Temperature ratings in wood-fired ovens

[Aussie Pete]

Re: Temperature ratings in wood-fired ovens

Hi all, this post hasn't been used for a while, but i think this is where this question belongs...input please..

is there a scale as to how the inside of the oven heat is maintained & dropped off, (bare with me....)

for example.. if an oven is a refractory cement mould 36" with a 19" x 11" door, and 3" fire brick floor and "x" amount of insulation on top of the dome (example only), is there a heat scale that it will hold temperature at, and a scale showing over time the drop off of heat. (Example...oven reaches 800F,... in half hour it is 770F, .....in 2 hours it is 640F, with no more wood added & door in place).
I hope i have explained that properly.

I'm guessing its just too hard to predict, with all the different types of ovens & materials.
Would such a scale be helpful in anyway, i'm thinking it might help to know when your good to go for baking breads, because you could get it to such a temperature, then check the scale and know that in say 3 hours, your good to start baking some breads. Am i over thinking the whole oven temperature idea too far, or would this "such scale" be useful. I'm also guessing that the more experienced oven owners here would know exactly when to cook anything, just in their head.

I suppose i'm a bit technical info brainiac...as in, i like to know all the facts and be in total control of what i'm doing. A bit anal you could say.
I'd also like to put thermocouples in my oven, but i'm a bit worried of their longetivity and their working life, i would hate to put them in the oven, only to have them fail 2 weeks later. I also would like to be able to place them in with the option to easily replace, can this be done without leaving gaping holes in my oven dome. The other reason, is i can acquire them easily and cheaply.

Sorry if i have missed this topic completely...."blame the novice guy"

[BurntFingers]

Re: Temperature ratings in wood-fired ovens

If the bricks are white. I throw a teaspoon of bench flour into the oven and if it turns black right away it is too hot. When it slowly turns brown in few minutes it is just right. That is the temperature I maintain.

[Pareshdv72]

Re: Temperature ratings in wood-fired ovens

Hi everybody,

Ok I am new to this and would like to know what temp should i maintain to make a pizza and not burn the cheese

[BurntFingers]

Re: Temperature ratings in wood-fired ovens

Ditto, we store some of our wood under the hearth. It gets nice and dry so it is easy to start. It doesn't get so hot to worry about ignition.

[RTflorida]

Re: Temperature ratings in wood-fired ovens

Paul - I have a 4" slab and 3 1/2" vermicrete insulating layer. The day after a pizza firing the underside is about the same as yours 115 - 125F. Initiallly, say in the 1st month of firings, it was more like 140 -150F. Once you drive out the moisture entirely and everything has curred the temp drops quite a bit. My storage area has always had doors on it and always seems hot and stuffy, but it isn't from excessive heat radiating from the hearth. I'm sure ceramic fiber board leaches less but I am happy that the underside is in the 125F range. I run my oven hot (hearth temp around 800 -825F for pizza) and the air temp in the storage area is typically around 100F for about 6 months of the year even if the oven has not been fired for weeks.

I wouldn't be the least bit concerned with what you are seeing.

RT

[Lburou]

Re: Temperature ratings in wood-fired ovens

Regarding Heat underneath the hearth: I have 5" of structural concrete and about the same of vermiculite/cement under the 2-1/2 firebrick oven floor. I measured the temp of under the hearth today and it was 127F the morning after a pizza cook. Is that normal? right now it's still open, but I want to put a door on it but i'm concerned about how hot it will be for storing wood, etc. Do I need to add insulation under there? any thoughts are greatly appreciated.

You don't need to worry about the safety of storing wood under there until about 450 F.

[Paul in Rockwall TX]

Re: Temperature ratings in wood-fired ovens

Regarding Heat underneath the hearth: I have 5" of structural concrete and about the same of vermiculite/cement under the 2-1/2 firebrick oven floor. I measured the temp of under the hearth today and it was 127F the morning after a pizza cook. Is that normal? right now it's still open, but I want to put a door on it but i'm concerned about how hot it will be for storing wood, etc. Do I need to add insulation under there? any thoughts are greatly appreciated.

[joe bloggs]

Re: Temperature ratings in wood-fired ovens

No, I doubt they will spoil the broth - I didn't mean they would all be going at it at the same time! I was going to try to make the thermocouples removable, either by using proper stainless steel probes with thermowells, or by using copper or stainless steel tubes to slide the wires down. Do you know if this works?
Thanks for all the help!
joe

[dmun]

Re: Temperature ratings in wood-fired ovens

the oven I am building will be used by a large number of cooks (at least 20)

Will they spoil the broth?

