I’m a tightwad. Few who know me would disagree. So it kind of irritates me that I have to put my truck on a block heater in the winter. I measured the heater a few years back with a Kill-A-Watt meter:
As I recall it was using 1800W and it ran as long as it was plugged in – there is no thermostat. That’s a lot of energy if I just leave it plugged in all the time.
I quickly learned that many people would put the block heater on a timer and start heating the block just several hours before the morning commute. I did the same thing using my trusty Intermatic Timer:
I programmed the timer to turn on at 5AM and off at 10AM. This system worked pretty well, but it still bugged me that the heater would periodically run when it was kind of warm and the block heater really didn’t need to fire up at all.
So I found this 115v thermostat that turns on only if the temp falls below 35 degrees:
I plug the timer into the electrical outlet, then the thermostat into the timer, and finally the truck into the thermostat. That creates a logical and:
if (time >= 5AM and <= 10AM) and temp <=35 then HEAT MY BLOCK!
Total cost of equipment is $25. I never tried to calculate the payback, but given it is consuming 1800W, I would expect it to be pretty quick.