Adding a Programmable Thermostat to Mitsubishi Mr. Slim Heat Pumps

As part of an ongoing energy upgrade of my 1930 home, I had four Mitsubishi Mr. Slim mini-split heat pumps installed (three MUZ/MSZFE09NA 9000 BTU units, and one MUZ/MSZ12NA 12,000 BTU unit.)

If price had been no object, I probably would have gone for Waterfurnace’s (TSX:WFI/OTC:WFIFF) Series 7 or Climatemaster’s Trilogy ground source heat pumps,  but my home’s existing heating is an oil boiler and radiators, and the Series 7 would require installing air ducts throughout the house.  The mini splits have the advantage that the refrigerant lines can run up the outside of the house, making them much easier to retrofit.

The geothermal systems I was quoted would have cost $50,000 to $60,000 (minus a $500 rebate from my utility), while the mini-splits cost $15,500 (minus a $2000 rebate.)

Because I’m also doing extensive insulation and air sealing, my heating bill is only about $2000 a year, even using oil at over $4 a gallon.  After using the air source heat pumps for two months, I expect these mini splits will approximately halve that.  The geothermal system would have done better, but even if it cut my heating bill by an impossible 100%, it would have taken 25 years to pay back my investment.  The mini-splits will have an estimated payback of about 13 years, which is not great, but both they and the geothermal system have the added advantage of giving me efficient air conditioning in a home that did not previously have it.  In New York’s Hudson Valley where I live, A/C is only useful for about 1 month a year, but it’s sure nice to have during that hot and sticky month!

In any case, I’m happy with the mini splits except for one thing: they have very limited programability, something I did not realize before I had them installed.  The best you can do with the included remote controller is set them to turn on and off once each during a given 24 hour period, and you have to manually set this up every day to use them that way.

There is an available programmable thermostat (Mitsubishi kit MHK1), but it is intended to be installed with the heat pumps, not after the fact.  My HVAC contractor offered to install them anyway, but he wanted $350 each, or a total of $1,400 for all four.  That’s not unreasonable, since the MHK1 retails for  $243, but it was more than I was ready to pay.

Since he told me he would have to figure out how to do the install from the documentation, and I had seen him struggling with the translated-from-Japanese when he was trying to figure out what was wrong with one of the units when it was first installed.  (It turns out two of the wires were reversed.)   I’m decent at that sort of thing, so I decided to give it a go myself.

There was one point where the documentation was completely unhelpful.  I figured it out eventually, but the rest of this post should save you a lot of trouble if you’re trying to do the same thing.

Installing Mitsubishi Programmable Thermostat Kit MHK1 on Mr. Slim Heat Pumps

  • Tools needed: Phillips screwdriver
  • Time required: 15 min (experienced) to 1 hour (first time).


Not only does the manual say to install the data cable before the heat pump is installed, there is no information about where the “CN105” connector on the control board is to be found, or even where the control board is.  None of the documentation I found online was any more helpful.  Eventually, I figured out where the control board and CN105 connector were, and how to get to them.  Here’s how:

Turn off the power to your heat pump at the circuit breaker.

Remove the horizontal vanes

Remove the horizontal vanes

remove screw covers

remove screw covers

Covers removed... screw locations circled

Covers removed… screw locations circled

After 2 screws holding the unit cover are in place, the cover can be removed by pressing in around the edges, and popping it off.

When the cover is removed, the bar containing the i-see and indicator lights may swing down.

When the cover is removed, the bar containing the i-See and indicator lights may swing down.

Don't panic, just hang it back on the two plastic hooks like the one shown here

Don’t panic, just hang it back on the two plastic hooks like the one shown here

Now remove the Emergency operation switch by pressing on the tab shown here

Now remove the Emergency Operation switch by pressing on the tab shown here

You can now remove the screw that holds the control board cover

You can now remove the screw that holds the control board cover and remove the cover to access the board.

These wires, too.

You’ll need to disconnect this wire to slide out the control board.


This wire, too.

Now you can gently slide out the control board and connect to the CN105 port, shown here.

Now you can gently slide out the control board and connect the control wire to the CN105 port, shown here, circled.  It’s located in the bottom back corner of the control board.

You’ll want to snake the control wire through the unit so that it’s hidden when everything is installed.   Make sure you’ve left plenty of slack on the control wire, so it does not pull off when you put the control board back.

Now you can reverse the above process to put everything back where you found it.

You can now connect the wireless receiver, and proceed as described in the installation guide.

You can now connect the wireless receiver, and proceed as described in the installation guide.

The rest of the manual was no harder to follow than these things usually are.

It took me a few hours to figure this out… hope I can save a few readers the aggravation.


  1. Frank Touper said

    I’ve looked into the wired option for my MXZ/MSZ setup. Thanks for the detailed write up. I agree with you on the limited programmability of these units. Why can’t someone make a centralized universal/learner remote control that is programmable with multi-room addressable wireless IR blasters. Problem solved! Heck even connect it to the internet for smartphone control. With the growing popularity of these high efficiency systems you would think someone would make these…. hello Logitech/Harmony, wink$wink$.

    • mjw said

      IR blaster solutions are uni-directional. You could perhaps turn the air conditioner on and off, but you wouldn’t be able to get info back from the air conditioner such as
      – current temperature
      – target temperature
      – current mode (hearing, cooling, etc)

    • AbsoluteJoe said

      ATTENTION “Forward Thinkers” at Honeywell and Mitsubishi !

      I join the frustrated in trying to design a HVAC system without complete specs.

      Does anyone know what wall unit functions are supported by the MIFH1 Honeywell RedLINK interface ?

      Even though the RedLINK interface is licensed by Honeywell to Mitsubishi, and others, there has to be documentation somewhere listing the functions that the protocol supports.

      Is there a tabulated list of the Honeywell RedLINK functions Mitsubishi supports ?

      Are there any Honeywell RedLINK enabled thermostats that can control all, or most, of the Mitsubishi wall units functions ?

      • Tom said

        Redlink (according to Honeywell customer care, supports all the important functions but not if you are using the MHK1 thermostat. Honeywell support says you need a Prestige or Prestige IAQ thermostat to support dehumidify.

        Using the MHK1 thermostat, I can change the mode between heat/cool/auto/dehumidify (dehumidify requires changing an installer preset), as well as vertical vane angle and fan speed. I cannot control the horizontal vane angle or set auto off/ auto on from the thermostat, although programability mostly takes care of this.

        The web/smart phone interface is worse. It can only change the temperature and the mode to heating, cooling, or off. Dehumidify and “auto” modes are unavailable, as is any control of the fan speed and vane angles. When the unit is in dehumidify mode, the iPhone app says mode is “unknown” and the web app does not say anything.

        As far as I know, there is no option to buy the MIFH1 with any other RedLink Thermostat, so if you were to buy one of the Prestige thermostats, you’d have an extra one.

      • AbsoluteJoe said

        Thanks for the quick reply Tom…

        I found at least one online vendor that sells just the MIFH1 (175USD) and CN105 cable seperately.

        I was planning to use it with a Prestige 2.0 or IAQ with EIM in order to control both the MXZ/MSZ and the existing hydronic baseboard for aux or backup heat from a single smart wall thermostat – the Prestige. That way I can tune the system to choose the most economical heating, hydronic natural gas or electric heat pump – and hide the MXZ/MSZ remote control in safe place.

