Help Identifying Mystery Device

My Sense has been installed just more than a week. I’m having trouble identifying one of my detected devices that showed up pretty early. The community names feature indicates that 98% of users call similar devices either “pump” or “sump pump.” The problem is that I don’t have either one of these.

This mystery device seems to run roughly every 50 minutes or so but only for 2 or 3 seconds. This cycle repeats day and night, with no apparent variation. Average wattage is 568w but varies between 500 and 700.

Any ideas?

Thanks for helping out!

Do you have a Keurig coffee. Maker or similar that is never turned off?

Do you have an Icemaker in your fridge? Could it be the heating element that comes on from time to time to release the ice before it is flipped into the ice bin?

No Keurig coffee maker… just the regular kind that heats when you turn it on and that’s it.

Yes, we do have an ice maker, but it typically only runs one or two cycles after we’ve used it. Then it sits idle until the next use. This load cycles predictably and appears to be independent of our ice use.

I have thought it could be something with the automatic defrost cycle of one of our fridges/freezers, but that’s just speculation right now.

It’s unlikely to be a properly-functioning defrost cycle … the pulse is too short and too frequent. I believe most fridge/freezer defrost cycles default to once every 24 hours and they run for a lot longer (my fridge’s is 20 minutes).

If you can post a waveform from the Device and overall Power Meters it might help determine what it is. Sounds like it has a startup spike if Sense is thinking it’s a “pump”.

That would be unlikely, because defrost heat cycles typically last minutes, not seconds. Also, it’s curious that Sense thinks this is a motor of some kind, and the most likely candidates (as you’ve seen from the thread) are heating elements.

Can you provide an image of the power, which may help the folks with ideas for you?

Yes, it could be that Sense has detected only a portion of the waveform (it does that a lot), and thinks it looks like a motor start-up surge. Images are always helpful.

Trend Screenshots are below. The first is just the “pump” while the second shows everything. There is an increase in overall wattage (~60 watts) shown in the second image. This is consistent with other times when this device is running, although the wattage increase has some variability with at least one instance being around 120 watts. Now I’m suspecting that this may be one of our fridge/freezers (we have 5 of various types and sizes) but the run frequency is just too regular… always between 50 and 55 minutes between starts. See the third screenshot for the cycles.

Could this be an Icemaker and the water being pumped in for a new batch of ice?


  • The regular ~50min cycle would point strongly to an automatic function and rule out anything user-related. e.g. varying ice usage would throw the cycle off.

  • The flattened Device Sense-detected waveform would suggest that you aren’t seeing, in the Device waveform, likely significant variation over those 2 seconds … i.e. most likely there’s a spike in the there somewhere. 568w average is in the realm for a pump and Sense’s determination is based on analysis you aren’t seeing in the waveform. The overall Power meter does look more pump-like (initial spike).

  • What is your water supply and HOT water situation? Swimming pool?

  • What is your HVAC situation? (compressors/pumps/fans could all result in signatures you are seeing, remembering that the waveform most likely does not represent an entire device, or even part of a single device for that matter)

  • A zoomed-in view of the overall Power Meter spike could be more revealing.

Another question: Do you have a de-humidifier?

@dylan.christopherson just posted some (likely) relevant info for you here:

See if its the condensation pump connected to your central air conditioning De Humidifier. Mine runs off and on when my central air is on for no more than about 3 seconds each time. Took me a little time to figure that one out too.

I’m finding it very tough to identify many of my loads. My commercial freezer has 3 motors, one for the compressor, one for the evaporator fan, and the condenser fan. I have loads called AC’s and some called motors. And it’s hard to tell if the compressor is on when the condenser fan is running (it makes all the noise). It would be helpful if we could isolate the two hot legs on a graph. 2 or 3 seconds is real short duration. How about a defrost cycle on a fridge? unplug it for 2 hours and see if the load disappears.
good luck

@ixu The weather here is perfect right now and HVAC is off… no fan, no AC, nothing. When running, condensate drains by gravity.

City water supply. I do have a softener and an irrigation system that runs occasionally in the early morning hours. No pool. Water heater is gas with combustion blower that uses around 40w when running.

No dehumidifier.

First image below shows what appears to be a full 15 minute cycle for this device. A zoomed in look at the start portion is also shown.


I would respectfully request that you start your own thread. You are more likely to get good feedback that way, and this thread regarding my “mystery motor” will be easier to follow.

I have had a similar issue and am more than willing to share my experience, but not in this thread.


I hadn’t really considered that it may be one of the fans in my refrigerator or freezer. Because the cycle is so repeatable I should be able to test that theory fairly quickly and easily. Thanks for the tip.

@2uskiwis I’m assuming there is no pump that supplies water to the ice maker. It is very likely that this is just a solenoid valve that opens and allows water to flow into the ice tray, with the pressure of the municipal system creating the flow. I’ve not torn my fridge apart to prove this, but this is exactly how the fill valve on a washing machine works, for example. And, as I’ve mentioned and others have affirmed, the run cycles are unrelated to ice use.

It will be interesting to see if Sense’s “pump” designation was off … at this point it starts to feel like Sense is perhaps beating humans on certain aspects of detection. Witness the machinations herein with us humans trying to figure things out!

I’m gonna place my 2 cents on Sense and ask (retroactively, for the humans in the house?): sewer pump?

I’m going to pile on the same bandwagon. The profile Sense is spotting looks a sewage / sump unit that we use for a couple applications across a couple properties. 2 sec on at about 750W. We use the pump in one place for a waste sump for a sink in our barbecue island that is lower than the sewer line. The other is in use in a low spot in our yard where an underground stream flows through the hillside. The second application come on sporadically throughout the day as water fills the sump bucket. But that’s ignoring the long tail. Unfortunately, both of those aren’t at my primary residence where I have a Sense.

One other option - water softener regen gone gonzo. There’s a pump in there, but it’s only supposed to go on every 12,000 gals.