mini split control?

[cadillackid]

has anyone found a good way to control and monitor the operation of minisplit units?

im working on a network of them for my house and am wondering how to control them...
-Christopher

[Steve Q]

I did a little research about a year ago and if I remember correctly many of the mini split AC units are IR or RF controlled. I was planning to use either IR or RF commands sent from Homeseer. My project is on hold for now.

I'll be interested in your results.

Steve Q

[cadillackid]

ahhh so the control part of this project looks promising... it turns out that these mimnisplits... (at least the fujitsu and the mitsubishi) talk in RS-485 from their main control board to their "receiver board".. this just means a cracking of the protocol to be able to read out temperatures and issue it commands...

the Grunaire units have the option for wired or wireless Tstat control and only have 3 wires going from the control board to the thermostat display so im presuming it will be some sort of serial as well... once I get the boards ill be able to see what type of electronics are on each side and gain a better handle on the protocol.. they only use 2 wires for the communications between the outdoor and indoor units... again ill have to look at the boards and see what components are in use...

for my first unit I have chosen a Grunaire 20 SEER inverter heatpump type it uses 410A and varies the compressor speed based not only on the room temperature but on the suction temperatures and coil temp.. that is real promising because by limiting or increasing the amount of air I let the coil have will factor into how much compressor load I get.. these things may just fit perfectly into what im doing with just simply some repackaging of the units... (different cabinet for the indoor unit)...
-Christopher

[cadillackid]

after a lot of work and testing i am Now able to communicate bi-directional with my minisplit inverter units... I am using an ATMEGA328P micro-controller to do so... communications to my Homeseer PC is done via a serial port right now.. and right now it is set to communicate with my companion HVAC automation program directly...

however it would be really easy for me to make my microcontroller follow say the RCS protocol so that a minisplit could be added to your homeseer system using one of the already available plugins...

if enough interest sparks up I might try to build these into a real product and write a plugin for them...

I can communicate with the "Chigo" made Minisplit inverter units... they are sold under the brands of amcoraire,soleus,chigo,Grunaire,TurboAir and probably others...

these particular units are inverter type High efficiency and come with a WIRED as well as wireless remote control.. my device replaces the Wired controller and talks to the unit that way...

I could also build a device that would act as a go-between the wired controller and the unit and allow you to keep the wired controller.. however i'll have to use a bigger processer like an ATMEGA1280 or such that supports multiple pulse captures simultaneously.. the 328 processer is 10 bucks as opposed to 50 for the 1280 processor....

and the AC units are a bit picky so its necessary to use Hardware timers to capture the data-streams....

turns out its not RS-485 after all.. it is just standard 5 volt TTL logic... leave it to the chinese.. Keep it simple...
-Christopher

[cadillackid]

another update.... I am now controlling my inverter mini-split unit using Homeseer and a little VB program that talks to my micro-controller board....

the protocol to the minisplit is really lightweight.. you send 5 Bytes of info to the unit and the unit sends you back 4...

each Byte is bitmapped so you can get lots of info in a small space...

setting a certain bit will cause the unit to dump its current settings back to you kind of as a query...

the units also have a comprehensive diagnostic and error code reporting system.. and the error codes are transmitted over the line as well so you can know if the unit thinks it is failing...


the protocol in my micro controller to talk to my VB program (which interfaces with Homeseer) does not yet follow any real standard.. although I will likely write my VB program as a plugin for HS and allow it to follow the standard thermostat conventions.. however on a minisplit there are parameters that are not needed on standard stats.. such as fan speed, directional outlet "swing".. and also airflow angle for the air outlet...
as well on a minisplit there are more modes than just the standard heat, off, cool or auto... it also has a "dry" mode - which is basicilly cooling with auto fan shut off.. and a Turbo mode which is full cooling high fan continuously regardless of room temperature...

however right now its just nice to be able to have them operated by HS
-Christopher

[cadillackid]

yet another update....

my modified mini's... 2 out of 3 so far are installed and working and are integrated into Homeseer as well... I use my RCS zone controller now only as a means to input setpoints and modes to the system... my little micro controllers talk to the HVAC units via the unit's protocol and then to my HS PC via serial... i wrote a VB program that talks to each unit controller...

