I am trying to determine all possible failure cases for a heating application with a peltier. Most sources I find on the internet are looking at peltiers as a way of cooling CPUs, so I have heard already that of course they act as an insulator when dead, but I am trying to find out more of the worse-case-scenario of heating effects.
It is unclear from my research whether a failed peltier or an improperly managed peltier ends up effectively being a resistive heater, and if so, is it at the wattage level of the original peltier?
I regularly have used peltiers in heating box applications currently and am trying to design a safer heat box, out of concern that a failed 100W peltier would act as a 100W heater which might create an isolated hotspot (say if the fan also failed) capable of igniting something. But my experience has not validated this theory. In my experience a failed peltier generates less/no heat compared to when it was functioning, not more. But perhaps there are multiple types of failure.
So can anyone give me a straight answer on the possible temperature/error states of a peltier? I am guessing it is something like.
- Working Peltier: maximum surface temperature on hot-side is a fixed differential over the ambient room temperature on the cold side defined by the heat pump capacity and helped along by a small amount of resistance.
- Shorted Peltier: becomes a typical resistor, at a wattage dependent on where the short occurred inside? Is this common, possible?
- Broken Connection Peltier: does nothing if the connection is broken somewhere inside.