How much can an oven's temperature vary and still give good results?

If set at 350 degrees F., what is the most it should go above or below the
set temperature?
Is there actually a standard or "generally accepted range"?
Is the acceptable range a percentage of the target temperature (e.g. up or
down 5%) or is it an absolute (e.g. up or down 10 degrees F maximum?)

My oven is way out of whack, can vary as much as 150 degrees too low and 39
degrees
too high when set at 250 deg F (yep, down to 100 and up to 289!) and +/- 70
degrees when set at 350.
Obviously this is crazy and totally unacceptable, but I need to know what is
acceptable for good
reliable baking. The repair people are worthless in this regard, and I'm
sick and
tired of throwing out food, as one time it burns, the next it is raw, and
sometimes it comes out with an additional hour of oven time!

I've searched the internet for weeks and found NOTHING even remotely like an
industry
standard, nor can I find a "rule of thumb" standard in any baking/cooking
site, so far.
I posted this message to rec.food.baking and they told me about
this group (much more likely to know).
Please help!

TIA
Bob in Los Angeles

Bob Giel wrote:
> How much can an oven's temperature vary and still give good results?
>
> If set at 350 degrees F., what is the most it should go above or below the
> set temperature?
> Is there actually a standard or "generally accepted range"?
> Is the acceptable range a percentage of the target temperature (e.g. up or
> down 5%) or is it an absolute (e.g. up or down 10 degrees F maximum?)
>
> My oven is way out of whack, can vary as much as 150 degrees too low and 39
> degrees
> too high when set at 250 deg F (yep, down to 100 and up to 289!) and +/- 70
> degrees when set at 350.

Boy. Good question Bob and I don't know the definative
answer but given your temperature swing, I'd say that you
have serious problems. My GE electric varies plus or minus
5dF according to an unbias oven thermometer.

--
Steve

If you can't beat 'em, they're not tied down properly.

On Mon, 02 Jan 2006 01:35:04 GMT, "Bob Giel" >
wrote:

>How much can an oven's temperature vary and still give good results?

If the oven is consistently off by x degrees you can adjust with
little problem. If it varies +/- 25 inconsistently you have an
insurmountable problem.
------------
There are no atheists in foxholes
or in Fenway Park in an extra inning
game.
____

Cape Cod Bob

Delete the two "spam"s for email

> On Mon, 02 Jan 2006 01:35:04 GMT, "Bob Giel" >
> wrote:
>
>
>>How much can an oven's temperature vary and still give good results?
>

How old is the oven in question ?

donald

"Bob Giel" > wrote in message
nk.net...
> How much can an oven's temperature vary and still give good results?
>
> If set at 350 degrees F., what is the most it should go above or below the
> set temperature?
> Is there actually a standard or "generally accepted range"?
> Is the acceptable range a percentage of the target temperature (e.g. up or
> down 5%) or is it an absolute (e.g. up or down 10 degrees F maximum?)
>
> My oven is way out of whack, can vary as much as 150 degrees too low and
> 39
> degrees
> too high when set at 250 deg F (yep, down to 100 and up to 289!) and +/-
> 70
> degrees when set at 350.
> Obviously this is crazy and totally unacceptable, but I need to know what
> is
> acceptable for good
> reliable baking. The repair people are worthless in this regard, and I'm
> sick and
> tired of throwing out food, as one time it burns, the next it is raw, and
> sometimes it comes out with an additional hour of oven time!
>
> I've searched the internet for weeks and found NOTHING even remotely like
> an
> industry
> standard, nor can I find a "rule of thumb" standard in any baking/cooking
> site, so far.
> I posted this message to rec.food.baking and they told me about
> this group (much more likely to know).
> Please help!
>
> TIA
> Bob in Los Angeles

Not really an answer, but..........
From Cook's Illustrated (part of article):

Conversations with David Anderson, senior product manager at Whirlpool,
revealed that the average oven designed for home use does not simply heat up
to the temperature set on the dial and then stay there. Anderson noted that
an oven's heating elements are either on at full power or off-with no middle
ground. To maintain the desired temperature, the heating elements cycle
within a manufacturer-determined tolerance, heating up and cooling down to
temperatures just above and below the desired temperature. The precise
temperature tolerances and timing of the cycles vary from manufacturer to
manufacturer. For instance, Anderson said that Whirlpool uses one-minute
intervals, so the elements will be on for one minute, then off for the next,
then on again, and so forth as necessary. This cycling process is regulated
by an internal temperature sensor located in the oven cavity.

