Repairing a convection oven
 

Yep, the old type of oven that actually BAKES things. My folks have a
20+-year-old oven (perhaps 30+ years) that has suddenly been running much
hotter than the dial setting. After Mom and Dad each individually murdered
an angel food cake (believe me, all the icing in the world won't disguise a
manhole cover), Dad finally figured out that the oven has suddenly started
running about 150 degrees higher than the dial setting. He thinks the
thermostat is out of whack.

Replacing the entire oven is not an option, as it's built into bricks in the
kitchen and is a size that is no longer standard and a new oven can't fit
without a lot of expensive remodeling.

Dad is looking for make, model number, and perhaps part number for the
thermostat, and I promised I'd look on the Internet for help. (He's got the
manual somewhere.) Is there a site anyone can recommend for obsolete
convection oven parts? (I think Dad said the original manufacturer went out
of business long ago.)

And is "bad thermostat" a good diagnosis? I'm pretty good at fixing TV sets
and stereos, but Dad has far more experience with appliances than I do. Any
and all good advice would be greatly appreciated.

Many thanks, and happy holidays!

Matt J. McCullar, KJ5BA
Arlington, TX

"Matt J. McCullar" writes:

Yep, the old type of oven that actually BAKES things. My folks have a
20+-year-old oven (perhaps 30+ years) that has suddenly been running much
hotter than the dial setting. After Mom and Dad each individually murdered
an angel food cake (believe me, all the icing in the world won't disguise a
manhole cover), Dad finally figured out that the oven has suddenly started
running about 150 degrees higher than the dial setting. He thinks the
thermostat is out of whack.

Replacing the entire oven is not an option, as it's built into bricks in the
kitchen and is a size that is no longer standard and a new oven can't fit
without a lot of expensive remodeling.

Dad is looking for make, model number, and perhaps part number for the
thermostat, and I promised I'd look on the Internet for help. (He's got the
manual somewhere.) Is there a site anyone can recommend for obsolete
convection oven parts? (I think Dad said the original manufacturer went out
of business long ago.)

And is "bad thermostat" a good diagnosis? I'm pretty good at fixing TV sets
and stereos, but Dad has far more experience with appliances than I do. Any
and all good advice would be greatly appreciated.

Many thanks, and happy holidays!

Is it really 150 degrees hotter at any setting, or always on? That would be
a more likely failure mode for a thermostat.

There should be a wiring diagram or if not, it should be easy enough to
figure out. However, finding a replacement part for a 20 year old oven
might be a problem, especially from a defunct manufacturer. Hopefully,
a substitute will be available.

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"Matt J. McCullar" wrote in message
m...
| Yep, the old type of oven that actually BAKES things. My folks have a
| 20+-year-old oven (perhaps 30+ years) that has suddenly been running much
....
| Dad is looking for make, model number, and perhaps part number for the
| thermostat, and I promised I'd look on the Internet for help. (He's got
the
| manual somewhere.) Is there a site anyone can recommend for obsolete
| convection oven parts?

Check with an appliance parts place. ISTR that they have 'universal' parts
which can be converted to fit many models.

| And is "bad thermostat" a good diagnosis?

It's the first thing to try. Hard to imagine any other possibility.

N

And is "bad thermostat" a good diagnosis?

Matt-

I suggest you take the make and model number to a place that sells appliance
parts. They should have microfilm of parts breakdowns for most appliances,
sometimes including wiring diagrams.

A thermostat is the most likely cause. However, if your oven uses an
electronic circuit, it may have a temperature sensor, possibly a thermistor.
Temperature control could be accomplished by switching triacs that connect the
heating elements.

Whether it uses a thermostat or a thermistor, the sensor could have been moved
to a place where it isn't exposed to the hot airflow. There might also be some
debris blocking airflow in the area of the sensor.

Fred

Matt J. McCullar wrote:

Yep, the old type of oven that actually BAKES things. My folks have a
20+-year-old oven (perhaps 30+ years) that has suddenly been running much
hotter than the dial setting. After Mom and Dad each individually murdered
an angel food cake (believe me, all the icing in the world won't disguise a
manhole cover), Dad finally figured out that the oven has suddenly started
running about 150 degrees higher than the dial setting. He thinks the
thermostat is out of whack.

Replacing the entire oven is not an option, as it's built into bricks in the
kitchen and is a size that is no longer standard and a new oven can't fit
without a lot of expensive remodeling.

Dad is looking for make, model number, and perhaps part number for the
thermostat, and I promised I'd look on the Internet for help. (He's got the
manual somewhere.) Is there a site anyone can recommend for obsolete
convection oven parts? (I think Dad said the original manufacturer went out
of business long ago.)

And is "bad thermostat" a good diagnosis? I'm pretty good at fixing TV sets
and stereos, but Dad has far more experience with appliances than I do. Any
and all good advice would be greatly appreciated.

Many thanks, and happy holidays!