        OK, so “Redlink (according to Honeywell customer care supports all the important functions” but I’d like more details about the “important functions”
        the Prestige IAQ will be able to control – does it at least control every function that the Mitsubshi MHK1 thermostat supports (like fan speeds) ? For example,I don’t see anything about selecting fan speeds in the Prestige IAQ install or user manuals.

      • Tom said

        I don’t know any more details regarding the Prestige thermostats. I suggest emailing customer care. I’d appreciate it if you let us know what you find with a follow-up comment.

        Considering I was able to buy all my mhk1 kits for less than $150 each including shipping on eBay, I don’t see a lot of advantage to paying $175 for the MIFH1 separately, although it’s nice to know it’s there.

      • AbsoluteJoe said

        The Mitsubshi thermostat that comes with the MHK1 looks like a custom branded version of the Honeywell wireless FocusPRO w/RedLINK. But I’m not sure if it can support the FocusPro EIM and the MIFH1 at the same time. One of the Prestige IAQ install examples does show support for more than one EIM. And I’m gessing that the MIFH1 may look like an EIM to the Prestige,

        I guess that I need to send an email to
        I will reply with a followup if they are able to give me a more complete answer.

      • Tom said

        I look forward to reading what you find out.

      • AbsoluteJoe said

        Given all the “Forward Thinking” fanfare and hype about Mitsubshi’s adoption of Honeywell’s RedLINK standard, I got a disappointing reply from Honeywell ECC. Even though the Mitsubshi branded RedLINK-enabled devices are licensed and manufactured by Honeywell, they are not necessarily able to connect, communicate, and/or interoperate with their “vanilla” Honeywell RedLINK peers or equivalents. I’d like to know if anyone has been successful in getting a Mitsubshi RedLINK-enabled unit to work with any Honeywell RedLINK devices, including the RedLINK gateway.

        Here is the Honeywell ECC Customer Care Response:



        Thank you for contacting Honeywell.

        The MIFH1, although built by Honeywell, uses a proprietary Mitsubishi communication protocol to translate and transfer commands between the Mitsubishi equipment and the RedLink enabled products that can also be used with it.

        We would recommend contacting Mitsubishi for further, and any more specific, information that may be available.


        Honeywell ECC Customer Care

        Suggestions and recommendations made by the Honeywell Customer Care are provided, without charge, as a complimentary service and are therefore given on the express understanding and agreement of the recipient that they are given without warranty (express or implied) or liability of any kind. It is the responsibility of the recipient of this message to verify that a Honeywell Customer Care Center recommendation or replacement suggestion is suitable for installation or implementation. This may require referring to product installation instructions, contacting the original equipment manufacturer (OEM), or contacting a qualified service person or taking other appropriate steps. Final responsibility for the selection and application of a control or procedure rests solely with the installer.


        Case Number:********


      • Tom said

        Yeah, that was not very helpful. Maybe we’ll get something from Mitsubishi.

  2. Tom said

    There actually is a central thermostat for these, but it requires that you install individual thermostats first…. The central controller is MCCH1. There are apparently a number of devices which work with Honeywell’s “RedLINK” network… but all of these require the installation of the wireless receiver and cable (MIFH1 – part of the MHK1 kit) which I describe how to connect above.

    There is a redLINK internet gateway available.

    My complaint is that the mrk1 should be included with the units, rather than the remote control.

    I’m personally planning on installing the outdoor air sensor as well as the portable central controller, an perhaps the internet gateway if I find one cheaply.

    • Tommy said

      I am about to install several Mitsubishi mini splits in a 1980 second home in the mountains of North Carolina. Ducted is just not possible. Replacing baseboard heat and need AC. The efficiency is a positive. So is the dehumidification. Have been told that the new MHK1 will connect directly to the Honeywell Internet gateway but it will only support 4. Two gateways would do 8. I need 10. Do you know how the MCCH1 works? Could I install 10 MHK1s and an MCCH1 and then connect the MCCH1 to the gateway and control all 10 units from say the Honeywell iPad app? Would love to know about your experiences with the mini splits and particularly remote control of them.

      • Tom said

        I don’t know about the limits on connecting the splits to the gateway… I only have four, and have only installed 3 MRK1’s so far, and decided I did not need the portable central controller (MCCH1); the Iphone app seems to have this covered.

        Note that the internet/iphone app do not support dehumidification mode or vane control – you have to use the remote control that came with the mini split for this. The thermostat does support drying mode, but you have to change the default settings (Installer setup function 146 should be set to 1)

        When I set it up, I connected each MRK1 directly to the internet gateway… even if you can connect all your splits to the central controller, I doubt the internet and iphone app are designed to communicate with the mcch1, since in my application they work fine without it. I also don’t know if the central controller would connect to the gateway at all- I don’t see any reason they would have built in this functionality.

        Hope that helps.
        On the bright side, you can get the gateways for $80 or so each. The MCCH1 costs $160, so three gateways will cost you the same as you would have paid for the MCCH1 and a gateway. Assuming you have a smartphone, that is.

    • mjw said

      I have 2 Mr Slim split systems:
      1) PKAA36FA wall mounted air handler + PUZA36NHA condensor
      2) MSZA17NA wall mounted air handler + MUZA17NA condensor

      I would like to be able to control these from my iPad.
      Tom – Which parts would I need to buy to achieve this? Do I only need
      to connect 1 MIFH1 to each air handler as well as a single Honeywell redLINK internet gateway available?

      Also, I hope I am wrong, but is the MIFH1 battery powered (so you have to regularly change batteries). This link mentions batteries:

      Click to access MIFH1_Receiver_MRC1_Cable_Submital.pdf


      • Tom said

        You are right; you will need 2 MRK1 kits, and a gateway.

        As for batteries, it’s only the mrch1 remote controller that needs batteries- the mifh1 wireless receiver is powered by the air handler unit. I’d expect to change the batteries about once a year or so.

  3. Peter Landis said

    Have you been able to hookup the MCCH1 with the redlink gateway. I have a wall mounted Mr. Slim just as you shown and also already have a closet mounted Mr Slim unit that already has the MCCH1 setup. What I would like to do is install the MCCH1 to the wall mount unit. Then get the redLINK internet gateway to hook up both AC units so I can control it remotely. Though I do not see any instructions on how to hookup the MCCH1 to the redlink internet gateway and was wondering where I can find this info.

    • Tom said

      There weren’t any instructions that I could find. Eventually I figured this out:

      You have to hit the “connect” button on the MIFH1 wireless receiver (shown in the last photo above) to put it in connect mode (green light flashing), and then the button on the bottom of the gateway. If your gateway is set up with TotalConnectComfort website, you should see the thermostat appear at this point. Hit the MIFH1 “connect” button again to return the wireless receiver to normal mode (solid green light), and then repeat for the second unit.

      • Mallox said

        So Tom, from what I can understand you don’t need the Mitsubishi MRCH1 thermostat. You can connect the receiver MIFH1 directly to your Redlink gateway. So you could just use a phone with an appl. or any other Redlink thermostat to control your Mr Slim?

