On Wed, 11 Nov 2009 17:10:31 -0800, "Ivan Vegvary"
wrote:

Have had this popcorn machine (theater type, medium size) for about 15 years
now (got it used). Unable to make a second batch of popcorn.
First batch: turn on the heater, add oil, add popcorn, wait and get about
99% to pop.
Second batch: Dump first batch, (heater switch still on) immediately add
oil and corn, wait and get ONLY about 30% to pop.
Third batch: Same as second.

Machine consists of cast aluminum pot, disc type heater (electric) bolted to
the bottom, an in-line thermostat about the size of a pack of chewing gum.
Manufacturer very helpful, we're on our third thermostat. No difference.

Question: What would make a heating element (solid disc, about 5 in.
diameter) act intermittent. It is very similar to the heating coils on an
electric stove. I would think if it comes up to temperature once, it should
be alright. There are no moving parts within the heating element. It is
probably simply just a giant resistor.
The vendor is out of ideas short of selling me a new heating element
(expensive, but I'll buy one if indicated). In his 30 years of experience
all he has sold was thermostats, or, heating elements when they were 'open'
and wouldn't heat at all.

Any and all ideas appreciated. I loan this popper out to charities all the
time and therefore need it.

Ivan Vegvary

I'd suspect the safety thermostat inside the pot, or it's mounting -
it might be missing a washer under the sense element mounting screw,
or the sensor element bulb is loose against the inside of the popping
pot.

It warms up properly to run the first batch and the heater will stay
on pretty much constantly, and when it nears completion and all the
oil and kernels go away the thermostat cuts out - that would be
normal.

But when you swab out the pot, flip it up and fill it again with
cool oil and fresh corn the thermostat should reset and heat the pot
to full blast again - and it won't reset.

Don't discount that it could be an inherent poor design of the
thermostats - I'd want to check the spec sheets. I have seen makers
cheap out and save a dime by using a 6A rated stat on a 6A load,
meaning "it's legal" but there is no headroom on the contacts - it
works till it's out of warranty, then it fails...

A10A rated stat will last 'forever' on a 6A load, because it has a
little headroom.

If the heating element is going intermittent it wont be "going" for
long before it's "gone" permanent open. It can arc across the break
for a dozen or three cycles, but eventually the spark gap will erode
to a hopeless condition.

Watch it with the ammeter, and study the wiring diagram for other
possible opens - If it's a removable pop pot it could also be the
receptacle where the cord on the pot plugs into the machine body.

Oh, and that cord to the pot could be going bad, too - it flexes
every time you dump the pot, and wiggles from the stir motor...

It might have chrome flex armor on the outside, but inside you'll
find either SO Cord, HPN heater cord or (best) three strands of the
Silicone and Fiberglass "Nickel Hinge Wire". And they will go longer
when going bad before they flat out fail.

-- Bruce --