After I installed Sense, I saw something on the Power Meter using electric every few minutes. The same signature. All day long. 24/7. It was not using a lot of power but the spikes where there and consistent.
After investigating by going around the house and turning things off, we finally found it. It was our Whirlpool water cooler and specifically, it was the heater for the hot water.
I bought a smart plug and initially put the water cooler on a schedule turning it off for about 12 hours/day. But because the water cooler was either on or off, and we use the cold water all day and evening, this was not working. Now we just turn the hot water off in the morning and turn it back on the following morning for my wife’s hot chocolate fix. I still have the whole unit on the smart plug so it only runs about 12 hours/day, however.