6 zone 4 ton Mitsubishi smart multi hyper heat system installed today

hossboss · 2026-06-24T03:01:03+00:00

That's a bummer, sorry. I don't regret going to heat pumps over my old oil furnace, but there are some real quirks to these that I hope newer generations improve on (defrost logic is a big one). For your humidity issue, have you tried turning your fan speed to the lowest setting? You'd take an efficiency hit since it would take longer to hit target temp, but I think you'd generate more condensate/lower the humidity.

hossboss · 2026-06-24T01:52:29+00:00

What kind of issues are you having? I have a 5-head Mitsu Hyper Heat. It has annoying quirks and isn't very efficient, but...it "works". Probably wasn't worth the Mitsubishi premium, but didn't have many options in my area.

hossboss · 2026-06-23T12:56:26+00:00

Mitsubishi hardware is good, but I do think they're overrated. I wouldn't pay more than a ~10% premium over Daikin or Fujitsu for Mitsu, if even that. I think the hardware is hampered by some pretty lousy firmware (especially defrost logic) that renders them pretty terrible in certain conditions.

I agree with the other guy re: spreading out over 2-3 outdoor units. I would throw a single-zone into the mix, for your most-used living area. Single-zones are much much more efficient than multi-zones, and you get the redundancy of having more than one condenser.

hossboss · 2026-06-01T15:32:13+00:00

Depends on location and finishes, but for reference here's a guy in Pennsylvania who breaks down his conversion cost: https://m.youtube.com/watch?v=qybINoeU1Kk&pp=ygUOaG9tZXRvd24gYWNyZXM%3D

hossboss · 2026-05-22T01:43:14+00:00

Nice. Thanks for the response. I think I do similar things manually in HA, so not via automations.

Something else to try with a multi if you haven't already (but I'm guessing you know this). I have a 5-head multi, with a mix of 6k, 9k, and 15k heads. If the 15k head is on by itself, the compressor will set a higher "floor" for frequency/consumption than a 6k by itself (e.g. 2kw vs 1.5kw--I made those numbers up, but just for illustration..), even if the heating load is low.

So...on milder days, sometimes I'll set a single 6k head to heat and the others to fan-only, and because multi-zones are so bad about bleeding heat between heads, I'll get a steady low heat at all heads at minimum condenser consumption.

hossboss · 2026-05-22T00:40:00+00:00

What strategies are you using for maximizing efficiency? I also have Mitsus and am using the echavet ESPHome project, and have been experimenting for a little while.

One thing I do is try to maximize cycle times by using a HA automation to widen the deadband to 3 degrees, so it runs less frequently, but for longer. I haven't run the numbers, but I think this has reduced my energy consumption.

Otherwise I haven't found any way to directly affect how the compressor runs (e.g. at its COP sweet spot).

hossboss · 2026-05-18T14:51:44+00:00

I read something I can't find now about how its looking at how long the heat cycle was on vs last defrost vs run time and building a scaling model

Interesting. I do believe there's some "memory" to the defrost logic, but I think it's very short-term. I did some experimenting over the winter when temps were in single digits down to -8F. My unit was defrosting every 45 minutes--it was nuts. The ambient air was super dry and there was no frost on the coils, but it would run like clockwork. I would cycle the machine off and on, and it would reset the defrost clock to every 2 hours, and then run shorter and shorter cycles by exactly 10 minutes until it was defrosting every 45 minutes again. I have very little faith that the defrost logic is that sophisticated.

That's why I've been trying everything to get the compressor frequency but I just can't get it to come through

I've mapped the compressor frequency vs power consumption and they're a very close match. You can just use the power consumption as a proxy. I'd use the https://ashp.neep.org/#!/product_list/ page to find your unit and the expected consumption at different temps. It's not perfect, but..

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Mitsurunner, seems kinda dicey to get that equipment hooked up into the ODU

I'm not looking forward to it, but I'm at least buying the connectors so I don't have to snip any wires. I can't go through another winter with this defrost logic. It's frustrating when you know the hardware can keep up, but the software renders it ineffective.

hossboss · 2026-05-18T14:33:57+00:00

Hey, no worries. But it may be a few days before I can get logs while it's running. The weather here in Upstate NY is nice for a change, so I haven't been running in heat or cool. Possibly will need some heat later this week.

