So, I extracted the thermal cut-out from the infamously unusable Kambrook KFH200 fan heater, and it's an AuOne
AUT-75 (no datasheet, unfortunately). Though, if the trip temperature is 75°C as that number suggests, then that's the same setting as in the KFH660 – and the AUT series is of a design with much
lower self-heating than the Klixon (although the airflow from the fan would reduce the resultant temperature rise considerably).
![Huh :huh:](./images/smilies/huh.gif)
Either it's not a 75°C cut-out, something wacky is going on with the tolerances (although that's specified as either the same ±5°C as the Klixon, or alternatively ±7°C), or the difference is due to the internal design of the heater. I do have a heat gun with electronic temperature control between 50°C and 630°C in 10°C increments (Bosch PHG 630 DCE), but I have doubts about its accuracy at the low end of the range; regardless, it did trip when I raised the temperature from 70°C to 80°C. A similar cut-out (from a different manufacturer, but otherwise looking almost identical) with a known temperature setting of 85±5°C (in another, el-cheapo – but still working – 2.0kW fan heater) reacted when raising the air temperature from 90°C to 100°C, so it seems to not be too far off.
I'm still not sure of the precise flaw, but in case it's relevant, the KFH660 has a sort of tube (integral to the casing) mostly enclosing the fan and heater proper; whereas the KFH200 and that cheapo unit are both more open (with only the front half – or more like third – of the tube).
Whatever the case, the KFH660 stays on just fine, while the KFH200 didn't (even when I tried it
outdoors!). For what it's worth, the KFH200 wasn't the only fan heater with a thermal cut-out set too low…
Information is far more fragile than the HDDs it's stored on. Being an afterthought is no excuse for a bad product.
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