      • Tom said

        It seems like that may be the case. I have not tried it yet. One thing the thermostat is useful for is programming a schedule… you can’t do that online or via your smartphone as far as I know; the website only allows you to select heat/cool/off and temperature setting or allow it to follow the schedule in the thermostat.

        I do plan to experiment with this, out of curiosity, but it’s mostly a moot point, since I don’t think you can buy the MIFH1 without the thermostat.

      • Tom said

        Update: I just tried to connect an MIFH1 to the Redlink gateway without using the MRCH1 thermostat. It did not work, so it looks like you need the whole kit for each unit.

  4. D R Lapin said


    Does the MHK1 remote actually contain its own temperature sensor, or does it rely on the one in the split’s evaporator itself? Or does it use a sensor in the (extra cost) MRCH1?

    I have an MSZGE09NA split, and it doesn’t even come close to maintaining a consistent room temperature. I can set the remote for 78 degrees, and when the sun shines on the outside wall behind the evaporator, the room temperature drops to 65!

    I thought these evaporators were supposed to read the return air temperature, but it seems like that’s not enough. It really needs a less biased opinion of the actual room temperature away from the evaporator itself.


    • Tom said

      I’m surprised that you’ve had such bad temperature control performance. Are you sure your unit’s i-See function is on, and the eye is operating? That’s what it uses to read the temp of the rest of the room.

      The MHK1 kit contains the MIFH1 wireless receiver and the MRCH1 thermostat. While I don’t think the MIFH1 has a temperature sensor, the thermostat does, so there is no extra expense.

      • Samsung said

        Mr. Tom, how can I do this with a samsuong vivace?

      • Tom said

        No idea… I expect every manufacturer is different.

  5. Sean lane said

    Thanks for this page. I am a computer guy at heart and I cannot believe that the split unit manufacturers don’t create their units with an onboard wifi chip to control this. I could design a chip to do this for about 18 bucks in cost. Having to pay 269 for each unit controller and having to connect this to a proprietary Honeywell controller that is connected to a wifi router is ludicrous. Are you listening Mitsubishi, Samsung, et al?

  6. Greg Hadfield said

    I’m going to be running a 6-head units off of one Mr Slim MXZ-8B48NA compressor. I will run the Redlink Gateway off of my router, and use the MHK1 wireless thermostat. I understand that each head unit requires a MIFH1 transmitter that is installed in the head unit by the 106 cable. I’m not clear on why you need a separate MHK1 thermostat for each Head unit (this seems to be the only waqy you describe getting a MIFH1 transmitter). Does this mean that each MHK1 thermostat you get with a MIFIH1 is dedicated to that head unit alone, or can one MHK1 thermostat run different zones? Is multiple zones only iun the realm of the MCCH1?
    to clarify:
    1. Will an MHK1 thermostat run more than one-zone?
    2. Does it take more than one gateway to run more than 4-head-units?
    3. Is there a way to get more than one MIFH1 transceiver without having to buy a thermostat for each one?
    4. If there is a problem with the running of MIFH1 from a gateway (IE- the iPhone IOS runing different zones), is it because each needs a MHK1 thermostat?
    5. Ca you run it all on an iPhone/Android from just having a gateway (or two), a MCCH1 central controller, and a MIFH1 in each head?

    Trust me, I’ve scouted the internet, and no one else is talking about this that I can find- thus far…

    • Tom said

      The MHK1 is a kit which contains both a thermostat and the transmitter/cable. You will need one of these for every zone.

      1. No
      2. Yes.
      3. No, but as far as I can tell, you can’t buy the transmitter without the thermostat.
      4. Yes… the gateway communicates with the thermostat, and the thermostat communicates with the indoor units.
      5. No.

      You need:
      – 2 Redlink gateways.
      – 6 MHK1 kits.

      • Greg Hadfield said

        A couple of things, Tom. Sorry to stand on your shoulders here to see farther, but I’m pretty sure you know the answer to these questions having run this wireless mini-split system for a bit of time.

        Some more background: I am currently listening to my installer crawl around under my newly bought home as he runs all the piping from the 48NA ( up to 8-head compressor system) to the 6 head units I am using in the house. The heads condenser, and branch boxes will be going active either tomorrow or Friday.

        1. The MRCH1 thermostat seems to be another wireless controller similar to the supplied remote with each head unit. Is the MRCH1 working as a thermostat or is the info coming from the head unit through i-see unit? This makes a big difference in where I mount each MRCH1 unit.

        2. Do the MRCH1 and i-See play together, or are they independently polling the temperature of the room- who take priority?

        3. I received the 6-MHK1 packs with the thermostat (MRCH1) and wireless transmitter (MIFH1) in the same box- are they dedicated wirelessly to each other, as I certainly don’t want to mix them up if so.

        4. I received what seems to be a different connection cable between the Head unit and the wireless transmitter (MIFH1).the nomenclature was MRC1 cable, and has the black 5-pin that hooks up to the wireless transmitter (MIFH1) but instead has a red 5-pin end that mates nicely to the head unit without disassembling anything beyond pulling the large white cover off the head unit and opening a door on a grey control box on the low right side of the head unit, which reveals the red receptacle and really could be accessed without even opening that door. I have pix of it all and would post right here, but not sure that is allowed.

      • Tom said

        1. There is an installer setting on the thermostat which allows you to choose if the system uses the temerature reading at the thermostat or from the i-See. Instructions are in the manual.

        2. I believe so, but have not tried it.
        3. Don’t worry about it. You link them during the installation phase. Basically only one wireless transmitter can be in “connect” mode at a time, and the thermostat you turn on while it is in connect mode connects to it.
        4. I’m guessing you have different indoor units than I do. Why don’t you upload your pics somewhere on the web (Flickr or the like) and post a link here.

      • Joe said

        I too have a 6 unit Mr Slim installed about a year ago. I love the system and the efficiency, but would like to be able to control it remotely. I have 6 MRCH1, a external temp sensor & a central remote installed. I bought the RedLink Gateway, read several installation manuals and tried connecting it, no luck! My concern/question is, if I link each receiver to the gateway, will that interfere with its current network function?

      • Tom said

        It’s possible that the reason you can’t link your gateway to the units is because that are already linked to the remote, since I have not yet heard from anyone who has both.

        On the other hand, I noticed that when I was installing my gateway, I could only have one unit in connect mode at a time, and when I tried to put multiple units in connect mode it did not work. That could be what’s happening to you.

        Are you following this procedure to link the gateway and the units:
        1) Put first unit in “connect” mode by pressing the connect button on its MIFH1.
        2) Press the connect button on the gateway.
        3) Return the first unit to normal mode by pushing its MIFH1 connect button again.
        4) Repeat 1-3 for each other indoor unit (up to 4)

        Note that the docs say that you will only be able to connect 4 indoor units to each gateway. If you want to hook them all up you’ll probably need a 2nd gateway.

        If it does turn out that you can’t use both the gateways and the central control, I’d just sell the central remote on eBay and use the smartphone app. Who needs a central remote when you can control all your units from every computer, notebook, and smart phone in the house (or elsewhere?)

        Please let us know how it works out.

      • Joe said

        Thanks for the quick reply. The Central Remote I’m talking about is a Honeywell Model REM5000R whichever allows limited control of all the units and displays the outside temp. The install instructions indicate it can be RedLink connected, so my thought was to connect it, and three of the indoor units. My assumption was that I could control the unlinked units through the REM5000R. It may be that the indoor units can’t be connected to both the gateway and the REM5000R, but then why would the instructions indicate they can?
        I will try the process again soon to see what happens and let you know the outcome.