We wanted to put this information to the test, so we hooked up our ChartScan
Temperature Data Recorder to an electric oven in the test kitchen and
programmed it to record the temperature once every 10 seconds for 1½ hours.
We placed 15 temperature sensors, called thermocouples, at different
locations up and down and side to side in the oven cavity and set the dial
to 350 degrees. At the dead-center location in the oven, we found the
temperature cycled within a range of roughly 25 degrees, from a low of about
335 degrees to a high of about 361 degrees. We analyzed a gas oven in the
same manner and found the temperature spread to be somewhat narrower,
between 343 and 359 degrees.

A careful look at the numbers generated by our ChartScan tests also
confirmed the common assertion that the heat within an oven cavity is not
consistent; that, in effect, there are hot and cold spots. Though we might
have suspected otherwise, we found that the bottom of our electric test oven
tended to run hotter than the top, usually by between 5 and 15 degrees. We
also found that the rear of our oven ran hotter than the front by roughly 5
to 10 degrees. There was also a stunning difference from right to left in
our oven, with the right side sometimes running up to 50 degrees hotter than
the left!

The uneven heat is the reason why many cookbook authors suggest rotating
pans in the oven when you bake. We ran a simple test of baking sugar cookies
to confirm this advice. Sure enough, the cookies were browned a little less
evenly from one side of the pan to the other when we failed to turn the
cookie sheet partway through the baking time.

Curious as to whether there was any truth to the common kitchen wisdom that
electric ovens heat more evenly than gas ovens, we repeated the ChartScan
tests on a gas range in the test kitchen. The temperatures recorded in our
tests bore out some validity in this axiom. For instance, the temperature
differential between the bottom and top of the cavity was closer to 50
degrees, where it had been just 5 to 15 degrees in the electric oven.

In "Douglas Reynolds"
> wrote:

> Anderson noted that an oven's heating elements are either on at full
> power or off-with no middle ground.

In this age of cheap semiconductors, why ->don't consumer ovens have
"proportional controls"?

I'd think that solid-state temperature controls would be cheaper and
more reliable than the relay switching that's used now.

Or, maybe the newest ones do; our Thermador oven is 5 years old.

--
Bert Hyman St. Paul, MN

Bert Hyman wrote:
> In "Douglas Reynolds"
> > wrote:
>
>
>> Anderson noted that an oven's heating elements are either on at full
>> power or off-with no middle ground.
>
>
> In this age of cheap semiconductors, why ->don't consumer ovens have
> "proportional controls"?
>
> I'd think that solid-state temperature controls would be cheaper and
> more reliable than the relay switching that's used now.
>
> Or, maybe the newest ones do; our Thermador oven is 5 years old.
>

I don't know if the controls in my one year old GE wall oven are solid
state or relay, but they certainly appear to be proportional to some
degree. The coils never appear to be fully on except during the self
clean cycle.

Matthew

--
What if you arrived at the fountain of youth, only to find dead toddlers
floating in the pond? -- John O on AFB

"Bert Hyman" > wrote in message
...
> In "Douglas Reynolds"
> > wrote:
>
>> Anderson noted that an oven's heating elements are either on at full
>> power or off-with no middle ground.
>
> In this age of cheap semiconductors, why ->don't consumer ovens have
> "proportional controls"?
>
> I'd think that solid-state temperature controls would be cheaper and
> more reliable than the relay switching that's used now.
>
> Or, maybe the newest ones do; our Thermador oven is 5 years old.
>
> --
> Bert Hyman St. Paul, MN

Solid state power control is basically like what you get with a light dimmer
switch. The sinusoidal voltage is turned on and off during the sine wave to
achieve a reduction in power. In the oven the relay switches the power on
and off too, but since heat in the oven reacts more slowly than a lightbulb
on the retina, the switching can be done slower too. So there's really no
benefit in applying the technology. Relays seem to be good enough that they
don't need service also.

