once again into the breach....

[phil]

we always left a light bulb on in the pump house, and that was enough in the little room to keep it not frozen until the light bulb burned out and that took out the pump.
The moral is that duplication is a good thing. after that there were always two light bulbs glowing in there.

my boss had a sophisticated sewage pump, because his field is elevated. the electrician that installed it put in a sensing alarm so if the sewage didn't get pumped it would sound the alarm. The problem he overlooked was that they were both on the same circuit so the breaker blew, the alarm did not sound and he found himself needing to dig it out.

Perhaps the heater could have a relay wired in such way that it could trigger an alarm if it stops drawing power. ( a holding circuit). If the heater's power circuit is lost then it could close some relay contacts and sound an alarm. this can probably be done with a fairly simple wiring arrangement. power for the alarm could perhaps be from another circuit that is used often or a battery backup. when there is power draw the relay stays pulled in and keeps the relay on and the power on to the heater, when that power is lost then the relay looses power and a second set of contacts is used to turn on the alarm in that non-energized state of the relay. That might not be a clear description but it could work something like that..
you can also get sensors that detect the power draw in a wire from inductance. they are used for things like to turn on a dust vac system in conjunction with a machine being in operation, they just attach to the power wire and sense power use. - a sensor like that might also work. as long as the heater is drawing power you know it's working. If it stops using power it could trigger some sort of alarm.

Lily Thanks for the link, I'll review the video. Sounds interesting!
Phil