32" build in Calgary, AB - pompeii neapolitan

[IH123]

I today started curing the oven with electrical heater (without any dome insulation) to dry the bricks out before winter freezing as if there is lots of moisture in it and temperatures gets lower than 4c it could freeze and cause cracks. I tried today a heater at 750 watts setting , it has thermometer so I set it to shutoff when air temperature reaches about 43C. I plan tomorrow to increase that to about 60C (or whatever its allowed to by the heater as long as its <60C). I will run it all day long while I am at home and turn it off at night. no tarp or covers at night as its still not below freezing for next 14 days (forecast) so to let anything evaporate and not get trapped in a tarp at night.

[IH123]

I am left with 22 unused bricks from the 188. That's I used 166 bricks. however I wasted by wrong cuts few of them, I estimate less than 10. therefore the actual exact number of 9"x4.5"x2.625" bricks used was 156. for mortar, I used 3, yes, x3 50lbs +x1 25lbs of Thermobond 915 refractory mortar, which is 175 lbs total. I would estimate the waste in mortar was about 25lbs so total 150lbs are in the oven. the bricks produced >= 4 large pails of grog( each would have about >15 litres by volume or >60 litres total, which is equivalent to >=115kg, which is equivalent to >=35 full bricks, which is >22% waste. with one full brick weight is 3.3kg, the oven mass wold be about :
156x3.3kg(bricks)+68 kg cured mortar- brick cut grog waste of 22%x156x3.3kg=~470kg

I have halted warming up the oven as the weather cooled down during a storm and I will continue warming/drying after it finishes as temp will swing from +10c to +21c (during the day) which makes warming the oven with 750 watts more productive.

and now I am scrambling to design and build a heavy duty snow shelter for the oven as the dome is pure unprotected brick.

[IH123]

I today cut to shape and descaled the A36 carbon steel door(3/16" thick), I drilled for handles and thermometer . I will season it with 500,000BTU propane torch and grape seed oil to prevent rust. I will not paint as inside face wont work well with paint. I will use 1/4" stainless steel threaded rod with nuts to secure a wooden handle(two, one one each side) . yet to use flapping disc to smooth the surface and clean it with alcohol before applying the grape seed oil. pictures of assembly before smoothing and seasoning (pending):

[david s]

A heavy carbon steel panel door is very conductive and has a lot of thermal mass, so although it is durable it is a less than ideal material, because especially if uninsulated it will draw valuable heat from the oven. See how it performs, but you may want to consider attaching an insulating panel to the inside face to improve performance.

[IH123]

A heavy carbon steel panel door is very conductive and has a lot of thermal mass, so although it is durable it is a less than ideal material, because especially if uninsulated it will draw valuable heat from the oven. See how it performs, but you may want to consider attaching an insulating panel to the inside face to improve performance.

you are right. I however plan to create a wood pan with same shape as the steel part, which have around 1" egde and use fibre glass gasket to hold the steel and wood tight together touching on gasket. will drill tiny holes in the wood container to vent. this will use air gap insulation between the steel and the outside wood. this will be made when creating the wood handles.

[IH123]

here is the design. the stainless steel threaded rod will penetrate across all layers and the wooden handles (not shown) will compress further the wood face to the steel face compressing the fiber glass gasket:

[Giovanni Rossi]

I've been delayed building v2.0 of my insulated wood insert. I get days of retained heat cooking with just my steel door, but I wanted to experiment to see how far I could extend that.

v1.0 was made using maple encased Foamglas. The lesson I learned was the need to respect the flameless spontaneous ignition temperature of hardwood (~450^oF). The inside face of the insert was destroyed after two uses.

With v2.0 I'll use my steel door until the oven temp drops below that. Even with that technique, the hardwood will char and be damaged over time. Your design will allow easy replacement of the wood panel once that happens.

[IH123]

I am actually thinking that if I use a thin steel sheet instead of wood , having it bent inside to form a seam of a pan all around, then fibre glass gasket between inner thicker 3/16 plate and outer thin steel pan would probably still provide very good insulation even with bolting (not welding). this is because the cross area remains to transfer heat by direct contact is very small (4x1/4" diameter circle area) . air inside is extremely low density so even if its spanning the entire volume , the heat transfer through air will be very small (think about it like if air is compressed into liquid, wont be even a drop from that volume of 10x17"). the decision of what material to use will be made based on simplicity and cost, as I feel not much difference of the material insulation value when its insulated with a gasket. At the end, the door it self is not pressure locked so no matter how far someone go on insulating the door, the heat will simply push the door open and run out.