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Pizzas per hour (heat loss)

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  • Pizzas per hour (heat loss)

    Hello wood-fired folks,

    We're having a capacity issue at the restaurant. At peak times we run nearly 100 pizzas (14") an hour through our oven. We start the gas-assisted oven around 10am, and start making pizzas at 4pm. We always keep 1-3 logs in the oven during service. When we get busy, our oven floor can't keep up. Pizzas will cook on top, but won't cook on the bottom as much as we'd like. We've found a way to work around it - we finish each pizza for ~10 seconds in the "hot spot" at the back of the oven - but it's a lot to keep up with, and it really slows us down.

    Has anyone else experienced this issue, or have any advice?

    Ideas currently on the table:
    • Lay an additional layer of brick for heat retention
    • Pull up the brick and supplement/replace the insulation
    • Start the oven earlier in the day
    • Start a wood fire in the middle of the oven early in the day, and push it back before service

    Equipment: Forno Bravo Modena 2G 120G
    Oven floor size: 48"x48"
    Oven floor material: 2 1/2" firebrick
    Floor insulation: 4"+ ceramic
    Temperature: 750-800 degrees F
    Heat source: modulated burner + wood

    Thank you for your help!

  • #2
    Two suggestions:

    - Reduce the opening size, both width and height. It will reduce the incomming air cooling effect. Use rough cut bricks and puzzle a little. Start with reducing only the width.

    - lift out the floor and insert 1/2-1" (as large/few as possible) steel plates to help spred the heat. Put the floor back. You already have very good insulation. If it is too fuzzy, add firebricks on top instread. It will lower your opening and door, but that is not nessecary a bad thing though.


    • #3
      As I see it, the real issue is that you're operating at or above the peak capacity for the oven. Fire bricks and refractory plates retain heat very well, but don't transfer that heat within the material very quickly. Most people find that you need to move/rotate the fire location to recharge the cooking surface(s) when actively running a series of pizzas through the oven. Cooking a pizza reduces the heat near the refractory surface significantly and it takes time for heat retained lower in the material to move up. Your insulation and cooking surface are good, unless it's really cold where your oven is located, the incoming airflow is not going to be as significant in cooling the cooking surface as putting loaded pizza skins down.

      ​​​I see two options for you. One: accept & let your customers know you have a "maximum occupancy" for pizza production. Most people will happily wait to get a "limited production" pizza, especially if you are upfront (and correct) about output timing during your peak customer order periods. Option two: consider installing a second oven to help meet your high demand for quality pizza.

      I suspect option one with a consistent rotation of fire/coals over cooking zones is your best option to keep up (and balance) product quality and customer satisfaction. Hope that helps.
      Mike Stansbury - The Traveling Loafer
      Roseburg, Oregon

      FB Forum: The Dragonfly Den build thread
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      • #4
        Originally posted by SableSprings View Post
        ....Most people find that you need to move/rotate the fire location to recharge the cooking surface(s) when actively running a series of pizzas through the oven. Cooking a pizza reduces the heat near the refractory surface significantly and it takes time for heat retained lower in the material to move up....
        That's great advice. I'm going to try shifting the fire from the one side to the other and see how that goes. Sorry to hijack the thread!
        My 42" build:
        My oven drawings: My oven drawings - Forno Bravo Forum: The Wood-Fired Oven Community


        • #5

          I've be at this for quite some time now in a profession setting so this is not theoretical advice.