  7. arri said

    Tom, thank you so much for answering all of these questions that should have been in a manual!

    I was wondering if you are aware of any reason why the MHK1 might have trouble with a non-inverter type Mr. Slim? The promotional materials suggest it’s exclusively for inverter driven units.

  8. MoS said

    If, like me, you have a single head Mr. Slim unit, think carefully before you go to the thermostat unit. You have 2 choices when setting up the thermostat – residential or commercial. If you pick residential, the unit is NOT programmable – you get what the factory decided you should have. If you pick commercial, you get only 2 (user definable) time settings – “occupied” and “unoccupied,” plus a SINGLE weekend setting. You must set both heat and cool temps for each of the two times. This is not very useful and only a slight step up from the remote control, fortunately the install (once you’ve seen the pics here) is not difficult.

    • Tom said

      MoS – your information is not correct. I have successfully programmed my thermostats in both Residential and Commercial modes, and there were four available time periods in both modes. Perhaps you are using an older version of the thermostat.

      • MoS said

        Then there are different versions as well, because I was on the phone with Mitsu support, who verified that “residential” is not programmable (the display reads “Locked”) and that in commercial mode there are only two time periods (in weekly, M-F mode). I bought and installed the unit last month.

        The unit I have is an MHK1, “For use with P-Series NHA4 systems, SEZ-4/SUZ one-to-one systems, SLZ/SUZ one-to-one systems, MXZ-B multi-zone systems, MSY/MSZ, and MFZ indoor units.”

      • Tom said

        It sounds like we’re using the same mhk1. You can find the specs of the one I was using here:

        It seems strange that there would be two mhk1’s that operate differently, but my only other explanation s that Mitsu support does not know what they are talking about and you need to change your installer settings to get yours to work properly.

        Instructions to change the installer settings begin on page 5 of the installation manual:

        Settings #136 (Commercial/Residential) #138 (Programmable), and #148 (Schedule format) seem to be the ones that are relevant. And maybe 160 or 162.

    • Eddy said

      I’m also curious about this. I read another review where it was stated that there were only two available times in the residential settings. Wake and Leave. Thanks for any clarification.

      • Tom said

        All I can say is that I have 4 residential or 4 commercial settings on all 4 of my thermostats. I bought them over the course of about 3 months on eBay from 2 different sellers.

        Residential settings are wake, leave, return, sleep. commercial settings are occupied 1, unoccupied 1, occupied 2, and unoccupied 2. I also can program either in 5-2 or 5-1-1 weekly formats.

  9. Greg Hadfield said

    So after playing with the MHK1 wireless thermostat, the MIFH1 wireless transceivers, the MCCH1 central controller, the MOS1 wireless outdoor temp thermometer and the remote that came with all of the 6-heads I am using, here’s a few things I have learned:

    The naming of each zone is controlled by the MHK1, and will register on the MCCH1 as that name when toggling.

    When pairing the MCCH1 to each MIFH1, you must hit the button once on the MIFH1 connect to institute a connection, signaled by the green diode going red/green at the same time, tell the MCCH1 to connect, the red/green on the MIFH1will change to a rapidly-flashing green, then go to a slower-flashing green, THEN the connect button again on the MIFH1 to bring it back to a solid green. If you don’t you will have no luck connecting other heads in the group.

    When connecting the MOS1 outdoor sensor, you must do all of the same things you did for the MCCH1 in order for each head unit to have external temp and humidity.

    The MCCH1 is great for changing settings in other zones, but that seems to be about it. No control of fan, vane direction, etc…

    Next, I play with the Redlink gateway when my internet comes back up.

    Anyone know of another source of this type of info on this system, as the Mitsubishi info is way lacking, and I’d like to read more about the Redlink system as a whole- to include iPhone and PC support.



  10. Greg Hadfield said

    So now playing with Redlink enabled system I installed on 6-head units, and All I can say is- VERY limited control of these units from the iPhone, the PC, or even the MCCH1 master home unit.
    1. You can turn on and off each head unit, and set it for when it will revert back to its native schedule you programmed from the MHK1 thermostat.
    2. No control whatsoever on fan speed, vane direction, etc…
    3. No control of dehumidify.
    4. I can’t even begin to describe the lack of scheduling.

    Now, I’ve used the same program ( Honeywell’s total connect comfort) with my previous ducted HVAC box system that had AC and heat together, and it started out very limited but firmware upgrades to the wireless thermostat (see my review and the model at )
    and teh iPhone/PC apps made it so very useful in that I could do all that the thermostat offered from a remote location.

    C’mon Tom, there has to be other websites that are talking about this system, and I figure I would play S.I. Newton and stand on your shoulders (you playing Copernicus or Galileo) to see farther…the info on the Redlink system with Mr. Slim is NADA!


    • Tom said

      AS far as I know, this is the only website talking about it… there was nothing at all when I started to do my research about this in February (2013)

  11. Lynn said

    We have 2 MUZ/MSZFE09NA units (one in each office). Now I’m just a comsumer but why would someone manufacture and sell a unit that can’t even sense the temperature and turn itself on and off. I feel we were duped by both the company that sold and installed the units as well as Mitsubishi.
    I would NEVER recommend.

    • Tom said

      I think you misunderstand how the units work; they are different from older models, which only had two or fewer compressor speeds. These operate at any spped, and the lower the speed, the more energy efficient they are.

      They are constantly sensing the temperature and adjusting how hard they work accordingly. If the temperature is at the desired set point, they are only on in the sense that they are monitoring room temperature and perhaps operating at a very low level to maintain it.

      So while it’s true they don’t turn off when the temperature reaches the desired set point, what they do is better. It also means that you get less blasts of extremely cold air, and get a constant cool breeze instead.

  12. Greg Hadfield said

    after a few weeks with 2-Redlink Gateways running 6-head units on what appears to be re-packaged focus pro thermostats, I have hit my intellectual threshold concerning the limited internet program-ability of these units. All I can do is turn them on to cool, heat, auto, and off, and change the current temp settings. This is not very useful in the current configuration, as as I’ve said before in previous posts, the Honeywell wired thermostats that use the wifi option are eminently tune-able on a weekly schedule with 4-time settings.

    Has anyone ventured into the Prestige thermostat territory for these head-units?

    There has to be a better system for the Mitsubishi Mr. Slim set-up, as it has so much in the way of connectivity and energy-saving efficiency but very little for the remote aspect.



    • activescott said


      I also have a two MSZ head system that I’d like to connect to something like the Prestige. I’m not sure if it is possible to connect to a Prestige yet or not.

      Let me know what you find out and I’ll be sure to do the same.

  13. Norm said

    I just installed a MHK1 in my bedroom. The connector was found where Greg Hadfield had stated. The hardest part was getting the cover off after removing the 2 screws. The top portion would not release until I press down along the top back edges.

    I thought the thermostat would completely shut off the unit when the room is not occupied. However the fan continues to run. I don’t suppose there’s a way to turn the fan off other than turning the unit off (which defeats the purpose scheduling).

