Mitsubishi Ductless mini split heat pump issue

I have a multi unit system and Sense detected (most parts) of it months ago. I got a fair idea of its usage during the summer months. Now that winter is here Sense does not see it in heat pump mode.
From a layman’s point of view it is basically the same just running backwards from the cooling mode.
So… why is it no longer detected? All the usage now shows as “other”
FYI No outdoor drip pan heater installed

@ron111157 , I don’t know enough about heat pump behaviors, but I’m betting the heating “energy signature” is different from the “cooling signature”. It would be fun to see a screenshot of each fro the Power Meter when there is very little else going on. Screenshot would need to include the On transition and Off transition for the heat pump, in each mode. That might tell us a little more.

I’ll try to do that once it warms up a bit and I can isolate a cycle. Too much running now.
Example: For months I’ve been wondering when Sense would detect my coffee maker. It found the Keurig but never saw the normal coffee pot. I started using a space heater in the evening only and Sense found that. But every morning I’d see it was on for a bit at the same time. That can’t be its unplugged. Then I realized its my coffee maker and thinks it is the space heater! Now Sense thinks everything with a heat element is the space heater and I can’t isolate them. What a cluster…
I do know this much. My mini split has three indoor units on one outside unit. The indoor unit has very little effect (minimal) on the Sense signal. One, two or three inside units on looks basically the same. What Sense sees is mostly outside.

Two thoughts:

  • Yup, the outdoor unit of heat pump is the big power user, with compressor, etc. The inside units basically have a fan blowing through a heat exchanger, plus perhaps the controller board. That’s not Sense, that’s the nature of these devices.
  • A lot of us see device conflation where Sense sees multiple devices as the something, especially for things with heating elements. Given the nature of resistive heating, us folks who know the physics aren’t surprised by the confusion - there’s not much to differentiate between heating elements that run roughly at the same power level. You can try deleting the Space Heater and let Sense try to sort out the difference between the two given a little more time and data.

Good luck and hope to see those screenshots when you usage calms down. Hint-you can go back in time to find a place in the history where the cooling On and Off transitions were clearly visible.

Agreed. and the inside units get their power from the outside unit too. Leaving one or more of a multi unit system off does not save you much. In fact that is the one area they may inefficient if you don’t use them to its full potential.

I understand resistive heating. What I don’t get is that space heater took about five minutes and bang! Sense detected it. The coffee maker ran every day for months and nada until now and it thinks it is the heater. The dryer took maybe 10-12 times, oven…not yet. dishwasher…nope. The Keurig…maybe a month. Now even that thinks it the heater until it starts its unique cycling to keep ready for the next cup. Kinda odd!

I haven’t used history other than a day or two back. I’ll look into that

I was reading thru another post and saw the one about a heater and you mentioned something about a new Progressive Detection. Maybe related? It reminded me of a similar odd bubble reaction I had for a short time.

Ok here are a few screenshots. I had to take on the phone and Xfer them to computer. They don’t show on the web app.

First is a several day look. both cool (11th) and heat (12th)

10-11 cool mode

12-13 heat mode

11th zoomed (cool)

12th zoomed (heat)

Not sure why the heat has odd signals. After the 13th the heat was still on but the signals disappeared.

@ron111157 , thanks for posting. Sorry I wasn’t clear with my terminology. What you have posted (and are not available in the Sense Web App) are screenshots from the Device Power Meter, not the main Power Meter. The Device Power Meter shows a sort of reconstruction of what Sense thinks the power waveform looks like from that device based on Sense’s model for that device. It’s not directly based on Sense measurements at that moment in time (unless you are using smart plugs or DCM).

What I was hoping for, was screenshots of the same time periods showing the raw measurements from the Sense Main Power Meter, plus similar screenshots from the cooling transitions. That would allow us to assess similarities and differences between the On and Off transitions for heating and cooling, assuming noise from other devices in the house were relatively quiet at the time.

ok, these are from the main power meter.

cool mode. I think it was turned off on the 10th or 11th in the evening.

Heat mode. turned on the 12th in the afternoon.

Heat mode. On the 14th the mini split timeline showed the unit off at 0715, on at 1427 and then off at 1509. after that it disappeared from the time line and started showing in the other bubble.

There was a space heater running same time the heat was. It is about 1000W cycling around 2-3 off, 5-8 on.

Hope this helps.

1 Like

@ron111157, very helpful. It’s a little tricky because the space heater adds a lot of regular noise to the mix for heating, and shows why Sensing is a challenge. The top/cool shows about 24 hours. The middle/heat shows about 17 hours. Both top and middle have the same vertical scale. Two things apparent in my mind:

  1. Your cooling cycle is variable speed. That’s more challenging for Sense because there is no one uniform on of off transition.

