Mystery device solved! AC fan startup (and an error)

I had a mystery device lasting only a few seconds running pretty regularly throughout the day. Sense called it Motor 1 and was 95% sure it was a furnace.

Eventually I realized the Motor 1 was being detected immediately after each AC startup. After some investigating, I realized that it was detecting the startup of the indoor fan for my HVAC. There’s a power surge when the fan turns on, and sense was detecting the power surge as Motor 1, but when the surge ended, it was attributing the fans power to the AC. Unfortunately, once my compressor turns off sense recognizes the AC as turned off, and the energy used by the fan is then categorized under “other” for the few minutes the fan continues to run after the compressor is turned off.

If I run fan only mode, everything is detected correctly, and motor 1 will show as running for as long as I let the fan run. But I don’t really ever do that.

Problem solved! Still not perfect, but by merging the Motor 1 and AC it will accurately capture most AC usage. Of course, during the summertime when the furnace runs the fan it will show as AC power. Oh well…


Nice job solving so quickly… Many of these brain teasers go on for a while.