Infrered thermometer give good indication?

[prairiemountainmasonry]

HEy folks, I just built an oven for a customer. We opted not for implanting any temp probes/thermometers directly in the oven.. It is mainly for pizzas so exact temps aren't as crucial as for breads.. That being said we figured that having an infrared thermometer gun might be handy to get to learn the stove, and to check temps throughout the day. Can they give an accurate reading? I assume that the laser would tell you the actual brick temp, wherever you aim it, and that may be much higher than the air temp. would a small thermometer that is placed within the oven off the floor be more accurate? Thanks for your advice.

MAtthew

[texassourdough]

Re: Infrered thermometer give good indication?

Hi Matthew!

The following my opinions only. I suspect others will provide alternative views!

Thermocouples are more interesting than necessary. When you are learning your oven they are useful in knowing how heat loaded your oven is but after using the oven for a while for bread you learn your oven and its characteristics, how long it needs to be fired, etc.

Some people put thermometers in the door. My Casa came with one in the door - and I consider it useless. Ditto conventional oven thermometers. Air temp is pretty meaningless. Has no use for pizza and is a lousy indication of the oven condition with the possible exception of cooking roasts etc in dutch ovens and even then the oven is so forgiving that it is no big deal.

The Infrared Thermometer is IMO quite useful for learning both oven control for pizza and for baking. For pizza the hearth temp is the critical factor. And you will want hearth temps between about 700 F and 800 F. Most of us seem to prefer 750 or 800. Much over 800 gets to be a problem. The dome temp is meaningless for you should have flames radiating heat down.

For baking (no fire, clean oven) the hearth will typically be about 20 to 30 degrees cooler than the dome for a loaded oven. And you typically focus on the hearth.

Good Luck!
Jay

[prairiemountainmasonry]

Re: Infrered thermometer give good indication?

For the price that they are, I think We'll just get one that can go up higher than 700.. I think it will be good to help the learning curve in the first few firing. I agree that for pizzas, its forgiving as long as the cook is attentive.. Obviously time and experience will be the most important factors, but if there are several operators, residual heat from a long firing the night before, having some sort of gauge could be very handy.. Kinda fun shooting a laser into the dome as well... IF there are recommended brands or sources, that would be appreciated as well thanks.. I am a MAson who builds masonry heaters as well, so I will have other uses for this thermometer.

[nissanneill]

Re: Infrered thermometer give good indication?

prairiemountainmasonry,
I built 3 thermocouples into my dome and hearth and as texassourdough says, they are pretty much useless!
You will be best as I and many other no doubt have done, purchased a good laser pointed thermometer, mine max's out at 500˚C which coos a pizza in 60 seconds, so that's pretty much the range you should aim for.
Experience will eliminate the need for "accurate temperature control" as the lasers are reasonably accurate BUT the distance that you put the beam to will affect their accuracy. Also, whilst you are checking a half dozen temperatures throughout the oven, eg hearth in various locations, lower dome, and the top, the oven temp will drop a little.
Trial and error over a reasonable timeline is your best guide to cooking times, also governed by the delightful aromas that evolve. I'm looking forward to spicy buns in a couple of weeks with the grand kids.

Cheers.

Neill

[david s]

Re: Infrered thermometer give good indication?

The trouble with the IR thermometers is that they read the surface temp. this can often be misleading, especially for the first hour because the temp deeper in the refractory will be considerably lower until it has been fired for a long time.

[prairiemountainmasonry]

Re: Infrered thermometer give good indication?

Thats sort of what I was getting at.. It makes a lot of sense that you might get a high surface temp (700) , but if that hasn't penetrated to the core, it'll likely drop.. I also understand that after a few firing it'll be easy to determine whether enough time has passed for the heat to penetrate, and that experience will be the ultimate tool to use to pump out great pizzas. It seems that of all the temps to read, the hearth temp will give you the best idea, because if the hearth is up to a good temp, then logically the dome has also gotten to an even higher temp. Thanks for advice.

MAtthew

[texassourdough]

Re: Infrered thermometer give good indication?

Simple rules of thumb...

Regular pizza oven - about 45 min to an hour to clear (mainly a fxn of fire size from my experience.) (I built a really hot fire yesterday and cleared my oven in half an hour. It was almost scary!)
- about an hour and a half to 2 and a half hoursto heat load for baking (or after a long pizza session.

Barrel Vault - about 2 to 4 hours to clear
- up to six hours to heat load for baking.

In all of this if you don't heat load enough the refractory will suck heat from the oven and for pizza the hearth will tend to drop in temp as you make pies, (that actually happens anyway but it is exacerbated by cool refractory) and for bread/baking the temp drops way fast in the oven and the temp won't rebound properly after you load to properly bake the bread.

One other detail you may have missed about temp. The easiest and cheapest way to know the hearth is at pizza temp is to throw a small handful (a half teaspoon or so) of semolina (or four but not corn meal) on the hearth and begin counting. The semolina should suddenly turn black at about three seconds (or a slow count of three - one thousand one, one thousand two, one thousand three). If it is two seconds or less it is too hot and if it is four it is a bit cool and five is too cool

As David said they only tell you the surface but for pizza it is primarily the surface heat that cooks simply not enough time for much heat to migrate from down deep to the surface... Also, with pizza the fire helps keep recharging the surface so you can to good pizzas without worrying much about the "deep" refractory. Bread/baking is a different ballgame. Starting with partially loaded refractory is guaranteed to cause headaches and inconsistent results. Roasts and such are far more forgiving for they are not as temperature sensitive.

[david s]

Re: Infrered thermometer give good indication?

We often do roasts in a partially heat soaked oven to save time waiting for the temp to drop. We fire for exactly one hour from light up, let the flames die, then place the roast and seal the door. Every oven is different and you have to fire it lots to get to know it.

[texassourdough]

Re: Infrered thermometer give good indication?

Good comment, David! Partially loaded ovens do have a place! But you need to know yours and experience is the ultimate guide!

[WJW]

Re: Infrered thermometer give good indication?

A bit of a contrarian view on a couple of points.

I love having thermocouples imbedded in the masonry. The data they provide is meaningless for cooking pizza, but I find it to be extremely valuable for doing large bakes of bread (say 20-30 loaves). The data provided tells me exactly when I'm heat loaded to the degree I'm shooting for.

Could I bake bread without the thermocouples? Obviously. But my results in large bakes would not be as consistient IMO. When I'm baking a bunch of bread I want the deepest portions of my masonry (in the ceiling arch) to be about 620 or so...and I want the surface temps to be about 580. For the hearth, I want the deep portions of the masonry to be about 600, and I want the hearth surface temp at 560. That temp mix is the ideal for my oven and allows me to bake up to forty-five, 1.5 pound loaves of bread on a single firing...in an oven with zero cladding. There is no way I can achieve those exact numbers without monitering. And no other way for me to know exactly when I'm where I want to be. I could simply build a huge fire and let it go a long time...but I'm likely to be over saturated and burn bread on the first bake.

The other thing, I have to take issue with Jay's numbers on clearing time (or loading time) for various ovens. The shape of the oven (pomeii vs. barrel vault) has no impact on how long it takes to clear...or saturate. The issue is thermal mass. If the oven has lots of mass, it takes a long time to clear and/or saturate. I can easily heat my oven to clearing (and pizza cooking temps) withiin an hour to an hour and fifteen minutes.

The pic below is from last weekend...that was a last minute pizza cook. The fire was lit at ten to seven. This pic was taken at 8:15-8:20.



For me..bottom line on thermocouples depends what your plans for your oven are. If baking bread they are worth doing in my opinion. If it's just pizza, probably not.

Bill