Thermocouple and insulated door for oven

[Dieter01]

Hi,

I plan to install my oven on top of a concrete slap with a 2" Super-Isol board. I already own a datalogger that I use when roasting coffee so I was thinking of including one or two thermocouples when doing the installation. Would I get useful data if I place it with the sensor between the insulation and oven floor, in the middle of the oven? What type of probe have others used and how do you bring out the lead wire in a way that doesn't look to shabby??

I am also thinking about making an insulated door from leftover Super-Isol... I assume this has been done by someone already?

[WJW]

Re: Thermocouple and insulated door for oven

You will get useful data from mounting a TC beween brick and insulation as that will tell you when the brick is completely heat-saturated.

Others, including me, have made such doors. Too sleepy to help you out now, biut if you do a search you will find info.

Bill

[Spinal]

Re: Thermocouple and insulated door for oven

I'd would be interested too - in the UK finding digital thermocouples isn't easy... may have to order them from HK or China....

[nissanneill]

Re: Thermocouple and insulated door for oven

I installed 3 sensors in my oven, 1" below the cooking surface, 1" above the top of the dome and 1" from the full brick thickness to tell me how much saturation within the bricks, coupled them up with a switching unit and a digital display, all a waste of time and money!

Neill

[Spinal]

Re: Thermocouple and insulated door for oven

I installed 3 sensors in my oven, 1" below the cooking surface, 1" above the top of the dome and 1" from the full brick thickness to tell me how much saturation within the bricks, coupled them up with a switching unit and a digital display, all a waste of time and money!

Neill

Really? Why a waste?

Also, what is the switching unit you use?

[Faith In Virginia]

Re: Thermocouple and insulated door for oven

If you plan to do mostly pizza thermocouples are not necessary. With a bit of practice and experience with your oven you wont need that information to do great pizza's.

Now if you plan to do lots of bread and other baking thermocouples can help and be useful.

I do lots of bread and other slow cooking in my oven so knowing how much energy is stored gives me an idea of my target temperatures and how much I can load the oven. Slow roasting days after a firing is quite nice, especially in the summer because it keeps from heating up the kitchen in the house.

I built my oven for bread so I have 6 thermal couples with a digital switch.

High Accuracy Digital Thermometers

Then the switch
Multiprobe Switchbox For Handheld Thermocouple Thermometers

I went with the removable/portable that way when I'm not using the oven I can bring it all into the house for safe keeping.

Hope that helps

[mrchipster]

Re: Thermocouple and insulated door for oven

regarding the insulated oven door you may want to look at mine. somewhere in the middle at about post # 77.

http://www.fornobravo.com/forum/8/ch...a-16394-2.html

there are two things i will be changing on it and one that i wish i had done.

I will be changing the steel handles to wood. the steel gets much to hot. and i will be putting a decorative wood surface on the face of the door.

I wish I had not connected the back surface to the outer skin at so many locations. I believe i am getting to much heat transfer into the front skin. I believe I can cut away a number of rivets and attached inner stainless when i do the other modifications. I believe most of the heat transfer is coming from the contact of the inner stainless to the outer aluminum.

Chip

I regularly see temps in the high 200s after 5 or 6 days even after cooking bread and maybe a roast or casserole in between.

[Neil2]

Re: Thermocouple and insulated door for oven

When I first started, I used to take all kind of temperature measurements.

Now I just rely on experience based on how big a fire was burning for how long and how seasoned the wood is.

[Dieter01]

Re: Thermocouple and insulated door for oven

Thanks! I will go for 1 thermocouple below oven floor to learn when its saturated with heat. I will also buy one additional probe that I can move around a bit (perhaps lay on the floor to measure if its hot enough for pizza) and in addition fit through a hole in the door.

Thanks for the door link. I also came across these threads:
http://www.fornobravo.com/forum/f28/...oor-15671.html
http://www.fornobravo.com/forum/f8/u...oor-17634.html
http://www.fornobravo.com/forum/9/ke...or-3118-3.html
http://www.fornobravo.com/forum/f17/...ion-15049.html
Making a insulated wood fired oven door.

A plan is starting to form...

[nissanneill]

Re: Thermocouple and insulated door for oven

Spinal

Why a waste?

I was keen to build a very versatile oven and hang the expense, so I installed the thermocouples, purchased a switching device from the UK and used my digital multimeter for the readout. The temperatures that were given weren't accurate nor consistent. As Neil2 says, "Now I just rely on experience" which is great and I find much more consistent. I also use a laser digital thermometer to measure both the hearth and the dome but I mainly use the oven for pizzas and not much more at this stage. Now that is a waste!!!

Neill

[Spinal]

Re: Thermocouple and insulated door for oven

That was one worry I had/have - the accuracy of the readings...

