Karangi Dude's 48inch Oven

[Bert]

Re: Karangi Dude's 48inch Oven

See your point re the floor, I guess it always good to over engineer!

Hows your thermal coupling going? I expect its not cheap but great to have a good accurate and easily obtained thermal reading.

Bert

[Karangi Dude]

Re: Karangi Dude's 48inch Oven

Bert, these things are over engineered by a long way.
It is surprising to see how well they do hold there temperature though.
Once you put the door on it takes a few hours and everything starts to equalize all the 6 thermo couples read about the same and they all read the same as it cools down, a big difference to when it is heating up.
Yes the thermo couplings are expensive along with the digital display and the hand held laser thermometer that takes an extra thermo coupling, it will be good though and good for the forum I will be posting results as I get them.

[Karangi Dude]

Re: Karangi Dude's 48inch Oven

Hey All,
The planned monitoring of my thermo couplings was interrupted when I was called away for 1.5hrs just after I lit the fire so I will have to do it again at another time. I do have some results but I did not take any laser readings to compare with.
The most significant reading was the difference from inside the fire bricks to the outside and how long they take to saturate.

See Diagram Below for Placement of Thermo Couples

3.00pm
Lit fire all readings @ 17 / 20c

4.30pm
1. 10mm under floor 537c
2. 65mm under floor 56c
3. 10mm iside wall 282c
4. 10mm outside wall 244c
5. Air temp 547c
6. Under insulation 25c

6.00pm
1. 10mm under floor 623c
2. 65mm under floor 147c
3. 10mm iside wall 436c
4. 10mm outside wall 265c
5. Air temp 352c Note temp dropped as I had moved the fire to side
6. Under insulation 40c

8.00pm
Let fire die down left door off

9.00pm
1. 10mm under floor 302c
2. 65mm under floor 240c
3. 10mm iside wall 290c
4. 10mm outside wall 305c
5. Air temp 294c
6. Under insulation 66c
Note at this stage the oven was starting to equalise.

These readings may not mean a lot everybody, but it does show that even when the carbon starts to burn off, inside the bricks the temps are a lot lower than expected.

[Bert]

Re: Karangi Dude's 48inch Oven

G'Day Doug.

This is interesting from my perspective...the fact that the temp at 65mm below is quite high and on the outside of your insulation (from memory you used 75mm insulation refractory bricks?) is much lower. What concerns me for my build is if I use those 300 x 300 x 50 floor tiles + the insulation bricks my slab temp will be + 70 degrees Celsius. Given the proximity to the neighbours I am paranoid about excess heat. Good food for thought! Thanks for the data!

Bert

[Karangi Dude]

Re: Karangi Dude's 48inch Oven

Hey Bert,
I think I have mislead you the temp at 65mm is inside the floor brick.
Did you look at the diagram referring to the placement of the thermo couples.
The insulation fire brick works extremely well with the bottom of the insulation brick at only 66c, that is not very hot when there is a 240c fire brick sitting on top.
Remember boiling point is 100c.

[Bert]

Re: Karangi Dude's 48inch Oven

Ooops! Didnt see the diagram. Take you point re overall temps considering the overall heat within the oven.


Bert

[Alter ego]

Re: Karangi Dude's 48inch Oven

Doug,

It is interesting to see these tepm readings.

When I use my oven I always try to burn for at leats 3hrs so that I fully soak the bricks, this way it retains the heat much better and I can use it for 2 days after. If I only burn for 1 to 1.5hr before cooking pizza I find that the oven cools off too quickly.

If you are able to, please let us know a few readings about the rate the oven cools down.