          Since you are pretty vague on your initial firing process im going to address your bullet points first.
          • Lay an additional layer of brick for heat retention
            • This is not practical when you get to the oven opening in addition adjusting to the height difference will be an operational nightmare for your piliazzo.
          • Pull up the brick and supplement/replace the insulation
            • There is absolutely no way to do this. Not only does the oven design geometry not make it a workable possibility the actual construction of the oven would not allow for it.
          • Start the oven earlier in the day
            • The length of your heat up time is not the problem 6 hours is MORE than sufficient almost EXCESSIVE in my opinion. Unless your doing your heat up with JUST the burner. WHICH IF YOU ARE IS 90% OF YOUR PROBLEM
          • Start a wood fire in the middle of the oven early in the day, and push it back before service
            • If you are running your main heat source in the rear of the oven this is a big part of your problem with keeping the floor charged as well as cooking time and evenness. Your wood should always be either to the left or the right of your front opening
          Based on your last bullet Im going to assume you are doing your initial heat up with the burner these are called gas-assisted for a reason and in my opinion as well as others not sufficient for sole pizza cooking heat. The burner does not allow for good HEARTH contact of the heat yes your getting some top heat but it just does not make up for direct coal to brick contact. So here is my bullet list of suggestions
            • ​​​​​​​This will allow for a better floor charge in particular and an overall better oven charge AS WELL AS REDUCE YOUR HEAT UP TIME.
            • If you do no do this at all or are not familiar with the process please read up on it first as you could damage the oven.
            • After the burn off and your sure you have reached hearth temps (if you have temp probes what is their depth?) If you do not how are you determining if your hearth is completely charged? and are you confident it ACTUALLY IS completely charged?
            • I have found that allowing the oven to SOAK for about a half hour I have found to be INVALUABLE to oven performance. ESPICALLY when we are doing 50-60 pies and hour but also in over all performance its a much more smooth oven.
          • ​​​​​​​USE MORE WOOD THAN 1-3 LOGS
            • ​​​​​​​Again your mention of 1-3 logs tells me your heavily using the burner as your heat source. This is just not going to give you the hearth heat you need for your peak times and I believe you will be much happier with over all oven performance if you thing of the burner as an emergency back up rather than a primary (controllable heatsource)
            • If your oven is black at any time after the initial burn off of soot your oven is not being heated properly.
          • PLACMENT OF WOOD
            • ​​​​​​​When you are cooking with both gas AND wood the wood should be on the same side as the burner or you will get too much top heat and not enough will reach the floor because of the interruption of the convection cycle with duelling flames in the dome of the oven. In a pinch I have used wood on either side of my oven (no gas assist) and this works fine for a pinch but your top and side cooking times reduce drastically and if your hearth is not HOT and I mean HOT HOT the tops and sides will burn before the bottoms.​​​​​​
            • Your wood should neve be in the back of the oven for pizzas it completely interrupts the convection cycle and goes against the foundational design of the oven itself. These ovens (not just FB) but wood fired Pizza ovens specifically are the shape and ratio they are for the sole purpose of creating a convection cycle the retention time is just a benefit (because of the mass or lack of it)
          • MOVEMENT OF WOOD
            • ​​​​​​​Moving the wood IS ESSENTIAL to hearth recharge at the volume you are doing at that time.
            • You must do it gradually through out the day in order not to create a hot spot that is going to reduce your oven real estate for too long during service. When you move the fire the hearth bricks in that area are super heated. In order to cook there again you need to move the fire and allow that area to equalize a bit or you will burn the bottoms.
            • If you are gradually moving the fire through out the day by the time you get to your peak hours the floor will be better more evenly charged.
            • ​​​​​​​Rely less on the gas and more on the wood...I know its expensive and a PIA to train on but its sounds like you might need a bit of a primer on it as well so maybe you can make a training day out of it..yea right a day..more like the morning before service a few
            • That burner just cant produce the hearth heat like wood. Its is convenient but I believe, if you take my advice here or at least try it you will see that burner is truly just an assist there is no comparison to woods performance.
            • Also you don't make mention of it but the installation of a door (an INSULATED DOOR AT BEST) after evening service will drastically reduce your next day heat times.
            • If you are in a daily operation ( i didn't look up your profile) 6 hours for your initialheat up burn is..something is not right there again I think your using the burner to do the initial heat up OR the fire is just not big enough or hot enough for the oven.
            • So the heat up time and the lack of retention in peak times tells me that you are not fully charging the oven on its initial firing just bringing itp up tp operation temps and surviving off of the minimal residual the burner is creating. Which make work for regular service intervals but clearly not for peak times.
          I have NO idea what the heck is going on with the text in the last paragraph. lol

          Good luck


          • #6
            I agree totally with the post above..burn wood, lot's of it in the right places...
            Trying to learn what I can about flours, fermentation and flames...

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