I'll pop 2 TC's in or so for now... and see what happens. Cheaper to spend a pound or two now and put them in than regret it later

M.

[david s]

Re: Thermocouple and insulated door for oven

Thermocouples and their readiuts inevitably fail, you need to make their replacement easy when you install them. When cooking pizza you don't need a temp indicator to tell you the pizzas are cooking too slow and therefore the oven temp has dropped off. When baking and roasting a cheap oven thermometer placed inside the oven is a simple and accurate instrument, that doesn't require, drilling, wires, batteries or high cost. I've got a couple of thermocouples but don't use them in my oven any more. If you are keen to spend money get a laser thermo.

[jeeppiper]

Re: Thermocouple and insulated door for oven

I wrestled with the idea of using thermocouples....I am SO glad I did not use them. Instead, I simply bought a IR thermometer and take readings on walls and floor. You quickly get to know your oven and get a feel for the temperature inside just a few firings.

My opinion: don't waste your time with thermocouples. It only complicates your build and puts un-necessary holes in your oven. Buy a IR thermometer ($50) instead...you will have more data than you will know what to do with...just my humble opinion.

[WJW]

Re: Thermocouple and insulated door for oven

You know what they say about opinions...

I've got one too.

I did put thermocouples in my oven. Four of them to be precise. I am extremely happy I did so. I bake in mine, and I use it for retained heat cooking. If I were only using the oven for pizza, I would agree that they would be a waste of money. (BTW, mine cost forty bucks each). But having the thermocouples is very, very helpful for baking. They give me info that is impossible to get with an IR thermometer. (I have one of those too and agree that you need one.)

The thermocouples tell me exactly how saturated the masonry of my oven is because I have them embedded in different areas, and more importantly, at varying depths/distances from the interior of the oven.

Of the two in the hearth...one is between the firebrick and the insulation, so it is measuring the saturation of the brick at the farthest point from the hot oven interior. The other is mounted in one of the hearth firebricks which was drilled just over halfway through the brick going up toward the oven interior. So it is embedded in brick about an inch from the hot interior.

Of the two thermocouples in the roof arch, I did basically the same thing...one as far from the hot interior as possible where the insulation starts...one drilled into the brick an inch from the flames.

There is no doubt I could bake without them. I could simply build a very big fire in the oven and let it burn for four hours or so. I would know from experience that, after mopping out the oven and closing it up to allow it to equalize/cool for around two hours, my interior hotface brick would be around 600 and that it would cool down very slowly from that point due to the energy stored in the bricks. But there would be a lot of guesswork and I'd have significantly variable results from bake to bake. Not a good thing.

But with the thermocouples I know the exact temperature of the deepest levels of masonry. I usually try to time it so that I pull the fire out of the oven when the deeplest levels of masonry are around 625-650. In order to do that I start tapering off the wood when the deep layers get to around 590. By the time that happens, the interior of the oven has long since dropped from it's peak temp of 900 to 1000 degrees and now is dropping into the 700 range.

When the deep masonry layers get to around 625-650 I start raking the dying coals out and mopping out the oven. By the time I'm done doing that, the interior hotface bricks are around 550 degrees (after mopping/cooling/equalizing), and the deepest levels of masonry are still 650 degrees. I then close the door and let the interior come back up to around 590 or so before I put the loaves in.

I am then completely saturated and even as I put multiple batches of bread in, the oven cools very slowly from around 590 to about 500 over the course of four batches of bread. If I'm doing fewer batches, I don't let the deep masonry levels get above 600.

And, since every fire is different, I don't have to guess when I reach the correct point. By checking the thermocouple temps every thirty minutes or so, and regulating my wood input accordingly, I see my end point coming two hours before it happens. To a large extent I can make it happen exactly when I want it to.

All of that is critical if you have loaves of bread rising and you want to put them in at a certain time. And since different batches of bread (especially sourdough) rise at different rates (even when using the same recipe) the ability to control/predict when your oven will be at the right temp is HUGE.

But...if all you plan to do is cook pizza, all you need do is get the hot face up to 800 or better... keep it there for an hour or two (depending on how many pizzas you are cooking)...move the coals over...and you are good to go. No need for anything but a IR gun. Just depends what you plan to do.

As far as complexity or holes in the oven...that's a non-issue. For the hearth thermocouples, I simply put two drinking straws in the form for the stand before I poured the concrete. I pulled the straws out as the conrete began to set up. For the thermocouples in the roof vault it was easier. One TC I simply laid in place and set a small piece of brick on it to hold it still before I put the insulation blanket over it. The other one I drilled two inches into a roof brick, pushed the TC into the hole, and layed the blanket over it. Nothing to it.

Your mileage may vary on the usefulness, but complexity of instalation is not an issue.

Bill