Finally Started in Southbury Ct.

[Aegis]

First, let me say I am an electrical engineer by day. That will probably answer most peoples questions why I do things! LOL As for the particular question, why thermocouples? I am not good at winging it so to speak. Others like yourself and my wife are really good at it. My wife doesn't understand why I use a level, she just puts up the shelf, eyeballs it a voila! Perfectly level! (I know it is level, cause when she isn't around I pull out that dastardly tool and check.. Me on the other hand, I need empirical data to support what I am trying to accomplish. I am trying to learn how much wood burning it will take to saturate the entire thermal mass. Then I want to record the cool down over days so I can have a cooking strategy that will work. Even if that means a re-fire (which I have to monitor with those darn thermocouples) I am hoping once I learn how my oven is working, then the thermocouples will be for showing guests how dam hot the oven is and not to stick their head inside! I am hoping to bake at least one batch of bread after a pizza party. Maybe 15 loaves or so... is that realistic with a straight pompeii designed oven? Or should I be looking at more thermal mass? Thanks in advance for any and all help!

[DimTex]

I work with a lot of engineers so I get it. Batch of 15 loaves? That is a lot of dough. For my 36 inch Pompeii in Texas that I built with my son last year the first thing is to learn how to build the right fire. I must admit I started too timidly putting in 2-4 logs and then waiting forever never getting hot enough. then I watched a YouTube from the Forno Bravo site and I realized I was not using enough wood. Now I have a system using six logs and kindling.

Anyway once you build the fire, I found it takes more than an hour to get the ceiling of the oven white which means the fire is hot enough to burn off the soot created during the low temperature start up. Problem is I think once the oven reaches 900+ degrees in my mind the consumption rate of the logs in the oven accelerates. You don't want to feed more wood because it takes up floor space that you need for cooking.

Now you have your oven hot, white ceiling hot. You push the coals to the side, let the center floor settle (cool down slightly) and you start cooking. I think most of the charts have shown the drop off in temperatures happens fairly fast. First hour really hot, second hour maybe 30 percent lower and by the third hour another maybe a couple of hundred degrees cooler, not much. So maybe at the start of the second hour after you brush the coals to the sides you could maybe start baking. I say this because in baking a steady temp is really important. With a pie you can pull it in and out to your hearts delight, with bread you have not a clue what is going on inside. I have charred rolls with almost dough at the core. By this time, if you have a party your guests will wonder whether you will join them!

You mention days, my experience is that by about hour 5 after the burn the oven floor and walls may be hot but not bread baking hot. I have just had a metal door constructed so maybe I will be able to conserve more heat, but for now I would say I do pizza in the first hour or so after the burn, then I do rolls and then breads....

Hope this helps

[Aegis]

Thanks for the info, it is a huge help! I am going to build a 40" oven and hoping to make pizzas the first night and then bake bread the next morning. It looks like I need to add thermal mass to the standard Pompeii design. I am prepared to heavily insulate it. 4" foamglas under the hearth, 3" thermal blanket on the dome with loose vermiculite on top of the dome. Now I just need to decide how much thermal mass and where to add it. I was thinking the hearth bricks could either be a double layer or just layed on edge. Then the mass increase around the dome???? add some refactory cement??? anyone with suggestions???
Thanks in advance

[Pisani]

Hey John,
What did you do for the floor insulation in the floor?
Tony

[Aegis]

Hi Tony, I have 4" of foamglas for under the hearth. Is that the insulation you are asking about? Basically I have 42" sono tubes for footings, under the slab is 10" of 3/4 stone compacted with a sheet of plastic over it, rebar and then 6" of poured concrete. The blocks were dry stacked and filled with rebar and concrete, Then the top was cement board, rebar and 4" of concrete. That is as far as I have gotten. Next steps are 4" foamglas, hearth bricks and dome.
Come over anytime and shovel out the oven and you can see it! LOL