[Karangi Dude]

Re: Karangi Dude's 48inch Oven

Hey Paul,
Good to here from you.
I agree wholeheartedly that the oven needs time to heat up and saturate, I always start with a small fire and slowly build up from there.
I will be doing a lot more tests both heating and cooling.
Paul, I did notice though that after you put the door on, the oven equalises completely the air temp is the same as the rest of the oven and the thermo couples all read within 5c of each other except the one under the insulation. I am not sure how long it takes but the next morning after I have had a fire and placed the door on the night before that this has happened. (I don't take the fire out I just spread out the coals and ashes over the floor and put the door on) some times 8 to 10hrs later the coals are still glowing a little when I empty them out to bake bread.
So for all the people who put a thermometer probe through their door to measure the air temp this will actually be the equalised oven temp given the door is placed on and that the dome and the door are satisfactorily insulated.

[Lburou]

Interesting data Doug!

Doug, how many times have you fired the oven since your curing fire(s)? Do you think the oven is completely cured?

Celebrating the milestone with you and laud your success Doug

[Karangi Dude]

Re: Karangi Dude's 48inch Oven

Hey Lee,
That was my third firing after the initial long curing, I think the oven is most likey cured and do not think there is any moisture under the floor with the low temp showing under the insulation bricks.
Lee my oven was completly build under cover so it was not effected by rain at all and there was a fair gap in time from when I closed up the dome to when I first started to cure it. Tests over the next few fires will tell I suppose.

[Karangi Dude]

Re: Karangi Dude's 48inch Oven

Hey All,
What to do with all these tools?
I was just noticing all the tools that I use for the oven and I probably need a couple of others as well, like something to lift those 2 foot logs that I sometimes use. Here are a few, 2 Brushes one brass one soft, 2 Shovels one for ash one for moving the fire around, 2 Scrapers one wide one narrow and the list goes on.

[Karangi Dude]

Re: Karangi Dude's 48inch Oven

Hey All,
I have been using the retained heat in my oven for lots of cooking tests.
First I must say that with a 48" oven it does take a good fire to get it nice and hot and time to get it saturated. What I have noticed is that if I only use 1' blocks it takes a lot longer to to get up to temp and maintain that temp. So I have started using a 2' log about 6" dia when I move the fire to the side and when this log gets going I reach the temp I wan't and it maintains the temp for a long time with just that one log.
Now that I know that I am reaching the required temps and saturation by the many thermo couplings that I have in the oven I have been working on the retained heat.
After cooking Pizza on a Sat night I wait a good while after spreading out the remaing coals before I place the door on. Sun morning at say 10am the oven is way to hot for baking bread even after I have cleaned out the ashes and left the door off for a couple of hours. So I have been cooking a roast for lunch and then baking bread in the late afternoon for eg. last weekend Sat night cooked Souvalaki, Sun morning cooked Roast Pork and Veg, Sun Afternoon cooked Crusty Bread Rolls, Monday let oven rest with door on (no cooking) Tue morning put in slow cook Ossobucco whilst at work, Tue night made Beef Jerky over night, Wed morning Drying Banannas and Tomatoes whilst at work.
I have taken a lot of temps from the Digital Display but at this stage not really logged the cool down, I will get to that soon and post for your info.

[Jayson]

Re: Karangi Dude's 48inch Oven

Food looks fantastic Doug! Great variety.

[Karangi Dude]

Re: Karangi Dude's 48inch Oven

Thanks Jayson,
I am still in my testing stage, there is a lot more dishes I would like to try.
With the drying of the banannas and tomatoes I think because there is no air movement it may take a bit longer than with the dehydrator. I need more time to test these things (tomato season is a fair way off yet) I like to use the retained heat to cook something it's just a lot of fun I suppose and it costs nothing yeh!!!!

[Bert]

Re: Karangi Dude's 48inch Oven

Your making me hungry Doug!

You should add a shoulder of lamb or beef to your list.

Jamie Oliver cooked a lamb shoulder on his WFO and it looked awesome.

I am also waiting on the suckling pig dish!

Have you used the WFO as a tandoor yet? i have read that you can make good naan in them.

Keep up the ggod work!

Bert