I manipulate the room temp sensor on each mini using a dallas digital Pot.. and this allows me to make the mini's temperature "match" the RCS controller so that everybody stays in sync... I also can control temperature swings by what factor I apply to the mini for temperature manipulation...

my dampers are on my Ocelot... in the event of homeseer failure the heatpumps are disabled and the original Gas heat is enabled and all dampers will reside open so that the house wont freeze... basicilly will operate as a single zone system using the setpoint of whichever zone is calling.....

Plus when the weather gets cool or wet enough that heatpumps are ineffecient I have the 95% gas heat that will switch in and operate....

-Christopher

[cadillackid]

just an update to those who might be paying attention to this:

went throuigh a pretty Harsh winter here in ohio with lots of snow, ice, cold, power blips, etc and this thing worked great!

I ran into a couple issues with the split systems themselves.. manufacturing defects in a circuit board, some bad piping in the condensor etc, however the control system did its Job wonderfully.. even down to warning me of error codes coming from the AC unit for the low refrigerant and the circuit board failure......

My energy bills were MUCH smaller than in previous years despite the wickedly cold winter we had here in ohio... and the fact I spent the whole winter home with no business travel which shouldve realy run the bill up.. but it did not.. i amazed..

I ran the system hybrid in tandem with the gas heat.. (not at same time)... the systems switched back and forth depending on heating requirements and outdoor / indoor conditions...

time to move onward to cooling season and get the system perfected for that....
-Christopher

[mmikem]

I've got one of these mini splits under the amcoraire brand. I have put three external controller units (complete units) in this thing and the system isn't even a year old....You having the same sounds like this is a pattern with the China made units. I have a bad feeling it will happen again. Very interested in the controller you have made so please lets not let this thread die...Any Plans to make some to sell? I'm in! thx

[cadillackid]

which boards have you been replacing in your unit? the wired wall controller itself? or the complete outdoor condensing unit?

since I posted last I havent had any more failures on my equipment, but it is pretty clear from the design that these china / korean made units are not the quality we all are used to in the USA...

just rewmember with your amcoraire that they are defunct company now however parts for it can be had for grunaire or turboair and they are the same... is it an 'HX' series unit?

as for my board, right now im working on alpha testing level 2 and putting ethernet on board.. everyone is going away from serial and I want to go away from serial in my HA setup as much as possible so im building a version with an 'Xport' on it and will see how that goes...

we have had a bit of a heat wave the last couple weeks here.. and I purposely pushed the system hard.. let the house get up into the mid 80s ands humid inside before closing up and turning on the zones... amazingly it cooled down VERY quickly.. and then as I got closer to setpoint I backed down the central fan.. as expected the units backed their compressor speeds down to match me where I could then work on the humidity...
these things will run at very low capacity as needed ( using a vibration transducer on the compressor) i was able to see the compressor running as low as 1200-1300 RPM...
my oldest unit likes to maintain a colder coil temperature than the newer ones.. it appears to have the oldest software... looks like they were learning at that point.. it is also my smallest zone so it may be just that I run down lower airflow than it likes but i never get close to freezing its coil....
{remember my mini splits are no longer mini splits, they are transformed to ducted splits}

I will make a youtube video showing how the system works to give you an idea what im doing here...
-Christopher

[mmikem]

I replaced the entire card cage in the outside unit three times. One direct from the "factory" had a direct short across the power. Yes, blew the breaker. The rest of the equipment (inside and out) has been pretty good. BTW, the clock on the inside controller gains 15min. per day. I have had the latest controller in since xmas 2009 (absolutely brand new, and newer firmware version...others were refurbs, no doubt), and so far so good. Going to get up to 107 this weekend so we will see if it holds. When I started the troubleshooting I did find out about Amcoreaire being defunct, and thru detective work found that Pridiom Group had bought their inventory and service organization. I was working with a guy named Allen there and he was fantastic. My unit is an AMS241HX 24000 btu. 2+tons of AC ;-). Its cooling my 800sq ft shop. It does a great job, even after opening the garage door. Its cool again in about 30 min. in 95degree heat. Thanks for the reply Christopher. Please keep us updated on yor board progress!

