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Post by woodywun on Jun 19, 2020 19:37:47 GMT
Hello,
I'm building a cast dome oven and having got the base layer and an insulating layer of Vermiculite concrete complete on my stand, I'm looking to cast the dome with a homebrew mix. I want to see if I can incorporate a probe thermometer.
I could build this into the cast dome as I go; I could let the dome cure and drill a hole through to accommodate the probe; I could build it into the door or I could just go for a free-standing one and peek in now and again.
Any thoughts, ideas or experience on this?
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Post by oblertone on Jun 20, 2020 7:22:46 GMT
Door fit is easiest and doesn't impact on the integrity of your dome; however, they are of no use when cooking pizza but can be useful when doing extended cooking i.e. With the door on.
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Post by woodywun on Jun 20, 2020 10:28:40 GMT
Thanks for your reply oblertone. I'll build the thermometer into my door design. I'm hoping to use my oven for some extended cooking, including bread so knowing the temperature will be important to know. So for pizza, heading for 250-260 Celsius, just using a lift-in thermometer will do the trick?
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Post by webbm00 on Jun 20, 2020 20:49:41 GMT
I built a lot of K type thermocouoples into my design from www.thermosensedirect.com. You can get digital displays for these thermocouples on-line if you don't want to go down the home made interface route
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Post by downunderdave on Jun 20, 2020 20:51:53 GMT
Hello, I'm building a cast dome oven and having got the base layer and an insulating layer of Vermiculite concrete complete on my stand, I'm looking to cast the dome with a homebrew mix. I want to see if I can incorporate a probe thermometer. I could build this into the cast dome as I go; I could let the dome cure and drill a hole through to accommodate the probe; I could build it into the door or I could just go for a free-standing one and peek in now and again. Any thoughts, ideas or experience on this? I found drilling a hole through the oven from the outer shell through the insulation and into the inner dome after the whole oven is completed is far easier than building around a thermometer probe. You do need to select the correct length of probe though. I also encase the probe in a stainless steel sleeve to protect it. I found a thermometer probe attached to the door gave a much lower reading than a cheap air temperature oven thermometer placed in the centre of the oven, but this may just be my oven design. It is also subject to damage when frequently moving the door. After plenty of oven use temperature gauges are not required. For most of my baking and roasting I simply fire the oven for one hour, allow the flame to die, then pop in the roast or bread. After one hour the oven is not saturated with heat, but is sufficient for roasting of baking.The soot is usually burnt off at the top but not the sides of the oven. I use this an indication that it's ready too.
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Post by woodywun on Jun 22, 2020 8:32:59 GMT
Many thanks for your posts. I'm checking out the thermocouple idea and looking into 'sleeving' a probe through the cast dome. Thanks for the tip on the relative ease of drilling into the dome. Interesting what you say about the potential damage to the thermometer on the door and possibly a miss-reading.
I'm sure I'll relax back with regards temperatures when I've learnt how to manage my oven. It's a new venture for me.
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Post by woodywun on Jun 22, 2020 8:34:36 GMT
...just another quick thought: So no problems witht the steel sleeve expanding and cracking the casting?
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Post by downunderdave on Jun 22, 2020 21:49:15 GMT
No, not if you make it a slightly loose fit.
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Post by james9 on Jun 25, 2020 15:15:53 GMT
One thing to bear in mind and what nobody tells you is understanding the oven temperature is an art not a science and will be bespoke to your oven, the temperatures vary massively within the dome. With dry wood I could get the top of the dome up to 500c within 5 minutes and over 700c within 30-60 mins basically due to the flame. But this doesn’t tell you how much energy has been absorbed by the bricks (thermal mass) which is important because as soon as the fire dies down the temperature rapidly falls if it’s a quick burn. The dome roof goes white/grey around 700c which is a useful visual indicator.
I put two thermocouples between the base insulation and the brick floor so when they read 120-200c which takes 1-2 hours of burning I know the floor has absorbed a lot of energy. The biggest issue with thermocouples is the wire cables rusting from moisture/rain so they’re more sensible for completely covered ovens. Laser thermometers are useful though they’re just giving the spot temperature.
Some people use an oven probe drilled through the door, that will give an indicative temperature and in time you’ll interpret what that means for your oven. The entrance temp varies a lot and is much lower near the floor so the height of the oven probe will have an impact.
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Post by downunderdave on Jun 26, 2020 0:28:31 GMT
"The dome roof goes white/grey around 700c which is a useful visual indicator." I think you have your IR thermometer set on F. There is a button on it that toggles between C and F. The carbon starts to burn off at around 300C.
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