floor's firebricks not warp if gas heated?

[Harry Damm]

Just sold this house above and I must build a NEW pizza oven. The fireplace insert chamber below, vented up into the traditional pizza oven chamber, and the heat from the wood alone up thru the sole vent in back was amazing for high pizza 800+ temperatures. My next pizza oven I want to heat up faster, and not need to be as insulated under the pizza floor, if I heat the oven floor with natural gas burners! In my new yard, I will build just a unique hybrid pizza oven that is gas fired and could also be secondarily heated in the chamber by hardwood.

The 27" wide floor (3 firebricks wide) and the 45 " deep cooking area (ten deep firebricks 4.5" flat) is a perfect size oven for me, This hybrid goal is to be able to use only natural gas with a 3/4 inch gas line, and heat the pizza oven more quickly by having three huge gas burners below the firebrick hearth, to heat the floor of the oven. The three huge burners come on a 42 inch by 22 inch wide camp-style wheeled cart, that is 36 inches high, allowing it to slide right in the corner under the entire pizza oven. The 2 custom designed industrial built burners in the back and middle of the oven can each have a 100,000BTU rating, and the closest to the front I will order a lesser 40,000BTU burner. The 3 gas pipes under the 3 burners will be over 12 inches down from the burners, so the metal manifold and controls will not be impacted by heated as much. I want to buy a custom cut piece of thick sheet metal, 27" by 45", that is either 1/2 inch thick, or 3/4 inch thick, to have the firebricks sit upon and stay FLAT!

The combined 240,000 BTUs I believe are four times as powerful as some of the marketplace gas jets for pizza ovens I see in the internet. The custom made cart and 3 awesome burners will cost under $900.00. Multipurpose, too! They can heat the floor of the oven, and simultaneously allow heat to go up and around the two sides, thru slots/vents in the firebrick adjacent to the oven's barrel shaped walls. We'd have a larger vent in the back, to best emulate the flames seen in my old pizza oven cooking ribs below.

The warped question I have is this: To keep those 30 firebricks forever flat as they are heated from below, do you believe a 3/4 inch steel plate is a solution that will fit EXACTLY beneath the thirty split 1.25" or 2.5" flat firebricks? Will the 3/4 inch steel eventually warp and not be flat any more with average use a few days a week max? Or is 3/4 sheet metal thickness overkill? Is a 1/2 inch steel plate adequate to do the job?

I know the uninsulated pizza oven floor, with slits along 3 sides to bring heat UP, will also lose heat quickly in the oven when the 3 adjustable gas jets are not on. The beauty of this rolling cart with a 15 foot flexible gas line, is that I can roll out the cart and use the 3 burners for 2 woks, and a lower simmering burner for smaller cooking pans! I can then slide in an insulation board that is 36 inches wide just under the hot metal/brick floor, to help maintain the heat for slow cooking! What do you think?

Thanks for someones feedback on using either the 1/2 inch ($254 cost) or the 3/4 inch sheet metal costing $356,.???



I welcome any other comments on this funky hybrid experiment!
Thanks Best regards,
Harry in Fort Collins Colorado

[Gulf]

Hi Harry,
Welcome to the forum. I'm moving your topic to Other Oven Types. Sorry for the delay in approving your first post. Being a wood fired oven forum, we are still a little touchy about the safety issues concerning gas options. Forno Bravo always advises that:

When making recommendations regarding gas, always recommend using a UL tested (or equivalent) burner that has been tested with the specific oven make, model and size it will be used on.

Gas installations must be certified for the specific application. Indoor is more stringent than outdoors, etc.

Always use a certified plumber to hook up any gas appliance.

This advice from Forno Bravo is a direct response to your post:

This is what would be a hybrid white oven (fire below chamber) and black oven (fire in chamber).

I would caution the builder on over-powering the chamber, extra BTUs, if not burned efficiently would become carbon monoxide.

Flashing is also a major issue.

Some commercial burners on the market go up to 250,000 BTUs, but they are in larger ovens.

Alright Harry, there we have couple of disclaimers and warnings. There may be more coming later in the thread.

Here is my 2 cents. You have some very interesting designs incorporated in your oven. I hope that you get the answers that you are looking for and wish you success in your build.. I'm a wood fired purist so, most of your design is above my pay grade. I do however, play with a little metal forging. I believe that ,over time, even the 3/4" metal will sag under it's own weight (much less the added weight of the brick) unless that it is supported at regular intervals from below. Good luck and be careful Harry .

[Harry Damm]

Thank you Serf, for the good advice. Excellent! My prior wood fired only purist pizza oven was excellent, yet the Colorado city I live in has already banned in-ground fire pits! Sometime soon they will ban ALL fire mechanisms, although a contained pizza oven might be considered safe. The gas idea is to assure me the project will endure. I hope any other forum users can weigh in on this concept of making a hybrid oven! It might be an easier build, if the barrel shaped pizza oven has vents for the heat to rise on just both sides, not the back??? I welcome any feedback and thanks for the consultative ideas!