Oven Temp, Frigidaire Elec. Range, Model FEF357CESE

[Norminn]

Just bought a home with the electric range. Oven temp is way too hot,

50-75 degrees. Turned it on about an hour ago to 300, and oven thermometer is consistently reading 350. Seemed on T'giving it varied more, but there was a huge turkey in the oven and the door opened regularly. I'm wondering if anyone has a manual that gives the codes for calibrating the oven temp setting? I've not used the oven a lot, but have burned a pie and muffins :o) Another issue with this range is that when I opened the oven door to ck the turkey, I got hit in the face with a blast of steam...never had that happen, gas or electric. I'm all for getting gas range ASAP, as there is no longer parts avail. for this one.

[dpb]

On 11/26/2012 11:50 AM, Norminn wrote: ...

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[nestork]

You should be aware that ovens purchased within the last 20 years no longer use thermostats to control their temperature.

Nowadays, they use a thermistor in the oven. The resistance of the thermistor varies very precisely with temperature, and the circuit board in the oven console measures that resistance and determines the corresponding temperature in the oven.

It's possible that the thermistor is gone and you need a new one. If I recall correctly, at room temperature, the thermistor should have a resistance of 1000 ohms. Maybe take the thermistor out of your stove (it looks kinda like an oil filled capillary bulb, but shorter) and take it down to your local Frigidaire factory authorized service depot and have them check it for you. There won't be any charge for that.

While it's possible the thermistor is shot, it's probably more likely that the someone has programmed the oven to operate at a higher temperature. You see, one of the most common complaints customers have is that their new stove "just doesn't bake (or broil) like the old one did", and the usual cause of that is that the old stove had an oil filled thermostat bulb, and that thermostat was out of whack by 50 or 60 degrees.

So, to address those complaints, programmable ovens can be set so that they will automatically add or subtract a certain number of degrees to the temperature you set the stove at so that it will mimic the behaviour of the customer's old stove. So, if you're used to baking cookies at

350 degrees on an old stove whose thermostat was so far out of whack that when you set it at 350, the actual oven temperature would only be 300, then you can program your new stove to subtract 50 degrees from whatever temperature you set. So, when you set the stove to 350, it'll actually bake the cookies at 300, just like the old stove did.

I suspect that either the previous home owner or someone just mucking about with the stove got into the programming menu and changed the oven offset temperature.

I agree with the previous post to go to Jeff's website at ApplianceAid.com and get his input on it. Jeff's an appliance repair technician, so he's probably be very familiar with Frigidaire stoves.

Also, you should know that the temperature within the oven will vary by a good 25 degrees from the front to the back and from the bottom to the top. You're always going to get some variation between the temperature reading of an oven thermometer that stays inside the oven during baking if for no other reason than the thermometer is located at a different location than the thermistor. However, if you're using an oven thermometer that uses a clip that you clip to the oven rack, clip it to the thermistor instead. That way your oven thermometer will be at the same location as the thermistor, and both your thermometer and the oven digital read out should be within a degree or two of each other.

[hrhofmann]

Have you pulled the oven knob off the range to see if there is an adjusting screw opening behind the knob? If there is, give the screw a 1/2 turn and see if the oven temp is closer or farther away from the knob indication. Then keep turning the screw in the appropriate direction until the knob and the temp agree +/- 10 - 15 degrees.

[gregz]

My furnace thermostat works just fine.

OK, temperature controller.

Thermistors come in various ohm's, but generally not used for high temps, but i guess there might be some. Platinum wires or thermocouples are usually used in high temps, but I don't know what the oven makers use.

Greg

[dpb]

On 11/27/2012 11:14 AM, Norminn wrote: ...

So, you went the wrong way, apparently. Do the same thing except the other direction. I'd recommend a single step at a time.

I've never had any trouble getting an electric oven to hold temperature well near enough to setpoint...

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[Norminn]

It had that much variation when I baked pies for T'giving...I'm done :o)

[trader4]

It sounds lie all the adjustment procedure does is move the relative position of the know to the shaft. In which case, it would have to work. Unless something is screwed up in the thermostat so that it's intermittent, not consistent, etc.

[dpb]

On 11/27/2012 12:05 PM, [e-mail] wrote: ...

Correct...

The setpoint adjustment will bring the steady-state temp to near the indicated.

If there is an excessive variation in temperature at what should be steady-state, that's not a calibration issue.

[Smitty Two]

Go ahead and get the gas range, but don't blame the technology for your choice. And yes, you did, obviously, turn the adjustment the wrong way.

I actually know something about temperature control, having designed a few pieces of industrial equipment that use temperature controllers. Inherent in any control system is some fluctuation above and below the set point. Fancy word for that is hysteresis.

The thing about gas vs. electric with an oven is that the hysteresis band can be much smaller with electric, because it's easier to proportion the heater power. You'd be shocked at the width of the temperature swings inside that gas oven of your dreams.

The thing about gas vs. electric with a cooktop is that although it's much easier to precisely set a desired temp with electric, there is a huge delay in response when you want to change that temperature. With gas it's instantaneous, (not counting the thermal mass of whatever you're cooking.)

Many people who love to cook choose the best of both by buying a dual fuel range: gas cooktop and an electric oven. You might consider it.

