Mystery motor, run times early morning and evening [edit: motor, not heat]

I have a mystery heat device that consumes 142 watts and runs for 4 minutes at a time, clustered in the 5am to 9am time period and in the evenings. It runs much less frequently 10 am to 3 pm and 10pm to 3 am. Our heating system is a propane boiler and I’ve already identified as a different device the red hot heating element that runs for 20 seconds to ignite the propane each time the boiler starts. I have also ruled out my Insinkerator under counter instant hot water tap by uplugging it when the mystery heat is on. I’ve considered the heating elements that warm the battery and the oil filter of my Generac standby generator but not having the device on during the coldest part of night suggests against this. Any suggestions from the community or developers as to what this might be?


That’s a heating element? At least the start of it looks very much like a motor/compressor - something that briefly has a large current influx to overcome a locked rotor.

Could this be a compound device, including a motor or a piece of electronics that needs all that start-up current?

Heating elements don’t normally behave like that.

I think Sense is flagging it as heat because of the type of variable profile after the initial inrush.

Do you have a local outside temperature history source that’s credible for your location, which you could compare with the rate of use of this? 5 am to 9 am sounds credible, allowing for the generator to cold soak overnight, but as you note some of the rest of that doesn’t fit as well, however in our location, the daily temperature variation can be very odd in the winter and not correlate obviously with normal day / night cycles. (Rockies foothills, 7000ft tucked in at the end of a valley/

Your last picture looks exactly like what I think my refrigerator defrost looks like.

Unless something is going on with your fridge, it shouldn’t be running more than once or twice a day.

I didn’t think that it was heat, either, with the initial rush. Frankly I’m stumped. My fridge’s sensor to trigger its defrost cycle has been non-functional for a couple of years. In humid weather I need to periodically trigger it manually by flicking the door switch rapidly a few times or else the evaporator will frost up and block airflow. So it’s not likely to be that.

My fridge and a wine fridge have already been found as devices - I guess the regular compressor cycle. My upright freezer has not yet been identified.

{edit to add} Perhaps it’s one of the many circulators in my heating system, maybe the one that supplies the domestic hot water tank. That would account for it not running when there’s little activity in the home. The only remaining puzzler with this is the short (4 min) run time. {end edit}

But thank you to all of you for kindly trying to help identify this device.

That signature looks similar to one of my circulating pumps and interesting enough, it runs almost 4 minutes.
Just an FYI.

I agree with Fred. It also looks like another device that seems to be a group of circulators that operate at the same time. I just realized that I could change the Sense category from “mystery heat” to “mystery motor” so I did so.

I have the same type of mystery device. It used 161 watts and goes on every 2 hours for 4 minutes. It only goes on during the daytime. I can’t figure out what it is.

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