    Just how much energy and dollars does the unit draw? I only need the room heated or cooled about a couple of hours in the morning and night. Seems like waste of energy for my use.

    • Tom said

      I think the unit draw very little when not actively cooling, but there is an installer setting which enables an off mode after a certain number of hours, but I have not found a way to turn it off totally and then turn back on again on a programmed schedule. That said, given that it is very efficient when operating in a low power mode, it could actually require more energy to turn it totally off and then back on, requiring it to quickly cool or heat a room. The point of a variable speed unit is that it is extremely efficient when operating at a very low level.

  14. Does anyone know what this “Mitsubishi Wifi Adapter is? I don’t see anywhere you can buy it:

    • Tom said

      Looks new, and tres cool.

      From the shape of the connector, it looks to me like it replaces the REDLINK adapter and the redlink gateway and so should allow you to control any number of units via the web or smartphone app, given suitable software.

    • scottwilleke said

      Looks like it isn’t necessarily red link. See the “Mel cloud” links from that page. One concern is that the app in the App Store ( ) appears to be no longer be updated – since ~2010??

      • The thing is, I can’t find it sold anywhere online.

      • Tom said

        If I had not already installed the thermostats, I’d contact a Mitsubishi distributor HVAC supply outlet.

      • Jana said

        I think MelCloud is the app to watch (see, rather then Mezo. The setup requires the installation of a small WiFi device (MAC-557IF-E) into each wall unit, which device is smaller than the wifi receiver that comes with the MHK1 kit. MelCloud was deployed in France and the UK and the iTunes app was updated as recently as January 17, 2014. There are a couple of videos (in French) on YouTube that show how it integrates nicely with any WPS router and the extent of available controls. I suspect, however, that Mitsubishi’s current deal with Honeywell (re Redlink) prevents or makes less worthwhile/urgent the deployment of MelCloud in the USA… for now anyway.

      • Jana said

        I would be a little wary of ordering the MelCloud WiFi receiver from Europe (which can be found online in a few places, e.g., as I read it only works on certain European models — see page 32 of file:///Users/Jana%20Mansour/Downloads/MELCloud+User+Manual+Europe-webb.pdf

        That said, the French video I saw says the receiver connects to the red connector on CN105 or CN92. CN105 is the same red interface that is available on MHK1-compatible US wall units, so it might very well work! I don’t have mini-splits (yet), but would be curious to hear from anyone who tries installing the MelCloud device.

  15. Hey Tom, now that I have you here… Do you know if the indoor units can be retrofitted for use with external thermostats? We currently have a “Nest Thermostat” that is amazing and has awesome wifi/smartphone capabilities. The thing is, it requires standard 24vAC wiring (not sure if the mitsubishi heads can integrate). Here’s the nest compatibility blogpost:

    Any thoughts?

    • Tom said

      I think it is not currently possible to control these units without a REDLINK thermostat (or the WiFi controller you found). Nest is cool, but does not operate in either of these modes.

      Of course, it might be possible to find a port on the control board that corresponds to the standard thermostat control wires you find on most units, but that is way beyond my level of technical expertise.

      • Thanks Tom. You appear to the worldwide authority on Mitsubishi mini split thermostats… it was worth a shot! Thanks again.

  16. Greg Hadfield said

    SO still working with the Neanderthal Redlink System, and having to adjust day to day because the only place to adjust weekly is on the MHK1, and it is 5-1-1 (Mon to Fri-Sat-Sun). Hoping to see the Melcloud open some more doors. Still haven’t played with the Prestige- anyone else?

    Another question- My stacked unit, a MXZ 8B48NA is quite noisy in heat pump mode when the temp goes down- I can hear it through the house- is that other’s experience. Almost sounds like pistons and the spinning of fans. Went out and sat on the unit to see if it was a loose mount, no real change.


    • Tom said

      Although I have split units, not stacked, they are crazy quiet. You have to see if the grass is moving or feel the breeze to tell if they are on, even if you are right next to them. So I’d guess there is something wrong with your stacked unit.

      • Greg Hadfield said

        That’s in the heat pump mode, right Tom? My AC is whisper-quiet.


      • Greg, mine was making a noise, but it ended up being the grade on the back of the unit. It was bounding off of the back. Feel around the unit and see if you can make the sound stop.

      • Greg Hadfield said

        Nothing loose- still the same winding, compressor-like sound that gets louder with the amount of load on it. Thanks Max, I really don’t want to deal with repair, but the noise has always been there since install, it’s the fact we are getting into the colder days here, so it became an issue.

        Any other input would be much appreciated- the unit is right next to the house so it is very apparent.

      • Tom said

        Yes, my units are whisper quiet in both modes.

  17. Ricardo said

    Dear, Tom
    We are developing an indoor growing system at the U of Arizona and we have decided to use a minisplit as the cooling source. For our application with need two different temperature set points and we need the minisplit to change between the set points automatically. For example we need the system at 77 F for 18 hours and then we need the system to switch to 60 F for 6 hours and then back to 77F after that. Is the Mitsubishi 24000 BTU with an external thermostat capable of doing this, if so which external thermostat do you recommend?

    Thank you very much

    • Tom said

      Yes, the Mitsu mini-splits with the added thermostat I describe in this post can do what you want. They can handle up to 4 heat settings a day, but it’s easy to use only two.

  18. Ricardo said

    Hi Tom, Do you know of any other minisplit brand that can accomplish this, using a external thermostat?
    Thank you again

    • Tom said

      As for selection for heat pump, I’m not an expert. I just went for the most efficient model available at the time (High COP and SEER.) I would be surprised if there were any brand of minisplit that did not have the ability to be controlled by a programmable thermostat… many are probably packaged that way.

      Given Arizona’s dry climate and plants’ need for humidity, I’m surprised that you are not using an evaporative cooling system (swamp cooler.) If you don’t want the extra humidity, there are even evaporative cooling systems that don’t add humidity: Either is far more efficient for cooling than the most efficient heat pump (although the heat pump can also heat efficiently.)

      • Ricardo said

        Dear, Tom

        Thank you very much for the information, I have emailed several minisplit manufactures and so far only mitsubishi and YMGI (i can not find info on how to do it) can have a programmable thermostat, Fredriech also has an option but it can not do what i want. The plants inside the indoor growing system produce high levels of transpiration, increasing the relative humidity in the chamber, for this reason we need to de-humidify the system, Also the system is equipped with CO2 supplementation and using a evaporative cooling will waste a lot of the CO2.

        Thank again

  19. Ricardo said

    Dear, Tom

    I found that aircon is a mitsubishi brand, it is not the Mr. Slim, do you know if this model of mitsubishi has the capacity to install the external thermostat?

    Thank you very much again

    • Tom said

      I don’t know anything about aircon. The CO2 injection makes sense as a reason for a HP.

  20. Norm said

    I just noticed I’m not able to access installer setup functions 101 to 128. Are these functions something I should mess with?

    • Tom said

      I’ve been unable to access them either. They seem to be functions which have to do with the communication between the thermostat and the wall unit (i.e. what sort of vanes does it have) which is why I suspect they are not accessible to installers. I think it would be nice to access them, since there is a chance they might allow us to control the left-right vanes from the thermostat. That is the one function of the remote that I’ve been unable to access from the thermostat.

