Sense has detected my air handler, but only sorta but not really. Does an air handler do anything besides blow air?

Disclaimer; I am a new Sense user. Sense doesn’t even have a weeks worth of data to go off yet. I mentioned in another post about Sense detecting a dishwasher when I was sure the dishwasher was not running. I have narrowed it down to what I believe is my air handler, but I’m a little confused by the data.

So first, I waited until Sense detected “dishwasher” and went and started flipping breakers off to see what made it disappear from Sense. First I tried the fridge with no luck. Then I tried breaker 1/3 which is labeled AC. Also no luck. Tried furnace, same thing. Flipped the breaker labeled “Cool Top” and it immediately disappeared from Sense. So I found the right breaker. I’m not the one that labeled these breakers so I’m not sure exactly what is meant by “cool top”, but the only thing that makes sense to me is for this to be the air handler.

But… over the course of last night, Sense would tell me the air handler turned on. It runs for 3 minutes (nearly every time Sense detects it, it runs for 3 minutes) and then turn off. Every single time it would consume about 185w during this period. The time between it turning off and then back on again seems to vary (I wish in statistics, there was an “average time off” or something like that. I have IFTTT setup to log on/offs to a Google Sheet. It looks like it ranges from anywhere from about 20 - 30 minutes to an hour. But here’s the weirdest thing, last night I had the air set to 76 like I always do. The current air temp was 76. The AC unit, nor the fan was actually turning on. Sense would alert me that the air handler turned on and I’d stand on a bar stool and feel and there would definitely be no air moving.

So I’m pretty confident that it’s the air handler using this electricity, but I’m not sure what it’s doing for 3 minutes every 20 - 30 minutes (I think the longer gaps may just be Sense missing a detection halfway) that would consume 185w. This is the model air handler I have, and just to be complete, this is the model AC I have.

Sense has likely detected one speed of a variable speed fan. With variable systems, they have steps or ramps where the fan may run on high for a few minutes and then lower the speed.

Flipping breakers can give you mixed results when identifying detections. Sense uses the signature of on/off events when the device is cycling in its normal course of functioning. When you flip a breaker, your changing that. I have used the breaker flipping with success but the forcing a shutdown is something to be aware of.


Well, this is what I thought at first, but my AC didn’t come on at all for almost a 2 hour window last night and during this time, Sense detected this device turn on for 3 minutes at least 4 times. The fan is supposed to only run when the system runs. That’s the setting I have selected in the thermostat. So if the AC never came on, the fan should not have come on. Plus, I put my hand right up to the vent and could not feel any air coming out.

I almost feel like it’s a small computer running a quick diagnostic or something.

A couple of points:

  • Sense is going to take some time to learn its new environment.
  • Clearly big energy consumers count most against your monthly bill, that air handler is quite a beast too.
  • Many breaker panel labels are either wrong or have changed since they were put in place, depending on how old your place is. You may discover some really weird commonality. But again, the big consumers are the focus initially.
  • Vampire loads running all night are devious in that their accumulated energy consumption can be surprising. TiVo, Modems. Routers, Bitcoin systems crunching data, gaming systems, etc.
  • Anyone who has Sense may be looking for something different. Shedding loads, minimizing waste, saving money are common themes, however.
  • Air treatment systems don’t respond to short changes, they have long response times, and built in hysteresis so that they don’t chatter on/off/on/off. One shouldn’t expect immediate response for changes in settings.

Sounds like you are in a newer place, possibly in the deep south. Good on you! :wink:

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Would you post a waveform screenshot so the wattage and cycles can be seen?

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Sure. The one that shows under the device or a screenshot of the meter that shows total consumption during the time it’s running?

EDIT: When looking at the power meter for a specific device, is it possible to change the time window from 24 hours? It makes everything super squished and hard to read.

When looking at an individual device power meter, use your fingers to stretch or squeeze the timeframe. This is done with two fingers. On finger will then scroll or slide to whatever you want to see, from entire history down to one minute.
It’s a basic zoom operation

I figured out how to change the scale from 24 hours. It’s not a standard pinch in/out, it’s more like a separate left/right, kinda hard to describe. Anyway, here is a 4 hour window.

Seeing this definitely makes me think it’s not the actual fan on the air handler. It uses the exact same amount of energy every time and the interval is almost exactly every 30 minutes and lasts for 3.

You can post screenshots directly into these threads. See the box with an upward arrow at the bottom right of the text editor frame? Click here and add photo. It will show the progress of the upload in a percentage format. Make sure you wait until it displays “100%” or it will get lost.

Your screenshot appears like a heating element to me. Notice in the minutes it’s on that there are dark orange vertical lines? This indicates it’s turning on and off several time in its short few minute cycle.

I don’t think it’s something turning on and off. Here’s a view of a single on cycle.

It’s hard to tell in the first screenshot but the cycle that turned on at right around 1pm appears to have lines. I could be wrong of course

It’s just because of how squished it looks in that view. If I zoom in they all look the same. I find looking at this stuff really fascinating. If I find the occurrence from last night where I turned the breaker off, I can clearly see that particular on cycle being about 45 seconds long instead of the usual 3 - 4 minutes. It’s the only cycle that’s shorter, so I’m pretty sure I got the right breaker.

Trane touts these units as being super efficient because they are “communicating”. Supposedly it constantly takes information, indoor temp, outdoor, temp, humidity, staging, time of day, run time, and fan speed and makes minute adjustments to optimize operation. It keeps run time data and reports faults to assist with troubleshooting.