[Norminn]

Obviously? You are dreadfully wrong....turned to lower the temp, per the little arrow markings. This range seems to have very small vent, below the panel on top of stove....even after reaching high heat, holding my hand at the vent I can barely feel a difference in temp from room temp. When I was roasting turkey on T'giving, opening the oven door to baste the turkey gave me a blast of steam in the face...never experienced that with any other oven (I've roasted turkeys for many years).

Well, shucks, I have cooked with gas ranges for.....hmmm....a total of about 45 years, beginning rather young. No problems. Cooked with three other electrics, few years, no problems. One gas range I used for a couple of years was way off temp setting (too hot), but the temp was consistent so it was easy to simply set oven temp to lower temp.

Thanks, but I much prefer gas.

[dennisgauge]

Yes, obviously. You turned it the wrong way.

The direction you turned it causes the dial to INDICATE a lower temperature for the position of the control. Turn it the other way to cause the dial to indicate a *higher* temperature.

Also, your vent is plugged, which is why you're getting this "blast of steam" you're hell-bent on obsessing about.

But you're gonna chuck the oven anyway, so why cop an attitude over it? You asked the question. Don't act like a petulant know-it-all when someone gives you the answer.

[Norminn]

for the position of the control. Turn it the other way to cause the dial to indicate a *higher* temperature.

Guess I missed you lookin' over my shoulder whilst I did the adjusting. It APPEARS that the dial setting is not proportional to the excess temperature and the temp varies a great deal.....a sign the sensor thingy is shot?

you're hell-bent on obsessing about.

Steam burns aren't fun, and opening the oven is like taking the lid off a boiling pot while facing right into it. I'm not obsessing about it, just feel it is unusual. Per my uneducated glance at schematic for the range, there is only a small (1"?) tube venting the oven....can't see the opening of the vent atop the range, as there is a steel flange sticking out of the opening.

asked the question. Don't act like a petulant know-it-all when someone gives you the answer.

Ditto.

[bob haller]

most older thermostat controls..........

pull knob, see hole in middle of shaft use small jewlers type screwdriver to turn that screw buried in hole.....

over the years of my job i have made thousands of adjustments to thse type thermostats on dry mount presses and t shirt presses

[gregz]

Gas ovens produce more kitchen heat, because it's vented into the room. Electrics have minimal venting.

Greg

[WRP]

I checked the accuracy of the oven temperature of a new stove when I purchased it a few years ago, using a calibrated thermocouple readout with an accuracy of +/- 2°F. I placed the probe in the centre of the oven and monitored the temperature to see the variability at set points of between 250 and 450°F. I was quite surprised at the huge cycle swings in the oven's temperature.

I found the controller cycled on and off within +/- 25°F of the set point, with an additional lag of 25°F in the response of the elements, for at total cycle range of +/- 50°F, over a total cycle time of something like 20 or 25 minutes. Although it was difficult to measure with the big cycles, I estimated the average temperature would have been close to the set point. I wish I would have checked the oven in convection mode to see how much it affected the cycle profile. If I do this test again, I'll use a less responsive oven thermometer, as long as I check its accuracy first. Ovens have their control sensors immersed in an oil bulb to temper these swings and somewhat mimic the response of food cooking.

I suspect this is typical performance for an electric range and it works well for me as my food typically cooks in the expected time.

[gregz]

I don't know how long you waited for the thing to stabilize. You would normal put the test sensor where the other sensor is. Sensor response should be fast. Makes no sense to be slow. A good controller will determine the on/off points, not the sensor. It can also use PID which acts to control overshoot and would know the response of the heater elements. Question is, do any models have good controllers.

I don't understand why you didn't test turbo oven mode. I can't even get even temperature in a beaker of water unless it's being rapidly stirred.

Greg

[gregz]

I would not doubt large swings. I never measured a home oven, although I have done a lot of measurements with lab equipment. A gas oven is most always on/off, but an electric oven could use pulsed currents to vary the heating element average wattage. I guess most people are used to averages in oven timing.

Greg

[nestork]

I'm quite sure the temperature sensors in my ovens are thermistors. I don't think they'd use thermocouples because thermocouple voltages gradually diminish with use. This is why the thermocouple is the prime suspect if your water heater or furnace pilot light keeps going out. Thermistor resistance doesn't change that way, and so that predictability would make a thermistor better suited for use as a temperature sensor than a thermocouple.

WRP: My sister was upset when she used an inexpensive supermarket oven thermometer to check the accuracy of the temperature in a brand new stove she had purchased just about two years ago now. It was off by at least 20 degrees; probably more. I borrowed her my digital oven thermometer, and she clipped the probe to the middle of the oven rack as the users manual for the digital thermometer recommended, but she was still getting readings that were considerably different than those displayed on the stove's console. It wasn't until she clipped the probe to the thermistor inside the oven that she got agreement between the two digital displays as to what the oven temperature was at any given time. But, in that case, she was really using my oven thermometer to measure the temperature of the oven's thermistor. But, that shows that the oven's thermistor isn't reading the temperature in the middle of the oven (where the food generally is), but in the top left rear corner of the oven, where the thermistor is, and she found a lot of difference in temperature between those locations.

[Smitty Two]

Cite? We aren't talking about blast furnaces, here. A type J thermocouple will hold up just fine for the duty cycle and temperature range of a home baking oven. I don't actually know or care what's typically used, but the theoretical aging drift of a thermocouple is a moot point here.