Appliances #1: Real-world fault tolerance

A few weeks ago my sister was visiting and offered to make us dinner one night.  She was broiling chicken when, halfway through cooking, the oven suddenly stopped working.  Even after letting the oven sit idle overnight and cycling the power, the problem remained. 

The symptom was that the heating elements were not getting hot, even when the electronic controls (which appeared to be working fine) indicated that they should be on.  It was affecting both the upper and lower elements, even though the lower element was not in use when the oven stopped working.

When my wife called Dacor to get assistance, they immediately knew the cause.  The broiler had been on with the oven door open, which is the traditional way to broil.  As explained here:

Broiler temperatures can be in excess of 500 F. At these high temperatures, if the door is closed when you are broiling and you open the door, the sudden rush of oxygen could cause flare-ups and you could be burned.

On the other hand, our oven’s owner’s manual explicitly and repeatedly says, "Broiling is performed with the door closed."

So what’s the explanation?  In order to protect the electronic control panel, the oven has a breaker that causes it to shut down automatically when it detects excessive heat near the panel, the kind that might be generated by, say, broiling with the door open.  The downside is that Dacor won’t tell the customer how to reset it, because they want a qualified technician to verify that the electronics were not damaged by the heat.

In our case there was in fact no damage, so while we were out the cost of the service call, we didn’t have to spring for expensive replacement parts.

Why doesn’t the aforementioned flare-up problem affect this oven?  I’m not sure, though my hypothesis is that because the oven has its own automatic, thermostatically-controlled exhaust fan, perhaps it’s not subject to such problems.

What’s interesting about this episode is that the manufacturer has put a fail-safe into the oven that’s necessitated entirely by people’s traditional behavior and their failure to read manuals.  You just know that the first generation of these ovens were plagued with expensive repairs for exactly this reason, and in all likelihood were blamed on "unreliable electronics."

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2 responses to “Appliances #1: Real-world fault tolerance

  1. Interestingly enough, one of the other issues with the Dacor ovens is their self cleaning cycle – it has can melt the thermometer on the oven – we went though about 6 thermometers before they finally figured this out and got a fix for us.

  2. the rest button is the red botton behid the grate above each oven. It is in the center sitting on a black (usually dusty) cube – 1 inch by 1 inch.

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