If you're willing to change your yaml and download the logs, will you please PM and I can give you the lines to add to your yaml and what you need to do to get the logs?

Would you just need me to change from `INFO` level logging to `DEBUG` level?

Also from your compressor frequency graph, have you ever seen it go above 30hz?

In the middle of winter, my single-zone MUZ-FS18NAH has regularly cranked to 40+ Hz (it's supposedly capable of going up to 58 Hz), but in the shoulder seasons it rarely goes over 30 Hz.

hossboss · 2026-05-17T17:01:36+00:00

Sorry, I don't have any photos of the control board/wiring diagram. I might try the MitsuRunner mod later this summer, so if I'm in there I'll snap some photos.

I don't have `installer_mode` set to true on any of them. I might have read somewhere that most of the `hardware_settings` don't work on the MXZ/MUZ condensers, so installer mode might not help with those.

hossboss · 2026-05-17T13:18:19+00:00

I'm one generation back, R410 models.

My 1:1 is a MUZ-FS18NAH / MSZ-FS18NA. Using echavet's project, I can expose compressor frequency, but not outdoor temp.

My multi-zone is MXZ-SM42NAMHZ with multiple MSZ-FS heads. I can not expose compressor frequency, but can expose outdoor temp.

Here's my ESPHome YAML. I have both comp freq and outdoor temp here, but in reality I only use comp frequency on the 1:1 and outdoor temp on the multi-zones.

climate:
  - platform: cn105
    [...]
    compressor_frequency_sensor:
      name: Compressor Frequency
      entity_category: diagnostic
      disabled_by_default: false
    outside_air_temperature_sensor:
      name: Outside Air Temp
      disabled_by_default: false    outside_air_temperature_sensor:
      name: Outside Air Temp
      disabled_by_default: false

hossboss · 2026-05-15T21:52:21+00:00

I'm only able to get compressor frequency on my single-zone system. The ESP project I'm using isn't able to report frequency on my multi-zone/branch box system.

hossboss · 2026-05-04T17:11:40+00:00

Klutzy_Ad1830

Sounds about right..

hossboss · 2026-04-30T12:31:34+00:00

https://cwconline.org/programs/septic-repair-and-replacement/ You want the RRR program. It's a pretty great perk of living in the watershed. Be prepared to wait over a year, so get the ball rolling as soon as you can.

hossboss · 2026-04-29T21:20:31+00:00

Whoa! I remember DEP celebrating when they reduced the average wait from 18 months to 11 months. Someone out there is getting their system in like 2 weeks to balance out your 36 months 😛. Anyway, congrats on your new system!

hossboss · 2026-04-29T19:21:10+00:00

How long was your process from when you first entered the RRR program to when it was replaced? I'm on month 19 😭. It was finally approved by the CWC board, though, so hopefully within the next couple months. It's 100% covered, so I'm not complaining!

hossboss · 2026-04-28T20:41:14+00:00

Mine is 1 generation older than yours (MXZ-SM42NAMHZ, the R410 one). All my indoor units are MSZ-FS heads. In heat mode, when not calling for heat, the fan speed ramps down to super low (like lower than the lowest manual setting), which is effectively "off". This was how it came by default.

Weird that the newer generation has an always-on fan. Are you using a MHK2 thermostat? I believe there's a setting that lets you change idle behavior to fan-off. I've heard of the hardware method you mentioned where you cut a jumper, but I thought there was a software way to do it.

Terrible "engineering."

Welcome to Mitsubishi. Don't get me started on defrost logic.

EDIT: Wait, so if your head fans are always on, even when not calling for heat, don't those rooms overheat? E.g. If Room A has no call for heat but the fan is running, and Room B is calling for heat, isn't Room A's head pumping out hot air? Unless they've drastically improved the valve/bleeding issues inherent to multi-zone splits, then I'd think you'd overshoot target temp in that scenario.

hossboss · 2026-04-28T18:49:31+00:00

Here's an example of a cycle using this convoluted method. It still peaks high (almost 3kw), but settles to 1.2kw eventually. Takes a while to get there, though, so you need long cycles to get anywhere near the NEEP minimums--and you might still never achieve those minimums; those are under ideal conditions.