Your oven will rarely get above 1000 degrees f., and less on the inside of the brick. I think the only real reason to have thermocouples is to measure the saturation of the heat into the dome, so having two at different depths should be good. You may also want to consider planting a reserve pair while you're doing it, as they have a tendency to fail.

[joe bloggs]

Re: Temperature ratings in wood-fired ovens

I have read elsewhere on the forum that most people who install thermocouples tend not to use them after a few months when they have gotten to know their oven's characteristics. However, I am in a unique situation as the oven I am building will be used by a large number of cooks (at least 20) and I will have to have some way to tell them what temps/techniques they need for a particular dish or cooking style and have some way for them to verify that they are doing things right without any experienced eye to tell them if the dome is white enough or the flour burns fast enough. I hope this explains why I would like to install thermocouples. I want to put in two close together about half way up the dome on one side, one measuring the inside of the brick and one the outside. Will this work for the above mentioned situation or does someone have a better suggestion? I have decided to go with thermocouples that are rated to 800? Celsius or 1472? Fahrenheit. Will this be high enough?
thanks, joe

[david s]

Re: Temperature ratings in wood-fired ovens

After you have fired your oven many times you won't rely so much on temp gauges, because it will do the same thing. Most take 1.5 Hrs for heat to soak the bricks and around 1Hr for the inside to go white. For bread or roasts a cheap oven thermometer that goes inside the oven is quite accurate and measures the temp where you want it.

[david s]

Re: Temperature ratings in wood-fired ovens

Take some semolina flour and throw it onto the floor where you want to cook. 3secs between casting the flour and it turning black is correct for pizza. 2 secs too hot 4secs too cold. If your oven floor is too hot try placing the pizza nearer the entry where it will be cooler.

[KEmerson]

Re: Temperature ratings in wood-fired ovens

Joe: From my experience so far (finished the oven and began baking only last October) when I get the oven up to pizza temperature, that oven will still be at least 400? F the next day, easily in the 200? range 36 hours later. I've had it at about 150? 48 hours later. It comes down to what has been gospel on this forum: You cannot over insulate. You can over kill but you will only benefit from it. So, for bread I simply get the oven up to about the 900? - 1,000? range, rake out the coals, maybe - or maybe not - put the door on and let it cool down gradually to bread temperature (500?). Replacing the door or not is a matter of regulating the rate at which the oven cools down. A well insulated oven shouldn't lose so much heat after getting that hot that you have to worry about heat loss for bread. But, the adding of several loaves will drop the temp. a bit so that if you want to do a second bake after removing everything from the oven's first bake, you might have to build a new fire. But if the first fire took 1 -2 hours to get up to the 900? range, the second fire might only take a half hour. And if the ambient temperature (outside air) is a hot summer day, even a first firing will only take an hour.
I'd like to know for myself, though, if the temperature drop rate is faster from, say, 1,000? to 500? than it is from 500? to 0?. Or does the temperature drop equally all along the way?

As for how high the thermometer should be rated, I'd say above the 800 as you'll be wanting the oven to hit at least 900? or 1,000?. So go for that higher one of the two you mentioned. (I'm still trying to learn the throw some flour on the flame trick. Have you come across that one yet? If nothing else, it impresses people, which is part of what we're here for.)

Now that you've read what I have to offer, look back up at my name and you'll see I'm still an apprentice. I'm not sure how we move along that scale, but "apprentice" should signal that wiser heads may be lurking.

[joe bloggs]

Re: Temperature ratings in wood-fired ovens

Thanks for all the replies. I want the outside temp of the bricks i.e. just inside the insulation to measure the heat soak through the bricks. I am told this is useful when baking bread and doing other long term cooking, where you need to be sure you have fired your oven long enough that it will stay hot long enough. Other people may know more or have experience. So how high do my thermometers need to be rated? 800?C is 1472?F. Is that high enough?
joe

[KEmerson]

Re: Temperature ratings in wood-fired ovens

Joe: Why do you want the outside temperature?
David: I doubt the oven ever gets to 1,300? F, but what does it mean when my thermometer reads either HI or, sometimes, it reads only about 100? when it's well into the 900?+ range? For instance when I point at the burning wood it can read 100? but the hearth just in front of the wood, or the walls nearby will read 900? or so. (My thermometer is a Thermo Tech 1382. Its range is from a low of -4? to a high of 1382?.)