  2. To me, it looks like the heating cycles are indeed different but hard to see under the space heater noise. That would mean that Sense needs to eventually detect heating separately from cooling.

It did take quite awhile for Sense to find the mini splits when cooling but has been pretty consistent until now. I am pretty sure the heat mode is variable too just not as pronounced. I think the system has a delay circuit that keeps the inside fans off until a certain temp is reached. That prevents it from blowing cold air into a cold room. I do know the outside fan varies just like it does when cooling.

We are having a unusual cold spell and temps are running about 25+ below normal. It typically may last a day or maybe two but this has lasted a week so far. Hopefully in a few days I can turn off the space heater and set the mini splits for cool nights. I’ll screenshoot again for new heat reading.
It’s just odd that for the first 2 and half days it showed the usage correctly under mini split and then poof it was gone and jumped to other/always on.

I sure hope it finds it again before we have really cold nights! The defrost cycles when in heat mode will really confuse it. 45-50 minutes heat mode, then 10 in cool mode to melt any ice off the outside fins and repeat!

1 Like

Two bits of experience from a longtime Sense user and someone who tries to understand Sense behaviors.

  1. Don’t be surprised if Sense recognizes your mini-split on a piecemeal basis. Things like the defrost heater and individual head-end fans look like separate devices though Sense is trying to get smarter about meriting them. But if they come on at different times, they might be seen as different devices and you’ll need to merge if you want to see combined.

  2. There are situations where Sense recognizes something then seems to forget. Lots of reasons. Heating and cooling often drift in power usage behavior through a season and between seasons. And as more data comes in one more devices, Sense can sometimes become confused as well. Don’t feel bad about deleting a device that once was recognized but hasn’t shown up for a few months. If and when Sense recognizes it again, Sense will do some level of backfill of detections.

I have found that to be exactly how Sense behaves. I have had all those situations and more. If you are a layman user its counterintuitive to your expectations. If you have some electronic and electrical experience it is downright frustrating. Overall I still find it useful and informative but does require some patience! Here are a couple of examples of the things you talk about for any eager layman that’s interested. Just be patient!!

  1. Sense “found” my fridge after a month or so BUT only the water dispenser, a few weeks later the ice maker motor, couple more weeks the 2nd ice maker. The remaining parts… not yet. Sometimes Sense has an idea what it found, other times it just says something way off base or motor, device#, etc.

  2. Sense “found” my Kuerig coffee maker But only sees the big spike when its turned on and heating water. It does not the see the dispense mode or the small spikes every few minutes where the unit is keeping the water hot for the next cup. Well let my clarify that. It does see the spikes on the power meter but the Keurig bubble goes away after the initial warm up.

  3. Sense found my Phillips LED bulbs instantly. It sees them cycle on an off with the dusk to dawn timer, go from dim to bright everday. All this happens below 5w usage. 5 Watts! Sense does that consistently and flawlessly!

Last, since this post is about my mini split heat mode. Ironically Sense saw it yesterday for all of 30 seconds, LOL

1 Like

Thanks @ron111157,
I’m a former electrical engineer, who eventually ended up in software, so I really love this gadget, because it brings back memories of my junior year labs on power engineering (dubbed SuperLab, the power lab sessions took place in a room that looked a bit like Dr. Frankenstein’s lab, with huge exposed copper power busses everywhere, carrying 3-phase and split phase electricity to motors and transformers).

After poking a little more into how Sense does its current identification, a couple of the things you are seeing aren’t quite so counterintuitive.

  • Each component of complex devices has it own On and Of transition which each have their own physics characteristics, hence discovery of the fridge water dispenser separate from the compressor, separate from the defroster. And the clues that Sense currently uses to differentiate can’t completely discern. As you have seen, resistive (heating) devices don’t give much to go on except the house phase they are connected to, plus their resistance value. Motors (essentially coils of wire) can look similar to transformers, and older microwaves use big transformers, so they can sometimes get mixed up.

  • Your Philips bulbs are probably being detected via the Hue Integration, which uses a different mechanism for detection, than Sense “native detection”. With Hue bulbs, Sense gets the on/of and power information from the Hue Hub, not by looking for the 5W transitions on your house mains.

I would agree however the key word here is “layman”. The average person that is looking to get the latest gadget or app is expecting it to do exactly as advertised. Most people have no idea how electricity works and frankly don’t care other than don’t touch that or how much it costs.

For those of us with “some” knowledge know the days of a fridge is a fridge is a fridge are over. Everything has a circuit board inside. Everything is “smart”

My background started with tactical communication and the days of tubes, 400 cycle 3 phase and RF in the 10s of thousands of watts. Software was that thing that took a big room to house, lol. Fortunately those days quickly were giving way to digital

Yes the Philips bulbs have a Hue Hub and it works wonderfully. Wished we had more integration items like it. Actually I got to complement my Apple software. The Sense integration was a bonus.

