Mini Split

#1

Recently Device 1 and Device 2 (wife calls them thing 1 and thing 2) showed up at the same time. After several weeks of observation their pattern (almost identical) is a cycle, on every 45 minutes for appx 20 minutes, each with an average usage of 29w.

Fairly certain they are related to our mini split AC/Heat unit as they go away once I turn the circuit breaker off for that unit.

Thing is we have not turned on the mini split system this season as we heat with wood. Perhaps someone can validate my conclusion that this power is just being used by the units standby mode.

Guess my question, in an attempt to contribute to the Sense collective, is why there are two devices (perhaps one for the inside unit and one for the outside unit?) and what would be an appropriate Sense name for them?

#2

I’ve not yet figured out how each and every device is seen by Sense, but a mini-split could be as many as 4 devices and possibly many more…

yes, there is an outdoor device (condenser) and an indoor device (evaporator)… those are the basic pieces, but the energy signature could be much more… the condenser has a fan and a compressor, those could come up as different devices… the indoor unit could be a single head (evaporator) or could be multiple heads (evaporators in more than one room)… each evaporator has controls and fans, those could be separate devices in Sense as well…

some of these mini-split systems have advanced controls… they can be setup to circulate air in the room even when the unit isn’t running… “air mixing” is what I’ve heard it called in certain circles…

29W is not enough for the compressor to be running… such a low wattage could be a fan and related controls… supports more of “air mixing” rather than running… without specifics of make/model, its the best advise I could give… running every 45min for 20min cycle, could be just mixing the air in the home or room…

hope this helps…

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#3

I found that my 1800 btu Gree minisplit draws a constant 75 watts in use or not. Since I only use this unit for air conditioning I flipped off the breaker until next cooling season. Sense has not detected the mini split but it’s current is monitored by an independent c/t (part of my demand load controller).

#4

Sense has likely found the compressor sump heater for your mini splits. This heater keeps liquid refrigerant from pooling in the compressor sump. It turns on when the compressor cools to below 80F or so. This is common in heat pump units that operate during the wintertime.

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#5

Exactly what I was going to say. It’s another phantom load most people don’t know about or understand until a device like Sense brings it to their attention.

Turning off the breakers to any outdoor condenser units during the months they are not used will remove this load. Just be sure to turn the breaker back on 12 or 24 hours before you plan to need them again in order to let the heating element do it’s thing and bring them back up to operating temperature beforehand.

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#6

@oshawapilot @pswired
Thanks for the feedback, I wish Sense was the device that detected that load. I actually found it during a data audit of my demand load controller. It has dedicated c/t sensors for my 4 major loads in my panel. Hopefully someday Sense will detect these mini split units.

#7

So after 2 days my first device was detected and labeled “heat pump”. Hoping this was my living room Mitsubishi mini split I turned it off remotely since I was at work. The sense app showed it turning off so I figured great my first device. The problem is it only showed 96W consumption and it never varied. I have the fan set on auto so I know the speed changes and even though it’s a very efficient Mitsubishi hyper heat unit that seems like awful low consumption. So when I stopped home I turn the fan from Auto all the way up to 4 and it stayed at 96W. Furthermore when I was away from home it would cycle on and off even though I knew the unit was on. So when home I turned the temp down from 69 to 61 and the fan on the outside compressor shutoff at the same time the Sense app showed the mini split shutting off so I assume it only picked up the usage of the compressor fan? Maybe it’ll pick up other parts of the unit and label them as separate devices? When I turn the temperature setting back up to 70 the compressor kicked, the app showed the unit on and using 96W AND my other consumption shot way up.

#8

A mini-split like most compressor-based devices, is an aggregation of many electrical components.

Sense is a disaggreagtor of device electrical signals … and devices often present multiple component electrical signals … so what Sense does is effectively dissagregate and then re-aggregate (combine)! Difficult task!

The “96W” Sense is identifying may well be one or several components in the mini-split. e.g.

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#9

Thanks. I figured it was only one part. My assumption that it’s the outside fan is the fact that it, unlike the inside fan, cycles on and off when the unit is on. Hence Sense showing the unit turning on and off when it’s on. I get that it’s a complex task with a device like that and hopefully it can find the other consuming parts of the unit AND combine them. Even if it does find more how will I know if it is showing all of the consumption of the unit?

#10

For now I think we’re more in the 5% confidence realm (or less) for mini-split tracking vs. the 95% confidence where it seems “reliable”.

The temptation to draw a parallel to weather forecasting is too great (air conditioner!): Even with supercomputers and satellites, “100% chance of rain” is still only telling you that, say, “in the next 24hours it will rain”. That precision has improved perhaps to “in the next hour” … but we’re still a long way from making weather prediction seem like astronomical prestidigitation.

#11

That’s why I was tempted to buy a different monitoring system that had CT clamps for the mains and smaller ones for each circuit you want to monitor. I chose Sense because of the cleaner installation and the hope of monitoring a lot of circuits without clogging my breaker box.

#12

Sense does have the advantage of measuring a million times a second so it can provide finer details than other systems (which I think read a few 10s or 100s per second) although the real time monitor only shows to 0.5s resolution.

#13

Ya I bought it because of that and the cleaner installation. Also the hope of improvement over time. Like most things there are advantages and disadvantages. I figure for something like my mini split I’ll get a clamp meter , turn the heat way up and compare the app reading to the clamp meter on the outside whip.

#14

As an update my mini split is now showing variable usage all the way up to over 800 watts so maybe it’s figuring it out. On a side note it says it found my fridge and when I heard the compressor kick on the fridge bubble popped up in order to confirm I killed the breaker to my refrigerator yet the bubble stayed there. I was wondering if there is a latency to when it would disappear in the app. Also with the fridge set to its coldest setting I turned the breaker back on and the other bubble expanded a lot?

#15

Switching off a breaker is not a reliable method to “trigger” Sense … when Sense is looking for patterns they are at a much higher sample rate than what we imagine as “on/off” … in those (normally) device triggered on/off cycles (vs a breaker switch) there’s a lot going on. Sense is likely to misinterpret breaker switching.

It seems like you are seeing evidence of the Sense brain getting smarter (in regard to your house) so I would try and keep things as “normal” as possible and let it do its thing!

Lazy wins!

#16

I can handle lazy in this regard, I have plenty to keep me busy. I was just wondering how to decide whether to agree in the app that what was found was my refrigerator.

#17

Turning off the breaker is undoubtedly a different signature than the refridge shutting down after a cooling cycle.

Some modern refridges work only as hard as they need to (a bunch of modern heat pumps do likewise), and it sounds like yours may operate that way. When you think of it, proportional use of power is far better and much more efficient than the bang/bang switching of old units.

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#18

Oh I know, on and off is also harder on the motor. I just figured if I killed the breaker the bubble would go away and confirm its the fridge.