Hot or not?
January 21, 2020 4:06 PM   Subscribe

I had a theory that my oven was running cold. This was based on an observation that everything takes much longer to cook than recipes say. This is true across multiple types of food, and has been observed by several people. Yesterday, I borrowed a Fluke thermometer with a probe from a friend who works in a science lab and.... if anything my oven runs hot?!?!? I'm sitting here watching the temperature oscillate from a little below to somewhat (10 degrees) above the target temperature. So, what is going on and can I fix it?
posted by papergirl to Home & Garden (16 answers total) 4 users marked this as a favorite
What's your elevation?
posted by Nonce at 4:12 PM on January 21, 2020 [5 favorites]

I was just reading about ovens in Salt Fat Acid Heat. They're imprecise - your oven doesn't just go up to a set temp and stay there. If you set it to 350, it may go to 370, cool down to 330, then bump back up to 370, and continue that cycle throughout cooking. There are also likely hotter/cooler areas of your oven depending on where the heating elements are.
posted by gnutron at 4:14 PM on January 21, 2020 [4 favorites]

How long do you preheat for?
posted by purpleclover at 4:19 PM on January 21, 2020 [4 favorites]

I wonder how big the swings are once you put something in to cook... Maybe it takes longer to swing back up then, making your cooking times longer. Add some mass (something to cook) and do the test again!
posted by purple_bird at 4:32 PM on January 21, 2020 [3 favorites]

As others have said, ovens have a pretty variable swing surrounding the target temperature. Convection ovens are sometimes better, gas ovens are mostly often worse. Stoves trick us into thinking they’re precision machines, when in fact they are not (which drives me bananas). My current range is actually 30F hotter than the “knob temp” states. Fortunately, it’s pretty steady and has a pretty low temperature swing, this easy to adjust for.

In a rental unit I had years ago, the temperature swing in the shitbox oven I had was almost 40F in both directions from the set temperature. It drove me up the wall because the swing was enough to stall, then scorch whatever i was making. I ended up using pizza stones (but unglazed masonry tiles are cheaper and work just as well) on extra racks in the oven; one for the top and one for the bottom, with more coverage being ideal. It takes more time and energy to preheat, but the stones even out any temperature swings your oven has. Extra bonus, this often irons out any spots in the oven heating unevenly as well, so rotating things halfway through is completely unnecessary. My wife uses the two-stone technique still when doing things that are ultra thin, like lace cookies or other wafer thin friends.

Sometimes the knobs on certain ovens have a set screw that you can use to adjust where your knob is set to. Process goes like so; preheat the oven to A Temperature (any is fine, but I usually try to peg mine out at 350F as that’s where loads of recipes direct you towards), and let it sit for a while. Use your borrowed thermometer to measure the average of where it sits (with the door closed! Door opening can trigger the heating mechanism in some stoves by heat loss or by mechanism). Then you set the knob to that temperature, giving you a closer measurement than you had prior.
posted by furnace.heart at 4:47 PM on January 21, 2020 [7 favorites]

Have you checked for hot/cold spots? Basically you can spread sliced bread all over the racks, cook for a bit and monitor which bits get cooked quicker.
Google Image Search of what I mean.
posted by freethefeet at 5:06 PM on January 21, 2020 [2 favorites]

Best answer: How were you using the Fluke temperature probe? If you placed it exposed to the heating elements (electric or gas) then you would get inaccurate readings. Every time the heating elements turned on, the probe would be heated by direct infrared radiation and give a higher temperature than the air in the oven.

You want to shield the probe from direct exposure and make sure it is not touching a metallic object. Or just get yourself a cheap $5 oven thermometer. They should be accurate enough for your purposes and are shielded from direct heat.
posted by JackFlash at 5:32 PM on January 21, 2020 [8 favorites]

As an aside, if stuff is taking much longer to cook than recipes say, is it because it's in thick cookware or are you otherwise insulating it somehow? I find that when I cook stuff in e.g. a glass pyrex dish it takes much longer than a metal pan.
posted by ropeladder at 6:27 PM on January 21, 2020

Jeff Potter has a nice set of instructions for calibrating your oven using sugar. You could also use this technique to check for hot and cold spots.
posted by Winnie the Proust at 6:32 PM on January 21, 2020 [2 favorites]

My gas oven takes longer than it's supposed to bake things. I've found that setting the temperature 25 degrees higher than the recipe calls for (i.e., 375 degrees instead of 350) corrects for that, and then things usually cook/bake in the recommended time.

I also find that I need to rotate the pans so that the food will bake evenly. If I put two dozen muffins in the oven to bake for twenty minutes, I set the timer for ten minutes and switch the muffin tins from their respective places on the top/bottom rack at the ten minute mark, then set the timer for another ten minutes. Sometimes at the twenty minute mark the muffin tin that is on the bottom rack may need another two minutes on the top rack. If I'm only putting one pan of something in the oven, or two small pans, I always use the top rack, as things cook faster there.
posted by orange swan at 6:46 PM on January 21, 2020

Best answer: Not to go against what's been said so far, but to add another thing to consider: Across multiple households at multiple elevations between sea-level and ~3000 ft, and for multiple cookbooks, I generally find that the cooking times given in recipes are...optimistic. Less so for short-cooking dishes, and more so for bigger/longer-cooking things like chickens, roasts, etc. Part of your solution may be to stay aware of that and compensate as needed. For determining whether a dish is done or not, a target internal temperature is far more useful than cooking time. An instant-read probe thermometer, even an inexpensive one, is a very worthwhile investment.
posted by Greg_Ace at 6:50 PM on January 21, 2020 [12 favorites]

Best answer: Across multiple households at multiple elevations between sea-level and ~3000 ft, and for multiple cookbooks, I generally find that the cooking times given in recipes are...optimistic.

That's my experience too. On average, I have to bake cakes 10 to 20 minutes longer than the recipe says, and this has been consistently true for the same recipes across many ovens I've used, while other recipes have always cooked in the "correct" time. Around the fourth oven I experienced this with, I decided that lots of recipes are just wrong about baking time. (Lord knows they're often wrong about how long other operations take -- see any recipe that gives you 10 minutes to caramelize onions, or even 30 for that matter.)
posted by aws17576 at 8:28 PM on January 21, 2020 [2 favorites]

Nthing usage of probe thermometer. Got the Meater couple years ago. It’s changed my life. It talks to my phone and tells when target temp has been reached. No longer trapped in kitchen or timers. Joy.

As far as temperature variation/hysteresis, residential ovens have +/- 20F if well-calibrated. And that calibration is performed at sensor location only.
posted by lemon_icing at 8:35 PM on January 21, 2020

You do know that recipe times are like vanity sizing in garments, right? Cooks in 5 minutes? Make sure you have a free hour. 1 hour beef stew? Bullshit. 20 minute turkey? Suck my drumsticks, you LIARS.
posted by sexyrobot at 2:33 AM on January 22, 2020 [5 favorites]

The father of a friend of mine is an electrical engineer. When he started taking an interest in baking, he ended up swapping out the thermostat in his consumer oven to something more reliable, after managing to get one of the engineers at a well-known oven manufacturer on the phone and pumping them for information.
posted by Harald74 at 4:55 AM on January 22, 2020

Response by poster: After further experimentation shielding the probe from direct heat (thank you JackFlash for your astute comments), I'm concluding that the oven does run a touch low, but really, Greg_Ace and aws17576 are probably the most right, that the issue is unrealistic recipe writing. Thank you.
posted by papergirl at 5:45 AM on January 23, 2020

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