      If anyone knows how to change these settings, I’d love to hear about it.

  21. Will said


    I recently had 3 indoor units installed MSZ-GE09NA-8.

    I am upgrading my thermostat for the supplemental/backup oil heat in my house to a programmable thermostat. I am wondering if i can somehow get these to be controlled all on the same system.

    I know a few people have mentioned the redlink stuff. Is it possible for a prestige thermostat to communicate with the other thermostats you need to install? Would they just see them as separate thermostats that the prestige could then set, allowing then those units to set the heat pump?

    I am not as concerned as other about getting the internet gateway for control, but i would like to be able to use the system to control both systems, one as a primary heating source and one as a auxiliary.


    • Tom said

      You can control all your Redlink thermostats (The Prestige and the ones for the Mr. Slims) with either the central controller (MCCH1) or with the smartphone app/web portal using a Redlink gateway. I think the gateway is the better option if you have a smartphone because it’s cheaper and allows you to control the thermostats when you’re not home.

      • Will said

        Forgive my ignorance I am new to this whole homeowner thing/heating equipment. Learning fast.

        So on my redlink gateway/app It will show up my main oil boiler thermostat that I will add along with each of the heat pump ones, plus any additional sensors i add (outdoor, multiple indoor, etc.). I will then from the app be able to set profiles on how to handle stuff like temperature thresholds and on/off control of each?

        The temperature and controls for each heat pump will not be available on the main prestige unit I will install however.

        Do I have this correct?

        Does the redlink gateway app allow you to set commands based on outside temperature? Like for example I would have the heat pumps be the sole heat source if the outside temperature is above freezing. The reason being they are not whole house units, only in main living areas. So when the temp is below freezing the oil heat still needs to be on, just set low. I was not sure how robust the online app was in handling things.

        Thank you for keeping up with this blog and questions, it really is the sole resource on the web right now.

      • Tom said

        Yes, the app/web portal will show all the thermostats both boiler and heat pumps. Sensors are linked to the thermostats, not the gateway. They are displayed on the thermostat itself and on each thermostat screen in the app; I don’t know if there is a limit to how many sensors per thermostat, I only have the outdoor temp & humidity sensor both of which are displayed on my thermostats and online.

        There is no advanced programmability – you can just set mode (heat/cool/dehumidify) and “follow schedule” or set the temp manually. I doubt the central controller has more capability than that but read the manual online- I have not checked.

  22. Will said

    Did anyone ever find what each of the 5 conductors coming off of the CN105 port are? Like a diagram showing 1 being the fan, temp, etc.

    I am wondering how easy these control wires would work with a less proprietary system.

    I am trying to chat with customer servide but they are less than helpful.

    • activescott said

      I also am interested. However, I don’t think it is that simple. From what I understand, generally these type of devices are a TTL serial protocol ( However, I haven’t been able to find any info on the mitsu equipment except some protocol converters that will talk RS-485+modbus but that isn’t cheap and doesn’t get you quite to “compatible” with most systems.

      Let me know if you figure anything out.


  23. SimonS said

    I emailed Honeywell and Mitsubishi about this also – it would be a fantastic sales pitch for both of them if systems interacted nicely. I have a 4-way Mr Slim heat pump with Redlink MHK1 – and i have hot water baseboard for backup/emergency heat (which we need right now in NJ given the temperature) – I am probably going to use Honeywell Redlink Truzone for controlling this. In my ideal world (and to save energy) I would use the heatpump until the outdoor Redlink sensor dropped to 25/30F and then have the hot water baseboard kick on instead. This would fire the boiler and keep any pipes from freezing. This would be simple and elegant – and I think a lot of people would jump at this kind of solution if it existed.

  24. Joe Baker said

    My dog woke me at around 4am to go out. When I went downstairs I noticed that it was warm and that the unit in the living room was blasting heat out. I checked the thermostat and found what you see in the picture at:

    Please note that I have this zone programmed as follows:
    Wake – 6:30am – 5:30pm – 72 degrees
    Leave – unused
    Return – 5:30 – 9:30pm – 73 degrees
    Sleep – 9:30pm – 6:30am – 66 degrees

    Also note the “Recovery” indication on the top left of the display. What is that? How’s that get programmed and is that what causing the system to malfunction? If so, how do I turn it off or change it’s settings?

    I did check the other zones and didn’t find this on any of them.

    • Tom said

      I could not see your pic, but what’s probably happening is that these units anticipate schedule changes. They operate much more efficiently at low output, and so when it sees the higher heat setting at 6:30 am coming up, it starts heating the room in anticipation. I’m not sure what factors are at play here, but if you were experiencing the same cold snap as most of the country at the time, the unit may have decided to come on even sooner than usual because it needs to work harder to achieve the desired temperature when it’s cold out.

      The setting in question is #150 “Optimal start” The factory default is 1/On. You can change the installer settings by pressing and holding the “fan” and up arrow buttons simultaneously. See pages 5-9 of the manual: Page 9 says “(Setup Function 150):Allows the remote controller to “learn” how long the equipment will take to
      equipment will take to reach programmed temperature settings, so the temperature is reached at the scheduled time”

      If you to turn this feature off, you’ll probably end up with more energy use overall. The unit will come on flat-out at 6:30 am and probably take an hour or more on cold days to get to 72 degrees, although you might be able to compensate by programming your schedule for only gradual temperature increases.

  25. Tom said

    There’s an excellent article on the advantages of minisplits in highly insulated houses by a green building professional on Green Building Advisor:

  26. […] discovering the limited programability of the factory controller for my Mitsubishi units, I installed the Honeywell thermostats in addition to a thermostat for my boiler which I now control them all through the same […]

  27. Greg said


    This is great information and has given me the confidence to buy some MHK1 kits – without this page I’m pretty sure I would be left with some useless equipment.

    In the manual for the MHK1, it seems to imply you can set the temp lower than the given remote (50F) – is this true in practice? I would think it is bound to the unit(s), but there are elements to controlling these systems where Mitsubishi seems to have thrown logic out the window.

    In related terms, both the article you linked and a comment you made about turning them off for the day may not save that much energy is something I’d like to hear more thoughts about. Where I am it’s just shy of 24 cents a KWH, and while I am still hopeful it will beat my oil solution some of these units exist only in the winter months to prevent pipes from freezing while others go from 59 F while we aren’t around to the 65 F we feel is comfortable while in the room.

    Your input on this page is awesome, thanks again!

    • Tom said

      On the minimum temp, I just tried it, and could not get the temp to go below 50. There is an installer setting on the thermostat which allows you to set the minimum temp, but I don’t know if you can set that below 50 or not. I’m sure mine is set at 50 b/c I’ve never messed with it.

      In terms of turning them off, Marc Rosenbaum did say in this article that these pumps can draw a surprising amount of power in standby mode, but keep in mind he’s working on Net Zero homes, so every kWh counts. Mine have not yet been installed a year, but my best estimate is that I use about 1/2 of a kWh per heating degree day (HDD) to run the pumps- so if my thermostats are at 70 and the average outside temp is 20 (i.e. a high of 30 and a low of 10), that’s 50 HDD or 25 kWh – or about $6 at your electricity prices ($4 at my prices.) In the summer, I was using less than 3 kWh per day for A/C and defumidification – too little for me to really be sure without direct metering.