In "FDR"
> wrote:

>
> "Bert Hyman" > wrote in message
> ...
>> In "Douglas Reynolds"
>> > wrote:
>>
>>> Anderson noted that an oven's heating elements are either on at
>>> full power or off-with no middle ground.
>>
>> In this age of cheap semiconductors, why ->don't consumer ovens have
>> "proportional controls"?
>>
>> I'd think that solid-state temperature controls would be cheaper and
>> more reliable than the relay switching that's used now.
>>
>> Or, maybe the newest ones do; our Thermador oven is 5 years old.
>>

>
> Solid state power control is basically like what you get with a light
> dimmer switch. The sinusoidal voltage is turned on and off during the
> sine wave to achieve a reduction in power.

Well, that's one way to do it.

> In the oven the relay switches the power on and off too, but since
> heat in the oven reacts more slowly than a lightbulb on the retina,
> the switching can be done slower too.
> So there's really no benefit in applying the technology.

Of course there would be, assuming that a continuous temperature in the
oven that actually matched the temperature you set it for is a
"benefit".

Simple full-on/full-off switching of the heating element causes
significant temperature over and undershoots, although the long-term
average might match the dial setting.

A proportional control could apply full power to the cold oven, reduce
power as the oven approached the desired temperature and then continue
to apply just enough power to maintain a constant temperture in the oven
to balance heat loss.

Would you accept a stove-top element that only had a full-on or full-off
setting?

> Relays seem to be good enough that they don't need service also.

Relays, being mechanical with moving parts, break far more often than
conservatively designed power control circuits would.

--
Bert Hyman St. Paul, MN

"Bert Hyman" > wrote in message
...
> In "FDR"
> > wrote:

> Simple full-on/full-off switching of the heating element causes
> significant temperature over and undershoots, although the long-term
> average might match the dial setting.
>
> A proportional control could apply full power to the cold oven, reduce
> power as the oven approached the desired temperature and then continue
> to apply just enough power to maintain a constant temperture in the oven
> to balance heat loss.

That sounds like a good idea to me. Would this be expensive to implement?
I would also think that it would prolong the life of the heating element in
the same way that dimmers prolong the life of light bulbs.

"Bert Hyman" > wrote in message
...
> In "FDR"
> > wrote:
>
>>
>> "Bert Hyman" > wrote in message
>> ...
>>> In "Douglas Reynolds"
>>> > wrote:
>>>
>>>> Anderson noted that an oven's heating elements are either on at
>>>> full power or off-with no middle ground.
>>>
>>> In this age of cheap semiconductors, why ->don't consumer ovens have
>>> "proportional controls"?
>>>
>>> I'd think that solid-state temperature controls would be cheaper and
>>> more reliable than the relay switching that's used now.
>>>
>>> Or, maybe the newest ones do; our Thermador oven is 5 years old.
>>>
>
>>
>> Solid state power control is basically like what you get with a light
>> dimmer switch. The sinusoidal voltage is turned on and off during the
>> sine wave to achieve a reduction in power.
>
> Well, that's one way to do it.
>
>> In the oven the relay switches the power on and off too, but since
>> heat in the oven reacts more slowly than a lightbulb on the retina,
>> the switching can be done slower too.
>> So there's really no benefit in applying the technology.
>
> Of course there would be, assuming that a continuous temperature in the
> oven that actually matched the temperature you set it for is a
> "benefit".
>
> Simple full-on/full-off switching of the heating element causes
> significant temperature over and undershoots, although the long-term
> average might match the dial setting.
>
> A proportional control could apply full power to the cold oven, reduce
> power as the oven approached the desired temperature and then continue
> to apply just enough power to maintain a constant temperture in the oven
> to balance heat loss.
>
> Would you accept a stove-top element that only had a full-on or full-off
> setting?

