Name that device


I have no clue what this is. It shows up as Device 1. What’s strange is it appears to turn on and off when I am not home. Ideas?


Some sort of low wattage heating device that comes on periodically? There’s some device associated with my air handler unit that has a similar pattern. It disappeared when I shut off the breaker to the AHU.


Well, my a/c hasn’t been on today and I have hot water heating, so it’s definitely not my air handler. The average run time is 11 seconds, so it’s not on long enough for me to flip breakers.


My Ice maker in the refrigerator looks similar. Its when the water fill portion runs.


What model Fridge do you have? We don’t make much ice so I’m not sure it’s that. Why would it be happening a few times in the night when we are all sleeping?


I have a Frigidaire PLHS67EGSB1. It happens at my house at night because we use ice for the dinner meal. It will then run several cycles throughout the night to replenish the ice.



Yeah for me we haven’t used ice much lately and this device is turning on and off at all sorts of hours. We have a GE PFE27KSDCSS.


Back to HVAC, many systems run just the fan periodically to mix the air if the A/C or heat doesn’t run. Mine does that and it also has a motorized damper that opens during these spells to allow a little “fresh” outside air in. The little device that controls this defaults to once/hour which seems about like what you’re seeing. You have some gaps but I’ve found my Sense only sees this sort of thing about 75% of the time. My fan uses something like 30 watts and you’re seeing 25. So a lot of this matches. Except… my fan runs for 20 minutes at a time which is the default. It may be that your Sense is seeing either just the start-up transient or the motorized damper. Of course if you don’t have this sort of thing, that isn’t it! They are required by code in some areas, though, so I’m wondering if you do.


My heating system is hot water based and does not tie into any fans that I am aware of. It’s all connected to my boiler.


It seems to be something that’s on regularly during the day, but less so at night - is that a consistent pattern?

The pattern does seem very fridge-like, but I’m not sure what part it could be. One way to test would be to pull the fridge plug for a few hours during the day when you expect whatever it is to be cycling :slight_smile:


Here is the last 24 hours…


I’d bet it is cycling all day and night and the Sense simply misses some of the events. The folks suggesting a fridge running may be right. Mine runs on close to a one hour frequency like that. To be such short pulses, though, it would have to be only catching the start transient. I have that issue with my dishwasher drain pump. I get 1-3 seconds at the strart of each run and that’s it. Could you zoom in on one or a few of the spikes and post that?




Agreed. My water heater recently went from regularly identified to only being identified during the evening warm-up, missing the AM warm-up.

That signal also looks like a light of some sort, and it’s pretty consistently coming on every hour. A 25w light that comes on every hour at about half past…


I am now going to troubleshoot this by unplugging things. It’s happening every hour as mentioned above. I thought it might have been my wine cooler or my wife’s Cricut machine, but it’s neither.

I also don’t think it’s my Fridge as I purposely had my freezer and fridge door open while this mysterious device was on and I didn’t hear anything unusual.


Hmmm…I have one of these in my boiler room, I wonder if this is the device checking every hour to see air quality:


Thanks for the pictures. It doesn’t look like the few start-up transients I’ve had detected. Those have a fairly pronounced spike at the start then a fairly steep decrease until the Sense stops seeing it and it drops to zero. Yours is more of a square wave so it may be that the 11 seconds is the whole thing. As if I knew what I was talking about! I’m not familiar with the fan-in-a-can but a quick search makes me think it only turns on when the heat turns on. Fortunately your signal is pretty repeatable varying only a few minutes between cycles. You could always stand by it when the next cycle is about to happen to see if it does something. Better yet, put people throughout the house and make everyone be quiet at the appointed time and see what, if anything, makes noise.


I have a 2 and 4 year old. Impossible! Anyway, I’ve made progress. It’s narrowed down to my Field Controls Fan in a Can or my Weil-McLain Boiler by flipping the breaker as they both are on that. I get the alerts every hour but it’s not when the fan in the can actually kicks on as that would be obvious.


Sounds like you almost have it despite the noise. Let us know what it is when you figure it out.


What’s weird is after I flipped the breaker, the behavior changed for a little while after I turned it back on: