Unknown Device comes on at night

I have a mystery device that comes on frequently. Pretty much throughout the night. Never during the day. Average time on 3s. Average times on per month is over 300. Does anyone have any idea what it could be? I’m attaching some pictures. Thanks for any help you can give me!

how big is the spike? For a human, that’s a very helpful clue. I’ll guess, around 1300-1400w?

If I were a betting man, I would bet a coffee maker that’s keeping the water hot. If not coffee maker, it’s something heating at that wattage, and the quick spike implies it’s “topping up” the temp.

Thanks! It’s around 1800w. I know it’s not the coffee maker because it is off. When it was identified it said 87% of the Sense community identified it as a furnace. That doesn’t make sense to me. Thanks for your response

Really odd that this is an “at night” only device. Are you pretty sure? Could it be getting lost in the much busier daytime traces?

Other than that, think of any devices that are only on at night…either manually or on a timer. This could also be a result of something you “turn off” (with a much different pattern from the on state during the day) each evening and it goes into “standby” and you turn it back on in the AM. For example, one of our Keurig’s has a very spiky (not too different than your images) power draw when “turned off”, but a quite different draw while “turned on”. You could check that by un-plugging, which for MANY devices is quite different than “turned off”.

1800w for the spike itself, or the house is drawing a total of 1800w when it spikes? if it’s truly 1800, then1800 is more than 15A, so you just narrowed it down to probably fewer than 10 devices in the home, and unless you have a few 20A 120v circuits, you should be able to narrow it down even sooner.

I would have guessed a floor heater with 1800w, but resistive coils don’t generally spike so steeply like that, but immersion heaters can. Any Instant hot water heaters found in your home (small, under the sink local HW) ? They will run 24/7

Great idea. Our keurig is off but still plugged in. I will unplug tonight. Strange but this starts cycling around 9-10pm and goes until around 5am

This is Music to the Sense engineers’ ears. This is why we ALL buy Sense. I know (hope) product management has some decent number on the percentage of Sense owners that “find” such a gremlin in their home after installing Sense. For me, it was power-saving laser printers that weren’t set to power-saving mode.

The spike to 1800W does means approx 15 amp@120 or 7.5amp@240 depending on what the device is. Would need to be running on a 20 amp 120v breaker to be to code if it is a 120v device. What type of heating solutions do you have in your home and are they running at night currently?

I’m trying to think of things that would run more at night or exclusively at night. Most Water Softeners these days will do the rinse and regen cycle at night, but that should only be valves opening and closing so I wouldn’t expect 15amps @120v and I’m not aware of any 240V water softeners.

We have AC units on both floors of the house and a heat pump in the basement. Because I get a lot of power free at night I usually overcool the basement a little with the heat pump. Night schedule starts at midnight and ends at 6am. I mentally disregarded that possibility because I didn’t think 3sec spikes would be due to the heat pump. Perhaps I’m wrong about that. I may bring on cooling today and see if I get any notifications. Looking at the device power meter it does show very short spikes of around 1800w. Last night it started at 8pm and ended at 2am. The night before it started at 8pm and ended at 3am.

Sounds thermostat driven - maybe heating strips for your heat pump?

That was my thought also, but the timing of the spikes and the thermostat settings are off by many hours. Definitely a head scratcher, but one thing is for sure. This is either triggered by something you do regularly every night or it’s on a timer. Second thought is that it’s likely on a 240v circuit…it’s a bit much for a 120v 15a circuit.

Right. As @jstewart0131 mentioned, just look for the 20A 120v or 240 circuits. I would guess you have fewer than five in the house, and probably can eliminate half of them with common sense. Then pop one of them tonight, and the remaining ones each night thereafter until you nail it.

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I’m not sure why the spike is happening but I know what is causing it. Yesterday I had the to A/C units and the heat pump turned off. Later that evening I turned on the main floor A/C unit. The fan turned on because it was warm. Almost immediately I got an alert that this device turned on then off. It seemed to happen every time the fan cycled on. Always went on and then off. Not sure of the purpose but at least I can confidently associated it with the main floor A/C unit. Thanks for everyones help!

Sounds like you’ve confirmed this was your Blower Fan in your AC @whalleye ?

Why would it go on and immediately off? The fan turns on a runs until it hits set point. Is it seeing the initial spike to turn the fan on but not the power needed to keep it running?

From your screenshots, it looks like Sense is detecting the start-up of the motor. It could be that it’s not detecting the full cycle of the blower fan, or that this is a different component of your A/C that also uses a motor.

Thanks. I just named it “HVAC”. If it ever picks up other parts I will just combine them