Oven Accuracy


 

JayHeyl

TVWBB Pro
ThermoWorks is always sending me email. That doesn't in any way distinguish them from other merchants. My email box is loaded every day with efforts to sell me something. Why I need to hear from Park Seed every single day is beyond me. But I digress... What does distinguish ThermoWorks is that they almost always include something actually useful and informative with their sales pitches.

The other day they sent out one about the ChefAlarm, which is $7 off right now, and included a link to an article about using it to test your oven's accuracy. I did this yesterday and discovered a number of interesting things.

The most important thing, which I already knew but re-verified, is that I have to come at the oven setting from above, not from below. It's an old analog oven with a simple dial. If you start from Off and turn directly to the temp you want you'll end up with an average temp about 40F below what you want. If you first turn the dial to max and then come back to the temp you want it's almost dead on accurate. You wouldn't believe the number of meals that took way longer than expected before I discovered this.

The second thing I learned, much to my surprise, was that once fully heated and through a couple cycles the oven is fairly accurate. If the dial is set as mentioned above it will maintain the set temp +/-20F. That's really not bad.

There were a couple catches. The thermocouple apparently takes a long time to react to large changes. This means incredibly wide initial swings in temp. With the oven cold I set it to 325F. The temp went all the way to 418F before the burner turned off. (It's a gas oven.) It then dropped steadily back to 280F before coming on again. It continued with declining oscillations through a couple more cycles, eventually maintaining +/-20F of the set temp. The other catch was that it takes almost an hour for the oven to heat to the point that it's fairly stable. It's not insulated very well and it takes a while for all that metal to reach a stable temperature.

It seems odd that I can usually maintain steadier temps in the WSM than I am able to in the gas oven.

Anyway, the point of this wasn't to inform everyone of the peculiarities of my oven, but to illustrate what you might learn about your oven by going through this exercise. The ChefAlarm's recording of min/max temp makes this a lot easier since you aren't forced to watch the thermometer the whole time. You could use any temperature unit that can do air temp readings at the desired temperatures, you just might have to pay a little closer attention to determine the range of temperature swings. This ended up taking about three hours start to finish, but it needn't take that long and it's not like I was anxiously watching the oven the whole time. I repeated the test at 325F to verify the "from below" and "from above" setting differences. I also did two tests at 400F to see if the settings and swings were consistent. (They were.) I think you could do a reasonable test in half the time I took, possibly even less.
 
That's why I (and other "dutch oven" bread makers) wait 30-45 minutes AFTER the oven clicks "off" before putting our bread in to the d.o. to start baking. Ensures not only the oven but also the d.o. is up to temp.

Good to know in general though ;)
 
Good stuff, thanks Jay. I suspect, though haven't verified that my oven runs about 25F degrees above setting.
 
I tested mine this past week. It was a new Samsung gas range. Things seemed to be cooking slow. Turns out that it was running about 25-30 degrees below the set temperature. I checked the manual and there I a actually a way to caliber are to adjust the displayed temp +\- 30 degrees. I haven't done that yet but plan to soon.
 

 

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