I am sure the base of customers is quite varied. They want a plug and play solution. I mean come on Sense is its name! get to Sensing dammit, lol. To those like us its a tool, a toy, a challenge.

So remember to us it may not be counterintuitive but to the don’t stick a fork in the outlet crowd is it really?

1 Like


These snapshots are of the defrost cycles when in the Heat mode. They are pretty typical of a defrost cycle, every 50 or so minutes and last 8-10 minutes.

I have yet to find the on and off cycle of heat mode. It can be subtle to detect in the warmer weather running very quiet and when colder it runs almost constantly. The popup bubble (heat pump) varies between around 350-1100 watts which is obviously still missing some of the actual usage. Why? Because the other and always on bubbles are still my biggest users. There are times when I’m puling 6K watts and the only two things that could use big power are the Mini-splits and a space heater (1100w). The space heater has a bubble. I know my average house usage when those two are NOT ON I see a typical average under 1000watts.
A good portion of the mini-splits still show in the other and always on bubbles.

Three typical cycles of a defrost mode.

One cycle expanded

Typical bubbles

Hope this helps!

1 Like

Mini split related??? I got a new “found device” named heat 4 about 10 days ago. Sense thinks it is a dishwasher 69%, next best guess is Toaster 4%. Neither is correct because they haven’t been used for weeks now. HVAC is a 2% guess and I think it is that. I have not merged it so I can monitor it for awhile.

Odd thing is it only comes on once (sometimes twice) a day. It averages about 680-690W and runs about 20 minutes. It “detected” it about 10 days back BUT looking at the history the daily spikes go way back to mid Oct. This happened during both the cooling and heat modes of the mini split. I am reasonably sure its the mini splits because on the rare days is was OFF, no spikes.

Any ideas of what function/cycle of a typical mini split this could be??

I have included a snapshot of the latest peak. Unfortunately the consistent spikes you see on top of it are the Keurig coffee maker maintaining heat between cups.

Do you know if this is a inverter model ? Or a model number ?

It is.
Outside unit, 1 Ea. Model # MXZ-4C36NA2-U1
Inside units, 3 Ea. Model # MSZ-GL12NA-U1

The outdoor unit is an inverter driven variable speed compressor pump unit with an electronic linear expansion valve.
The indoor units have multiple fan speeds and multiple airflow directions. Your system also has a branch box. and doing multi-zones. I am not sure that sense can detect all this. Once the power gets to the inverter… the inverter to the compressor generates its own sine wave at a different frequency than the input. It literally has a micro-processor in your outdoor unit that controls the inverter. I am surprised that it has found maybe the signature feed to the inverter in cooling mode. The compressor doesn’t run backward, it changes the direction the freon flows… still goes thru the compressor the same direction the changes the direction at the reversing valve. Let say the Freon is always hot coming out of the compressor, like boiling hot and become gas.

In AC mode, the hot gas runs thru the outdoor unit first which helps it cool down as it cools down, it becomes liquid again … then it hits an expansion valve on the other side of the expansion part (orifice or TXV) the expansion valve will also have a high pressure on it because it all has to all go thru a small orifice as liquid. When it makes it thru the that there is a lot lower pressure on the other side because its not back up. The result here is just like emptying a CO2 cartage where the outside of the cartage get really cold other than instead of it going out in to the air… its still inside a pipe. It actually warms up while in the inside coil from the return air blowing accrossed it… The freon returns back to the compressor to do it again.

In the heat mode… the hot liquid from the compressor is pumped into your house coil first… everything is the same and your outside unit blows the outside air accrossed it to warm the freon up.

The defrost cycle on yours will actually run the AC cycle (hot freon in the outdoor unit for a few to melt any ice) without running the indoor fan.

Also keep in mind off your outdoor unit, you have a big line and a little line (maybe 3/8’ and 5/8") so when the same volume is trying to go thru the 3/8 vs the 5/8 the pressure is different and the engineers at Mitsubishi probably has a different starting frequency in heat mode vs cool mode as well as the timing of kicking on the indoor fans.

You having an inverter driven variable speed compressor with multi- zone and each multi- speed/ direction indoor units… I would get the flex sensors try to get all the L1 wires associated with the HVAC system in the one clamp and L2 associated with it the other. I think you’ll drive your self crazy trying to each part of your mini splits into one bubble especially since there are now multiple ways that sense will detect a device or signature and you arnt going to know which type of detection your looking at and you have 3 of the same indoor units. Even if they were just 2 speeds each… what happens with 2 are on high at the same time. Maybe you would have 1 in the “Parts of the mini split” the 2nd one going to the “other bubbled”… maybe both in “other bubble”. If its found the signature of an indoor unit and a 2nd one kicks that got the identical signature… I assume the same thing.

1 Like