      One caution- don’t turn them off if it’s snowing. I had one in my bedroom which I had programmed to turn off during the day, and we got a heavy, wet snow which got into the heat exchanger fan and then froze. I had to turn the furnace on that night until I could go out and clean away the frozen snow the next day. One of my pumps which had been running the whole time probably lost efficiency as ice built up on the heat exchanger (I cleaned that one off with hot water), but at least it was still working.

      • Greg said

        That’s much needed advice I haven’t found in scouring other regions of the Internet, thanks. Got 3 units (2 x FE18NA and 1 x FE12NA) installed last week and had high expectations which they are meeting/exceeding.

        My prior message I was pecking at a tablet and as a result I wasn’t too terribly clear – I meant that my included remotes with the units only go down to 59F, it’s great to know that the MHK1 will let me go down to 50F (or at least get to the programming to set it to start at 50F).

        The FE18NA unit in the detached in-law apartment will be used as an AC rather often in the summer but as a HP in the winter mostly to keep the pipes from freezing so I will have it on all of the time – I could probably make up the cost of the MHK1 for that unit by being able to set the temp down 5 degrees.

        Anything else you recommend on the programming side when I get and install the units you recommend setting?

      • Tom said

        It’s worth getting a Redlink gateway and an outdoor temp humidity sensor so you can control them all via the web or smartphone. It’s just cool, and not too expensive. If you have a furnace or other form of central heat, get a redlink thermostat for that too. I never thought it would be a big deal, but with five thermostats in my house, it’s great to be able to control them all in one interface. I posted a screenshot in the article here: (scroll down, it’s towards the end)

        You can save some $ and buy all the extra stuff in a kit. This is the one I bought: Honeywell Yth6320r1114 Wireless Focus PRO Wifi Thermostat Kit with Gateway

      • Bill said

        How much did you spend on your whole setup?

        Does the redlink give you control to set profiles? ( Like turn off oil heat if above x degrees)

        I want to be able to integrate my heat pumps to the same system, a lot of thermostats have heat pump inputs but not being able to find out what that 5 pin control wire conductors actually are makes it impossible to even attempt to setup.

      • Tom said

        $15.5K, $13K after utility rebate, so we’re looking at a 5-10 year payback, assuming you ascribe no value to the fact that I now have A/C. I prefer to think of it as A/C that pays for itself.

        The app/web interface do not allow setting profiles. Several people (including me) have complained about this in the comments above.

        I agree having 1 thermostat per hp is frustrating… that’w why I recommend the web/app despite its faults.

  28. Jared said

    I recently installed a MSZ-FE18NA series heat pump, but the unit doesn’t do a wonderful job of keeping the room an even temperature. (Note: This unit DOES NOT have the “eye”, and it’s installed in a sunroom where temps vary widely)

    All I want is to be able to maintain the room at 70F at all times. I don’t care about redlink, scheduling, etc.

    I’m concerned that if I buy this thermostat to get a more accurate temperature reading, that it won’t be able to communicate to the receiver if I mount it up in the attic. (I don’t want to be able to see the cable for this receiver, so I plan on running the cable into the attic with the lineset)

    It’s only a distance of about 18′ feet from where I plan to mount the new thermostat, but I haven’t seen any distance limitations mentioned…anybody know?

    • Tom said

      It will work 18′ away easily. I have one that is about 50′ away from the heat pump on another floor.

      Note: I had to change the installer setup value #173 to do this, but the default setting will work for your purposes.

      (From page 7 of the manual:
      Setting #173 – Sensing Location.
      Default: 1 Sense at Remote Controller
      0 Sense at Indoor Unit)

    • Greg said


      I have two MSZ-FE18NAs, the one in a larger area also has trouble keeping up. I strongly suspect it’s the auto function that is rather poor at keeping the temp at the correct level, especially when it is cold – vary rarely does it go beyond quiet mode even when it needs to. Setting the fan on high keeps the temp at a better level but it’ll blow past whatever temp I had on the remote.

      The other FE18 unit seems fine, but it’s placed on a knee wall (about 3 1/2 feet off the ground) and is placed in an area where temps are stable. That unit is in a detached in-law apartment, and while I’ll have to double check on the head unit, I’m 300 feet away and 3 solid walls between the unit and am pretty sure it’s picking up my changes on the remote. They advertise ’10k square foot radius’, which would be, errr, what, about 2,500 feet away? I’m sure it’s line of sight sans walls though.

      My MSZ-FE12NA also doesn’t seem to have the problem you describe, it’s either the placement of the head unit or the all magical eye, I can’t tell yet.

      I just finished a couple of minutes ago installing an MHK1 unit on each of these, I’ll loop back to you in a week and tell you if it does a better job of the problematic FE18 – on that unit, as opposed to my other two, I set temp readings on the remote.

      I’m going to post right after this on the slight differences for installing this kit on the FE18. Good luck!

      • Greg said

        Eh, don’t look at my math, I did read somewhere ‘it will work for 10k sq. feet!’ which isn’t a standard measurement. I’m assuming they are talking an up/down axis as well (z axis?), so 5k diameter or 2.5k from the unit.

        Again, that’s probably optimal conditions, a.k.a. you are 2.5k feet from the receiver. In space. 20 million light years away from any entity generating EMI, etc. etc.

      • Jared said

        Tom/Greg – Thanks for the quick and helpful responses.

        Overall I quite love this unit so far! (on day 2 now)

        It’s whisper quiet outside, except I have some noisy vibrations getting through the wall mount bracket and through my exterior brick walls. Funny how from 3 feet beside the condensing unit you can hardly hear it, but in the house from 20′ away I can hear it whirrin’ away. I’ll try my hand at remedying this soon…

        Greg, very funny you mention it not keeping up on “auto”. I’m noticing the same thing – today my room temp has been about 71F all day on auto, and now that night has hit and our outdoor temp has dropped to -1F, my room is 60F!!

        Why does auto mode never seem to ramp up when the demand calls for it? I’m seriously hoping the remote t-stat fixes this issue, because I don’t want to be babysitting the Fan-Speed button every single day.

      • Tom said

        Jared… I think your problem is not the thermostat, but simply that heat pumps lose heating capacity at low temperatures and your room probably has less than adequate insulation. At 1F, hyperheats have lost 5-10% of their heating capacity, and the heating requirements of your room are much higher. Since you said it’s a sunroom, I’m guessing a lot of glass and maybe not so great air sealing. If it’s a former porch, there may not even be any insulation under the floor. If I’m right, you should probably be impressed that it’s still 60.

      • Jared said


        When I sized the unit and performed load calculations I took all this into consideration. You’re right – lots of glass, imperfect seals, and a semi-open crawl space underneath that isn’t insulated. (Will be soon!)

        The thing is, when I turn the unit fan setting from “auto” to the highest setting, it keeps up. Today is a perfect example: I awoke to -10F temps, and the room was at 70 because I had the fan on high all night.

        So, on one hand I’m very glad it’s keeping up with the coldest weather we’re likely to see around here.

        But for some reason when left on “auto” fan, the unit doesn’t seem to stage up to handle the load. I’m hoping a remote thermostat would help by (at the very least) giving the indoor unit a more accurate reading.