A stove top element has a much much quicker response time, and would need to
be more tightly regulated. An oven doesn't need the same regulation. Aslo,
the stovetop works by you regulating the temperature, whereas in an oven you
set the temperature and let the oven maintain that temperature. They are
two totally different environments.

As inaccurate as a stove may be, they really don't need to be dead on for
your baking to work. Now if as the OP siad that he never gets anything to
really cook right and the fluctuations are really large, then you will have
problems. But even the lowest tech gas ovens from years ago could make a
good cake or roast.

>
>> Relays seem to be good enough that they don't need service also.
>
> Relays, being mechanical with moving parts, break far more often than
> conservatively designed power control circuits would.
>
> --
> Bert Hyman St. Paul, MN

Thanks to the group for all the great information. Wow, do I have trouble!

I do not understand how the age or type of oven would have anything to do
with the question of acceptable temperature ranges.
Does the food care if the oven is gas or electric or hardwood under brick?
What I thought should matter is the allowable temperature fluctuations.
Then the trick is to get the oven to operate within those limits.

Since I may be all wrong about this, here is the info some requested along
with a warning about really horrible service:

This particular oven is a Maytag Gas, with an additional electric top
element for HIGH broiling only, (not used for baking or convection
operations) It is Very High End for home use but not too many bells and
whistles (e.g. no grill, or griddle, or charbroiler) just an oven and four
burner gas range top. It is high end for home, but nowhere near the
industrial or restaurant grade! It is now about three years old. The unit
is supposed to be state-of-the-art solid-state technology (therefore,
quicker and more accurate temperature control at all settings (LOL), but
somebody forgot to tell the oven!) I bought the thing at Sears and went out
of my way to get the best, even though it was well above budget. This
problem has existed literally since day one. So far, we have had two ruined
Thanksgiving Turkeys, (literally used my BBQ and Coleman camp stove to
finish the meals, a few hours late!), countless ruined meals, and have
thrown out 85% of everything attempted in the oven, the other 15% barely
passing as edible.

Sears has been less than worthless in its repair or maintenance coverage.
The worst thing I ever did was buy their Maintenance Agreement (so far this
last round of non-repair from their customer NO-service department is taking
more than six weeks, with no end in sight.) FYI my clothes washer has been
out even longer than that and both are still inoperative.

Each time they come out, they pretend too tickle the appliances. They use a
shotgun approach, (never even take out a multi-meter!) and order ONE (and
only one) of the many "possible it could be any one of these bad parts"! I
notice they usually order the least likely but the easiest to replace part.
Then they re-schedule service for a week-and-a-half or two weeks later, at
which time, (surprise!) the part still has not arrived so they
re-re-schedule another two weeks out (even if the part arrives the next day)
and since that part was not the problem in the first place, they pick the
next easiest part to replace and start the whole cycle all over again, and
again, and again, and again. . . . Meanwhile, no washer, no oven, no
holiday goodies, no sense of hope! Lots of worthless platitudes and
apologies, but no service, no help, and certainly no real effort to be of
any assistance. Calls to Chicago head office result in more "Take it or
leave it" mentality. It is worth observing, they were not as apathetic about
collecting their MA fees, up front!

Anyway, thank you all for all your wonderful advice, references, and solid
opinions. I can see this is a great group and I hope I can return the favor
in the future.

Sincerely,
Bob Giel,
Los Angeles, California

Bob Giel wrote:

> I do not understand how the age or type of oven would have anything to do

I was just wondering.

I replace the oven in the house we bought (3 years ago).
The temp would wander while it was on.
350 degrees would end up at 400 or higher whenever it felt like it.

A month after we moved in, we bought a new stove. Then we remodeled the
kitchen. Timing was not good.

> with the question of acceptable temperature ranges.


Has anyone found information about temperature in convection ovens ?



donald