If it’s a 240 device it will pull exactly the same from each leg. If it’s using 1500 watts then half comes from each side
Good sleuthing - it does look like a 1500W 240V device.
I don’t know if some dryers still work this way but I had one that the heating elements would run if the timer had not run it’s full cycle. If you opened the door and left it open, it would continue to heat until the full cycle was finished. It finally burned one of the elements out but took a very long time.
If the usage is spread across two mains, it’s highly likely it’s a 220 v device. The only other possibility is two 110v devices synchronized exactly. While, as an engineer I could figure out how to do that, I can’t think of any reason I’d want to and I know of no such things in the home environment.
Since you turned off the 220v circuits, you don’t by any chance have a sub-panel hidden someplace that drives what looks like a 1500 watt heating device on a timer??? Power and heating for an outbuilding, perhaps?
Samwooly1, I had turned all the other 220/240 breakers off , including the dryer breaker. What I might do is move the sense device to a different 220/240 breaker and then shut off the current breaker being used for the sense device.
Andy, the house is 50+ years old and I have only been in it for 25 years. It is entirely possible there is a subpanel that I don’t know about, I’ll keep looking.
I would not move where sense is connected, I’m sure you will lose almost everything.
If you cross legs it will confuse sense and any work in the breaker panel has caused me trouble. I exchanged a single pole breaker that had nothing to do with sense and it has never recovered.
Andy, I don’t think it is on a timer because as the outside temperature gets warmer the time between power up increases from 30 minutes to over an hour … so I think there must be a temperature sensor involved somewhere.
Count your 240 breakers and see if it lines up with known 240 devices.
I have
Dryer
Stove/oven
Heat pump
Air handler
Heat strips
Water heater (sense)
If you have an extra you will know if there is something you don’t know about or a feeder for a sub panel
I have a dryer, 2 stoves, shower steamer, and an a/c unit which matches the number of 240 breakers.
Does your shower steamer have a tank it keeps hot?
no tank on the steamer.
Is it possible that multiple devices could be on a single 240 breaker?
Are any of the breakers larger than 50 amps? That would indicate the possibility of a sub panel that could ha e more breakers in it.
It’s possible a breaker is double tapped but it’s not within code. Or wires could be tied together away from the breaker with a single “pigtail” wire leading to the breaker. Possibly not likely.
I’ve seen so many things in this house that are not up to code, It would not surprise me.
When I’m having trouble identifying what I do is turn off all breakers except the ones for sense and internet. I then turn on one at a time until I find it. I turn one on and if isn’t the one, I turn it off then turn the next on.
no breakers larger than 50
You do have a tough one. On your single pole 120 breakers, do any have a white wire feeding into them? If you can see it that is
samwooly1 , I may need to resort to shutting down all breakers except sense and internet, wife won’t be happy 
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