Bipolar Oven
July 28, 2014 11:32 AM   Subscribe

My oven is bipolar: when I follow the instructions for frozen pizza, it's done in about 66% of the time, i.e. instructions say 18min, it's done in 12, usually less - 18min would burn it to a crisp. Thicker things, like pork roasts or heating a pre-cooked ham, are barely tepid in the center at the time in their instructions, i.e. instructions say 45min, takes over an hour to get to the recommended temperature. The oven is a generic, in-every-apartment-I've-ever-had kind of stove. What's it's problem?

Preheating and all recipes and instructions are followed exactly, and it's consistent across different items and whether it's 350` or 450`; for example, porkchops count as "thin" and are done early; cookies, rolls, etc are "thin" as well, Banquet fried chicken is done sooner too, but closer to actual time. Baked potatoes (various varieties of potatoes) count as "thick" so they take about 1-1/2 hours despite cookbooks saying 1 hour is enough. It seems weird that, despite following directions, thin things are always crispified while thicker things never get cooked through. Is the stove wonky, or is there something I'm overlooking in its care and operation?
posted by AzraelBrown to Food & Drink (16 answers total)
Best answer: Do you have an oven thermometer? Is your oven actually getting to the temperature it says it is? Is it staying there? Is it consistent across different zones of your oven? This is a good first check, and a $6 investment.
posted by brainmouse at 11:34 AM on July 28, 2014 [3 favorites]

Best answer: Seconding getting an oven thermometer. Sometimes your oven can be off in different places.
posted by EmpressCallipygos at 11:36 AM on July 28, 2014 [2 favorites]

Best answer: Do you have an oven thermometer? I'd buy one and keep it in your oven, all the time. If you don't have a thermometer there's no way to know what temperature it is REALLY heating up to. Most ovens that I have worked with have their own personality quirks--some 25 degrees hotter, some cooler, and you really need a thermometer to be able to tell.

Plus, electric ovens often cycle and you will have hotter periods in the oven as it cranks the heat, then the temperature might drop until the next heating cycle. Here's some info about calibrating your oven if you're interested:
posted by Bella Sebastian at 11:37 AM on July 28, 2014 [1 favorite]

Best answer: in addition to nthing the "get an oven thermo" advice, I'd ask: how are your rack positions when baking, and does this oven have a convection feature that may be misbehaving ?
posted by k5.user at 11:41 AM on July 28, 2014 [1 favorite]

Best answer: It does sound like the internal thermometer is messed up, which means that even if you get an oven thermometer and you find it's off, it might not be consistently off, or off in a way that you can calibrate yourself. You might have some luck recalibrating it, but if it's really messed up you might need a service visit.
posted by thewumpusisdead at 11:42 AM on July 28, 2014 [1 favorite]

Not related to your specific oven, but when you're cooking roasts and other thick meat dishes, are you taking them out of the refrigerator an hour or so before you cook them and letting them come up to room temperature before you cook them in the oven? If try to cook a roast straight into the oven from refrigerator temperature, it will take longer to cook than it should and come out too dry, although letting the meat temper first might or might not be called out in any particular recipe.

This wouldn't apply to things like frozen pizza that you're supposed to put in cold, and would have less effect on thin meats like pork chops.
posted by strangely stunted trees at 11:44 AM on July 28, 2014 [2 favorites]

Is it an electric oven?
posted by I-baLL at 11:47 AM on July 28, 2014

If your oven is dirty, that can also affect how the heat is distributed and, theoretically at least, could produce the results you're describing. As she shuffles off to, finally, clean her own filthy oven.
posted by DrGail at 11:58 AM on July 28, 2014 [2 favorites]

This article on the Joy of Cooking talks about how to find hot spots in your oven, among other things.
posted by soelo at 12:08 PM on July 28, 2014

Best answer: It sounds to me as if, when you turn your oven on it keeps heating and heating far beyond the set temperature, until it reaches a very high level, then turns off for a very long time which causes it to cool far below the set temperature and stay that way for a while.

This could happen if your thermostat (the thing you set the temperature with by a dial in older models) never turns off once you turn it on, and the oven is finally turned off only by a backup temperature-sensitive circuit breaker designed to trip only at very high heat in order to prevent fires. Such a circuit breaker often takes quite a long time to reset itself after the heat goes down, but once it does, the oven turns back on and the cycle repeats itself.

So I think you need a new oven thermostat.
posted by jamjam at 12:23 PM on July 28, 2014 [6 favorites]

If this is an electric oven- my folks had the same issue recently. Some internal sensor had broken so it was cycling very widely. Like usually you set the temperature to 300, and it heats up to 310, then cools down to 290, then the heat kicks on again and it goes back up to 310, and continues cycling like that, meaning the average temp is 300 and pretty much any food can handle that little variation. Theirs was set at 300, but going to 330, cooling to 250, then up to 330 again- the same average temperature, but the variation was so wide that thick stuff like meats would be cooling dramatically while on the cool end of the cycle and cookies burned at the hot end. This frustrated my mother so much! It sounds a lotlike her problem and it took a few months to diagnose.
The technician verified this via some kind of point/shoot electronic or infrared thermometer used every few minutes during a 20 minute cycle. Their liquid filled thermometer read that the oven was normal temp (because the liquid in a regular oven thermometer reacts slowly, it will not move fast enough to get the cycling temperature).
posted by holyrood at 12:29 PM on July 28, 2014

Best answer: I found that when my oven beeped to indicate that pre-heated was done it was still 25 degrees cooler than the selected temperature. After a few more minutes everything was normal. I only knew that because I got that oven thermometer, just like everyone is suggesting.
posted by Phredward at 12:55 PM on July 28, 2014 [1 favorite]

Best answer: Yeah, presuming this is an electric oven, it sounds like your thermostat is out of whack and it's not cycling correctly.

If you want to check for hotspots, though, one simple way to do it is to take a loaf of wonder bread and fill a cookie sheet with them, then set it in a preheated oven to toast for 5 or ten minutes. The variation in the browning on the surface of the bread will tell you whether, say, the front of your oven is much cooler than the back, etc. Just be sure to keep an eye on it --- leave it too long and every slice will be burnt.

This could also be contributing to the cycle whackiness --- if you have a hotspot near the thermostat it could be triggering it to cycle off before the rest of the oven is properly warmed up.
posted by maggiepolitt at 12:55 PM on July 28, 2014 [1 favorite]

Are the "fast" items cooked on a pan that is wide and deep relative to the size of the oven? Most people's thermostat sensors are at the top of the oven and the heating element is at the bottom, so if the hot air can't get around the pan to the thermostat, it would be over-temperature. Then you would tend to see the bottom overcooked.
posted by wnissen at 3:24 PM on July 28, 2014

I've noticed this with pizzas and ovens before.
The rule on pizzas is always 420 degress for 12 mins.
posted by QueerAngel28 at 5:08 PM on July 28, 2014

Response by poster: OK, oven thermometer it is! The thermostat not turning on / not turning off at the right temperature/times seems like a likely candidate. I'm just renting, this is the second stove we've had, and I think we inherited it from a different unit, so it's entirely possible the reason it was not being used was because it cooks wonky. Thanks everyone!
posted by AzraelBrown at 6:50 AM on July 29, 2014

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