Matt J. McCullar, KJ5BA
Arlington, TX



more than likely its the thermostat.
if its that old it could be a mercury capillary type or it
could be a bi-medle thermostrip type/

you can most likely find a generic replacement if its the knob
t

"Matt J. McCullar" skrev i en meddelelse
m...

Dad is looking for make, model number, and perhaps part number for the
thermostat, and I promised I'd look on the Internet for help.

It's often easier to go to a "appliance spareparts store" with the Maker &
Model details - they will know which parts you need, if they are available
and whether the manufacturer has had some problems with that product: My old
Electrolux dishwasher needed three PCB's and some special cable-glands in an
"upgrade kit" to fix a problem with *one* PCB Burning when the dishwasher
overflowed.

On Tue, 28 Dec 2004 01:09:45 GMT "Matt J. McCullar"
wrote:

Yep, the old type of oven that actually BAKES things. My folks have a
20+-year-old oven (perhaps 30+ years) that has suddenly been running much
hotter than the dial setting. After Mom and Dad each individually murdered
an angel food cake (believe me, all the icing in the world won't disguise a
manhole cover), Dad finally figured out that the oven has suddenly started
running about 150 degrees higher than the dial setting. He thinks the
thermostat is out of whack.

I don't know what else it could be other than the oven control (which
includes the thermostat.) I replaced mine about 10 years ago when the
unique little "relay" died. The cost at that time was about $70 and I
got the replacement from an appliance service center. That price
includes the control, the sensing bulb, and the capillary tube that
connects the two.

BTW, for most of these controls, if you pull the knob off, you'll find
that the shaft is hollow and there is a screw down there that you can
turn to calibrate the thermostat. I don't remember enough about them
to know whether it's possible for them to suddenly become grossly
uncalibrated, but that seems unlikely

In my case I had the original Sears manual with the parts list, so
getting the right part was just a matter of calling someone who could
cross reference it.

My experience with these is that almost all of them are made by Robert
Shaw. (I think that's the right name....) It's possible that a big
appliance service store might have several types which they stock, so
you could take yours in and match it. I suspect that they are actually
rather generic, but a make and model would probably be reassuring.

Check your yellow pages under Appliances, repair, or Appliances,
parts.

-
-----------------------------------------------
Jim Adney
Madison, WI 53711 USA
-----------------------------------------------

"Jim Adney" wrote in message
...

....
| BTW, for most of these controls, if you pull the knob off, you'll find
| that the shaft is hollow and there is a screw down there that you can
| turn to calibrate the thermostat. I don't remember enough about them
| to know whether it's possible for them to suddenly become grossly
| uncalibrated, but that seems unlikely

Very possible BUT, if that happens and you open the control you will usually
find that the silver has migrated from one of the contact points to the
other making a 'hill' on one and a 'crater' in the other and making the
contacts lock together. In that case, get a diamond (important) nail file
from the dollar store and file down the peak to keep it going a while
longer. That'll give you time to locate a new part.

| In my case I had the original Sears manual with the parts list, so
| getting the right part was just a matter of calling someone who could
| cross reference it.
|
| My experience with these is that almost all of them are made by Robert
| Shaw. (I think that's the right name....)

"Robertshaw", now part of Invensys.

| It's possible that a big
| appliance service store might have several types which they stock, so
| you could take yours in and match it. I suspect that they are actually
| rather generic, but a make and model would probably be reassuring.

Google found about 14,700 for (universal oven thermostat). One might be
useful!

N

Yowsa, what a gold mine of useful information!!!! Many thanks, everyone!!!

Dad found the manual but it doesn't include the entire model number (the
oven was made by Roper), so he'll pull out the oven to see if he can find
the sticker with the whole model number on it and we can go from there.

Much appreciate the help!!! Dad says thanks very much, too!

Matt J. McCullar
Arlington, TX

On Tue, 28 Dec 2004 01:09:45 GMT, Matt J. McCullar wrote:
Yep, the old type of oven that actually BAKES things. My folks have a
20+-year-old oven (perhaps 30+ years) that has suddenly been running much
hotter than the dial setting. After Mom and Dad each individually murdered
an angel food cake (believe me, all the icing in the world won't disguise a
manhole cover), Dad finally figured out that the oven has suddenly started
running about 150 degrees higher than the dial setting. He thinks the
thermostat is out of whack.

The oven in my college apartment had this problem. Worked fine, just ran
about 150 deg. F hotter than whatever the thermostat dial was set at. A
cheap oven thermometer solved the problem.

Dad is looking for make, model number, and perhaps part number for the
thermostat, and I promised I'd look on the Internet for help. (He's got the
manual somewhere.) Is there a site anyone can recommend for obsolete
convection oven parts? (I think Dad said the original manufacturer went out
of business long ago.)

If you can get the old one out, you might want to try going somewhere
like Johnstone Supply (http://www.johnstonesupply.com/main/selectstate.asp)
with it to see if they can either match it, or cross reference it to
something.

And is "bad thermostat" a good diagnosis?

Could be. Spend $5 and get an oven thermometer to find out for sure.


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