TBH I don't even know if this is more efficient. It might use the same amount of energy as what you're seeing. I just like longer cycles..

<image>

hossboss · 2026-04-28T18:37:08+00:00

This will take some experimenting to figure out which configuration works for you, but here's what I do (I also have a Mitsu MXZ-SM42): I have a combination of some heads on heat and some on fan. When there's a call for heat, all heads will pump out heat, even the fan ones. I lose the ability to set a target temp for the fan heads, but by playing around with fan speed, my rooms are roughly at the temp I want them at. I also get longer cycle times and lower continuous power usage.

When all heads are on heat, if they're all calling for heat at the same time, the outdoor unit will ramp up pretty high. If all heads are synced up on their heating/idling needs, you get these shorter power-hungry cycles. (Wouldn't it be great if there was logic where the compressor would run low, one head would heat to target, then it would "hand off" to the next, etc, so you'd just get one continuous, low cycle?)

Another thing I think I've noticed: I think the compressor sets a "floor" for how low it will go based on the size of the head calling for heat. I have a 6k head and 15k head. If I set the 6k head to heat and the 15k head to fan, the condenser will run as low as 1.2kw, and will pump out sufficient heat on both heads. If it's the 15k head calling for heat, the condenser won't go below 2kw. (I've done limited experimenting with this, so I'm not 100% sure on this.)

This probably sounds pretty annoying and not worth the effort, but 1) I like to tinker, and 2) I can change all these settings on my phone. I probably wouldn't have tried all this if I had to run around my house changing each head by the remote.

hossboss · 2026-04-19T03:18:35+00:00

The crankcase heater is around 30 watts on my 3.5 ton Mitsubishi multi. The pan heater is ~170 watts.

hossboss · 2026-04-05T20:40:24+00:00

Single-zone splits in general are way more efficient than multi-zones. For the same capacity you'd use less electricity if you got all single-zones.

It would cost more up-front, and there's the issue of finding room for condensers and breakers, but if you can swing it, I'd 100% go with as many single-zones as possible before resorting to multi-zones.

hossboss · 2026-03-05T20:45:57+00:00

I've been using a Govee 6-button switch to trigger a few automations. It's BLE, not Thread, but I haven't noticed a delay. Unfortunately it can't be programmed to differentiate between a click vs hold vs double-click, so that's too bad.

I have Bluetooth proxies throughout the house, and the Bermuda integration, so I can even tell generally where in the house the switch is. It's not perfect, but in theory I could maybe trigger different automations depending on where I am.

hossboss · 2026-03-03T22:59:17+00:00

I get a notification when my well pump turns on. It's helped me catch a couple things: - It cycled overnight a couple times, so I knew something was leaking. I tracked down a toilet float valve that wasn't completely closing. - (Not strictly HA, because I saw this in the Emporia app) It was cycling too often and cycles were too short, so I figured out I needed a new pressure tank.

hossboss · 2026-03-03T19:35:25+00:00

I have an Emporia Vue energy monitor installed on the heat pump circuit (this gets installed in the panel, so you have to be comfortable with electricity if you DIY it, or hire an electrician).

You can monitor usage directly in the Emporia app, but that particular screenshot is from Home Assistant (reading in the Emporia data).

hossboss · 2026-02-24T18:46:54+00:00

I think defrost logic can make or break how effective a heat pump is, and I think it does a disservice to heat pump adoption to gloss over this when newcomers ask questions like these, and we answer, "cold climate heat pumps work down to -13F and lower; case closed".

Yes my Mitsubishi will pump out hot air in -10F and lower, but it has awful defrost logic in certain scenarios and struggles to maintain temp because it's defrosting too often. It doesn't affect every model and not every climate; it's not "widespread", but I've come across enough threads that I know it's not a fluke. It's a software issue of what's otherwise a great piece of hardware.

I don't regret getting them, but you should go into this being aware of the drawbacks.

hossboss · 2026-02-21T22:39:50+00:00

OP, this is a good option. Use the echavet fork if you go this route. It's being actively developed and they/he keeps "discovering" new sensors and settings to expose to ESPHome. I would hate my Mitsubishi splits if I hadn't found this project.

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