Portable heater when on/off is identified as my previously detected hot water dispenser

Hi, my hot water pot (dispenser) was detected first a few months back and recently when the weather started getting colder, I started using my small portable heater. But when my portable heater turns on or off Sense displayed it as my hot water pot since they both have similar wattage (650-700w). How do I train Sense to separate the two?