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Popcorn machine (metal content)

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

Reply to
Ivan Vegvary
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Do you have a thermocouple you can measure the temperature with? Maybe a cheap digital multimeter + thermocouple probe.

Just a wild idea - how is the heating element mounted - is there anyway that it could flex/bow away from the pot as it heats up?

Reply to
Nik Rim

No, it's unusual but it can happen. You need to hang a clamp AC ammeter on one line and watch the amps. Another test (tricky) is to short the thermostat and see if you can run two batches -- but watch out for overheating!

Reply to
N Morrison

I suspect the over heat switch is set and you have a warming value or the warm value of the switch has resistance.

I have some thermal switches that have coils that heat in series and once hot it shorts out the coil. Resistive wire that heats the bi-metal.

Try putting an ice cube in the bucket - then towel it out. It might be cold enough to reset the contact set(s).

Might be the contact set is getting pitted and takes a full cool to really press hard.

Mart> Have had this popcorn machine (theater type, medium size) for about 15

Reply to
Martin H. Eastburn

Reply to
RoyJ

bad heater or connections? It's possible the element has a crack or something like that.

There is stress on the element itself as it heats and cools off.

Reply to
Cydrome Leader

To all the above. I have an ammeter and will monitor the readings throughout the first and second batches of popcorn. At the conclusion I will report back and you guys tell me how to interpret the results.

Thanks, Ivan Vegvary

Reply to
Ivan Vegvary

I would also get an IR thermometer and monitor the temperature.

Reply to
Bill McKee

Ivan, My guess is the pot itself. I believe you are losing the heat couple between the element and the pot due to distortion (warping) Steve

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Reply to
Steve Lusardi

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.

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Reply to
Bruce L. Bergman

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