why do heaters always fail in the "on" position?

[gregzz4]

Originally Posted by christyf5

Came downstairs to my nano at 89.7F

This little guy saved my downstairs 36g twice. I could hear it beeping from upstairs.
Once was during a heat wave, so I bought a chiller.
Next time it went off was when the chiller stuck on and the heater couldn't keep up. Stupid chiller

This isn't first heater you've lost this year, correct ?