      • Tom said

        I can tell you that the fan kicks up when it needs to on my units with the MHK- I did not use them very long or in very cold weather without, so I don’t know if the Auto fan function was not working as you describe before I installed the thermostats.

  29. Greg said


    Wanted to thank you again for your responses and for this page in general. Having just installed these MHK1 units, I’m pretty sure it conjured up a solid 3 or 4 hours I would have otherwise wasted, not to mention I would have been more prone to breaking these things.

    Initial impressions are quite good, it’s astounding that I can set my units a full 9 degrees lower than the given remote. Next step is getting that Internet gateway you linked.

    Wanted to briefly state some differences installing these on an MSZ-FE18NA unit (sorry, didn’t think to take pictures):

    – I don’t think the horizontal vanes have instructions on the vanes like they do the other units – where they connect to the main unit there are tabs on all of the connections (save for the rightmost one) where you can easily undue the connection – Tom’s finger is on that tab in the picture above, just push it towards the right.

    – Overall, the FE18 is a much easier install – like the FE9 and FE18 the control board is on the right of the unit, but you don’t have to take it out – it’s fully exposed. (One FE18 unit is quite close to a corner, and after fiddling with it for an hour, I’m pretty sure you can’t take the board out without dismantling most of the unit). The control input, like the one above, is red and easy to spot.

    — As a result, there is less movement of other things so you’re really just taking off the cover, control board cover, and 220V line feed cover. (no mucking with emergency switch or magic eye thingie)

    — — Just like the other units listed here, triple check that the power is off, you’ll be tinkering around the 220V lines and they’ll be easy to brush up against.

    • Tom said

      Thanks For the added info.

  30. jmag999 said

    Has anyone attempted to use a MAC-5517IF-E wifi interface in the US?

  31. Calvin Thomas said

    I have been searching for the wifi connection for my mr.slim units. Finall found some information
    Mitsubishi part # = MAC-5571IF-E Login > (your language) >Show demonstration
    Looks similar to REDlink program for american systems.
    still I want the connecitiviry of single wifi network instead.

    • Calvin Thomas said

      Shoot. That was damaged…
      Mitsuibishi Part # MAC-5571IF-E
      “” > login > english > View Demonstration

      • Matt said

        I’m also very interested in the MelCloud option. Does anyone have any information about when it might be available in the US? I have a three-head system, but would be happy to connect to just one unit online.

  32. I wonder if anyone has any idea of price of MAC-5571IF-E

    I found a webpage in europe that claimed 130 (enlish) pounds for this.

  33. I am disappointed in Mitsubishi. It appears to me that melcloud app is blocked in USA. Itunes says it does not exist but if you go onto european mitsubishi websites that talk about melcloud, they tell you to download in Itunes. The strange part about it is tI have itunes open and running on the other monitor when it tells me this.
    So, it won’t download in USA. I supposed I could try a portal to bypass the blockage, but what’s the point? It requires internet access for it to work and obviously, they won’t let it work from USA.
    I am certain it was part of the deal with honeywell to not create competition for redlink. If so, then we got the short end of the stick since with that app and the wifi connection it would be trivial to add domestic home control to many home automation programs. That is what I have wanted and do want, but honeywell, (being a corporate greedy bXXturds) probably made it a requirement to license redlink. Personally, Mitsubishi made a bad mistake (from our point of view) and Mitsubishi Europe is the greatest part of Mitsubishi. If anyone thinks I am wrong in this, please feel free to post your opinion on this and let me see why I am wrong.
    If anyone know any way to get around this (and don’t tell me proxy’s. I want something I can use on any pc, iphone, or ipad that is simple and works), then please let me know. I would love to be proven wrong.

  34. After almost a year of using my units- a 48 running 6-heads, I can say that the efficiency is phenomenal, but the wireless control is rudimentary at best.

    Redlink is a joke compared to the previous Honeywells that I’ve controlled wirelessly, and I use the iPhone/Computer interface to turn units on and off realtime, and set at current temps with length of time for said temp only.

    The real shocks paying $2100 to run this stuff from a phone or a computer, and having it be so primitive. in Its favor, it is reliable, as I’ve very infrequently dropped a connection while away from home.

    time to get more sophisticated, Mr. Slim,

    • Tom said

      Totally agree, Greg, the interface is weak, and $2100 is too much to pay for it. With self-install, I paid about $800 for 4 heads which I thought was worth it.

      • calvin thomas said

        Wel, I may as well reply to some points that have come up since this is the only place that anyone is speaking on these issues.
        1. I just bought 3 redlink MHK1 kits for $140 each from ebay. The seller said he had 9 so he has 6 more left. Supposed to be brand new. I will find out.
        2. i looked at the redink software and the melcloud software and they looked like two versions of the same thing.
        3. I would not count on melcloud becoming available in USA for a long time. Honeywell doesn’t want any competition for RedLink as they try and make it the defacto stardard in the USA.
        4. HOWEVER.. I have read that honeywell has announced an OPEN API for their software. that means that all the software to automate homes can be integrated with it. That’s why I went ahead with the redlink purchase. In a year or two I can purchase a software program that will be 10 times as much and redlink will only be the protocol it is running on.
        I have not seen any mention (I didn’t look very hard) for a method to connect to the wifi connections in melcloud. If I had been able to test it (other then a demo) I may have decided it was “the one” but the redlink should work if some new software can provide some brains to it. And with the internet gateway, any program can connect to it and control it with the API

        So that’s my updates. Please contribute. I want to hear more information.

      • Si Zim said

        Thanks for pointing out the eBay seller with the reasonable MHKs – I snagged another one for myself. I have two larger rooms where the internal (return air) sensors on the indoor units are not working so well. Putting a MHK1 in one room has evened out the temperature control a lot so I will put another in the bedroom. Added bonus is that I have the Redlink gateway etc for my steam heat so I can control it all remotely via my iPhone if needed. Unfortunately the house wont switch automatically to steam heat on frigid days (emergency heat) but this way I can do it fairly easily remotely.

  35. calvin thomas said

    Glad that womwone on thsi board got one (or more). I am waiting for mine to arrive. Probably this weekend.
    if anyone finds software that has been redlink enabled and thinks it is intersting, I am looking to go that route. if the API is opened, it will (hopefully) be the answer I have been looking for.
    I am experimenting a bit with the handheld (remote) controllers as far as how accuratly they control the temperature. I bought my mr. Slims in 2010 to take advantage of the energy discount, and have been limping along on them for all this time. I was so happy to see this post since this is what I wanted to do all this time. I even invested a few dollars on a USB powered and controlled infrared detector and repeater. I never got around to it cause I was kept wanting an integrated official solution and kept waiting.. and waiting.. and here it is. Expensive, but worht it I think

  36. calvin thomas said

    Sorry I can’t see what I am typing. That was supposed to say “:Glad that someone on this board”
    I have a wordpress account and when I reply on this page (in eitehr chrome or IE) , it moves the input lines for my name and email address right into the box for typing the reply. So for one or more lines I have to type blind…. I haven’t found the answer to that. Very Annoying.

  37. […] It took some haggling to get it to that price. I did my research, including finding this site (Adding a Programmable Thermostat to Mitsubishi Mr. Slim Heat Pumps | Clean Energy Wonk) where, ignoring his rebate, he paid a lot more. And that leads to the next part… My number also […]

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