Thx!

[Steve Q]

How are you handling getting in-warranty repair parts? Most companies will not honor the warranty if something is added to the circuit. Can you provide a photo of how you are adding the "board"?

I am still interested in adding a mini-split system for additional heating/cooling of the upstairs room I added several years ago. But it must be reliable.

Steve Q

[mmikem]

This is a good point. However, when I was having the issues I did, I was not asked if I had made any modifications. They were more than willing to throw hardware at me until it worked. Because of that I now have a spare fan motor and extra card cage. The card cage new is about $600.

I am interested in the board but I would also like to see an IR implementation knowing the board is probably the more robust solution.

I have to admit, as helpful as Pridiom Group is/was, I would probably spring for an additional couple hundred dollars and buy the Mitsubishi system or other "major" brand...I was a little leary of the Amcoraire brand and now I know these units are mass produced in China and branded under a half dozen names by private companys. Buy enough unit? Get your name one them from the factory...

[mmikem]

Forgot to mention, All this support from Pridiom was email and over the phone. I replaced all the parts in the system. This too is unusual for warranty repair! I didn't care, I needed a working system!

[cadillackid]

my board actually connects to a "port" on the indoor board... these units are designed to have a "wired" wall controller connected to them... its not a thermostat per say although it looks like one.. all the temperature sensing and control is still done on the unit's main indoor board...

the wired controller sometimes is shipped with the units, i know for a while amcor and grunaire were shipping this controller with them then later made it an option as many installers just threw this $150 piece of equipment in the trash!!!..

anyway this controller connects to the indoor board via a 3 pin cable... (power(+5), ground, and signal(coms)).. the original controller is an LCD backlighted controller that pulled well over 500 milliamps at 5 volts DC.. I connect my board in place of this device and power it right from the provided 5 volts.. (I pull about 100 milliamps on the serial version and 350 on the ethernet version)....

my board has the capability of turning the unit on and off, setting modes, fan speeds, swing, and monitoring fan speed, room temp, and setpoints..

I have taken my system MUCH further than this.. but thats not relevant in this discussion...

so im not really doing anything there that should void a warranty as it involves no mods to the original equipment of the unit...

now as far as ir.. I do know the global cache GC devices CAN handle the ir codes these require.. However the Ocelot cannot...

the thing to remember about ir with air conditioners is that the ir remotes provided with these typically hasve the set temp, fan speed, louver control, swing, mode etc all displayed on the screen of the ir remote...

this is *NOT* 2 way ir.. what it is that the remote control sends ALL parameters to the unit EVERY button press... so say my A/C is set to cool, 68, medium fan, no swing, louver on low position.. if I simply press the temperature up button to go to 69, it will send to the unit: cool, 69,medium fan,no swing, louver low.... this is how they keep the wireless remote in sync with the unit....

take the remote in a different room.. and mess with all the settings.. set it to heat, 80, high fan, lover up, swing... then walk back out to the room where the unit is.. press the temp up button to take a unit that is running on cool 68 to cool 69.. and bam! the unit will go to heat, 81, high fan, louver up, swing.. because that is what the remote is set to.....

so to do ir you can imagine the number of settings combinations you must retain in say a GC-100 to handle the different scenerios you might want to use to do ir...

my best thought is to write a program to send out the ir that way you can build it in chunks.. my thought is that the ir commands are the same as the wired controller commands that are pulse distance encoded... in a 4 or 5 byte sequence depending on what you are working on....

-Christopher

P.S. the next phase of my project will be to monitor the comms from indoor to outdoor unit and also from Inverter board to outdoor board so that I can get measurements of current pull, compressor frequency etc....

[mmikem]

Hey Christopher,
I was just rereading this thread and I still think the board solution is the best for these minisplits. Looking forward to that YouTube video. Gotta ask again if you plan to commercialize this. If not I'd love to get my hands on schematics, parts list and software. Its supposed to be 104 today and upto 108 by monday. I've got no view/control into my homeseer right now on that system. Ethernet I like cause I've got a tap sitting right by the unit.
Mike