A real-life debugging story: the stove monitor

A while back my sister and I joined forces to install a stove monitor for one of our family members.

A stove monitor is basically a sensor, plus a circuit breaker that sits between your stove/cooktop and the electrical system, along with a little program to control it. If you toss a frozen pizza in the oven and forget about it, the stove monitor will beep at you. If you don’t push the everything is OK button within 60 seconds, it will cut the electricity to the stove.

My family member isn’t much of a frozen pizza person, but they’ll turn on the wrong burner, or forget to turn off the burner when they’ve finished, so they figured a stove monitor would be a wise investment.

We installed it, and everything worked great. My family member was pleased; it beeped in all the right situations.

But then one day a couple of months later it started overreacting. Within 15 seconds of turning on a burner, it would beep and immediately cut the electricity to the unit without giving anyone a chance to hit the everything is OK button.

My family member was about to go on a 10 day trip, and I was about to stay in the apartment to take care of some things, so they let me know that something was up, and off they went.

Cooking was now a bit of a wrestling match. Turn on the burner, get a few seconds of heat, then the stove monitor would get the upper hand. I’d long-press the OK button, but a few seconds later the stove monitor would shut everything off again.

I started troubleshooting.

Apparently the combination of beeps and the color of the blinking light when it turned things off meant that the sensor was positioned incorrectly. But I hadn’t moved the sensor, and it was mounted on the wall. Very strange.

I took the sensor out of its mounting and then put it back. To no avail.

Full reset? This involved turning off the oven, going out to the electrical cabinet and cutting the electricity to the kitchen for 10 seconds, turning it back on, and listening for a pattern of beeps, and then pressing a button in a specified pattern.

Full reset gave me about 2 minutes of heat before it cut out, which was sort of better, but not really a solution.

Battery?

Nope. Changing the battery didn’t help.

I thought: Maybe the unit is faulty? I called my sister who had since installed an identical stove monitor, and she lent me her sensor. I popped it into the wall mounting.

Nope. Same problem.

Okaaaaaay. Maybe something changed the sensitivity of the sensors?

I pulled out the installation manual and figured out the pattern of button presses to decrease the sensor sensitivity.

Nope. Same problem.

I thought: Maybe I’ve got the direction wrong? Maybe saying “plus” means that it will tolerate more, not that it is more sensitive. So I went in the other direction.

But, no. Same result. And also, rereading the description I was convinced that I was right the first time, and it meant sensitivity.

I put it back to where we had it before, which had been working for weeks.

I was now starting to run out of options, and also time, because my sisters kids were coming to visit and I had to cook them dinner.

90 minutes of running back and forth to the electrical closet so I could get 2 minutes of heat later… the kids were happy and fed, but I was almost in tears.

In frustration, I dragged the whole stove out into the middle of the kitchen so I could bypass the monitor.

Bliss! I cooked, and not once did I have to run to the electrical closet.

Then, anticipating my family member’s return, I reluctantly reconnected the monitor and pulled out the manual again.

I did a full, step-by-step reinstallation, just to make sure I hadn’t missed something. I hadn’t. It still was giving me that same error: Incorrect sensor position.

Wrong sensor position. Hm. That’s not possible. Right? It can’t be. It’s in the exact same position…

I tried jiggling the sensor in its mount. The sensor didn’t jiggle.

But what did happen was that the wall moved a bit. Or, actually, not the wall. The 1980s vinyl wall covering moved. It was curling off the wall at the top near the exhaust hood. The peeling wall-paper had changed the angle of the sensor just a bit.

Incorrect sensor position, indeed.

I glued the vinyl back on the wall, and the stove monitor was happy, and so was I!

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You’d bang your head against the wall if you didn’t fear you’d disrupt the sensor.

“All your cooking are belong to us”