So unless there is something else on this breaker, I think this is the little computer waking up and doing its thing for a few minutes. If this is the case, I wonder what I should classify it as in Sense…

There shouldn’t be anything else on that breaker. HVAC stuff is on dedicated breakers and circuits.
It’s probably one speed of the fan.
I know you said the system was off at one time when Sense showed it on. It could be the system was circulating air without running the compressor. It depends on the system design and the thermostat, it’s capabilities and settings.

I agree with @samwooly1 that it looks like a resistive heating element. Air handlers sometimes have these just like fridges do to “defrost” … but I don’t see that detail on the Trane spec. The short silent cycle would point to something like that.

186W is way too large for some internal processor wake-up imho … more likely a controller would be consuming a few constant watts.

Quiet low fan speed seems like a good guess.

There’s also the distinct possibility it’s just a phantom “device”. Do you see the corresponding 180+W pattern in the mains Power Meter? Often it’s difficult to tell but that cycle looks identifiable. Post some mains PM zoom-ins for the same period.

I haven’t seen a defrost for the air handler but there will be one for the condenser.

Oddly enough, right after my last post the “air handler” either didn’t come on or more likely, didn’t come on in a way that Sense could detect for a long time. It was off in Sense for about 14 hours. It came on again right at 11:30am and again a couple minutes ago at 12:00pm. I suspect y’all are right about this just being a specific speed of the fan or something that Sense is seeing. For the first ~ 24 hours it was detected, the consistency of it turning on every 30 minutes, at 186w, for exactly 3 minutes was very suspicious to me. But now it’s starting to show up more sporadic, so maybe Sense is just getting better at recognizing it… or maybe it is just not actually running as consistently as I thought because Sense can’t see the full picture since it is a variable speed fan.

186W is way too large for some internal processor wake-up imho … more likely a controller would be consuming a few constant watts.

I completely agree. I work in IT and on computers all the time. Right now, my work PC and all 3 of my monitors are using a total of 50w - 60w of power. They’re running on a UPS so I can check the wattage really easily. I was leaning towards this mostly because of the consistency of the cycles, but it’s not being so consistent anymore.

There’s also the distinct possibility it’s just a phantom “device”. Do you see the corresponding 180+W pattern in the mains Power Meter? Often it’s difficult to tell but that cycle looks identifiable. Post some mains PM zoom-ins for the same period.

Most of them are hard to see because there is usually other stuff going on at the same time. Here are 3 that I was able to isolate. I could probably find more.

This one was during the time period 2 days ago that first made me question whether it was really the air handler. Like I said, the fan is set to turn on only when the AC turns on, and at this point the AC had been off for about an hour. My whole house was sitting under 500w when it turned on. This would have been from my TV/receiver/Shield, 2 air purifiers, and my always on devices.

Here is it turning on just about an hour ago. Very similar pattern, but you can see there is more power being used. It’s likely the AC running since it rarely turns off during the day, it just varies the speed.

Here is another one though from last night though, which is interesting. It doesn’t have the little spike at the end just a few seconds before turning off.

Pure conjecture here but it wouldn’t surprise me if that spike is actually a defrost cycle on a fridge/freezer (which invariably happens once every 12/24 hours) whereas the nice Device waveform that Sense presented you with was a phantom triggering of an actual load. Meaning: some other device signature or power pattern looks like the defrost cycle to Sense.

That said, an actual defrost cycle (if not malfunctioning or triggered repeatedly by a wonky thermostat) usually runs for 10+ minutes to defrost so these short actual spikes (in the mains PM) are not looking like that.

My suggestion would be to ignore things for a week or three and see what is happening then. Feels like Sense is getting familiar to things and in the “confused” stage.

So I may have figured out something in regards to this mystery device. If I’m correct, then I’ve also learned that flipping breakers is not necessarily a good way to figure out what device Sense thinks it’s seeing.

So Sense detected another device. It would run periodically for about 5 seconds and consume about 30 watts. Here’s the graph.

At first I thought I would never figure out what this could possibly be. Sense said it was likely a light, but only 30%. I knew it wasn’t a light because of how it would turn on and off on it’s own even in the middle of the night. But then, I started disabling devices from showing on my timeline and noticed something interesting. This device was turning on about 2 minutes after what I suspected was the air handler (the original subject of this post).

But… I was still not really sure what this device using 30W was, or what the “air handler” really was. At first the “air handler” was running very very consistently. But then it stopped running altogether, for at least a day. So I thought Sense must not be detecting it. But then it started showing Sense again… very shortly after I turned the ice maker in the freezer on. It continued to show in Sense up until the ice box was full and I turned the ice maker back off. It’s now been off for 1d 13h. So, I’m pretty sure both of these devices are part of my fridge. I’m going to wait until the next time I turn the ice maker back on to see if it starts showing in Sense before I call this 100% solved though.

So I’m curious what y’all would do about this? Should I just name both of these devices “ice maker” and merge them? Should I merge both of them with the fridge? How do merged devices show up? Will it just show as one “fridge” device or will it have subdevices showing me the breakdown? If that’s the case, should I merge these two devices into “ice maker” and then merge the ice maker with fridge?

Oh, and I think I found a bug in the Sense app. Notice in my power meter screenshot above it says 0W despite the fact that the vertical line was on a part of the graph that is higher than 0W? Well, this number only goes above 0W when you move the graph. As soon as you stop moving the graph it goes back to 0. This makes it impossible to get a screenshot showing the wattage at a certain point in the graph.