Samsung Heatpump via MODBUS/RS485

I have a heatpump setup from Samsung, using a AE120RXYDEG outdoor unit with a MIM-E03CN indoor unit.

Whilst I’m currently “controlling” the heatpump via the room thermostat (using a Shelly), this only gives me on/off control of the heatpump, with the temperature being governed by water law. I’d like to improve this!

I can see in the manual that there’s some option for demand ratio control via Modbus/RS485. I can also see the wired remote uses RS485 to communicate to the main board, so it should be possible to tap into this.

FR Control(Frequency ratio control) - Display “DR” on wired remote control

This is to limit the maximum frequency of the outdoor unit compressor. (if #5051 = 1 “use”)

Mothod 1 : External DC signal Control uses a DC voltage of 0 ~ 10V (0v = 50%, ~ 10v = 150%)

Mothod 2 : Demand ratio (DR) control through Modbus communication.

At this point I’ve managed to find nobody else who’s done this (via googling) and so this post is really a placeholder in the hope that someone comes across it and can share some info :slight_smile:

One hint/lead that I found is this project, which is doing a similar thing but to a different Samsung controller: GitHub - DannyDeGaspari/Samsung-HVAC-buscontrol: Protocol description of the serial communication channel of Samsung airconditioners.

If not, then I’ll update in the future with my success or failure :slight_smile:

Hi John,

I also have Samsung HP with MIM-E03CN control kit. I’m also thinking about it to make it more smart because the default control is just stupid.

Water outlet mode is useless and wired controller thermometer as well. It has 1C hysteresis and you can’t control temperature curve at all in this mode so you have to rely what you’ve set.

So I’ve bought external thermostat with on/off signal - same what you have. I’ve set hysteresis to 0.2C and this is much better now.

However, still not perfect since I want to control water offset temperature based on outside temperature. I need that above 5C+ outside I need to set flat 45C water temperature and controlled only by external thermostat. My heat lose is pretty low at higher temperatures and have pump running at minimal input with fan almost not spinning is not good for efficiency. Bellow 5 I need it to run by the set temperature curve constantly.

The only possibility is to use Modbus + RS485 converter controlled by raspberry pi for example and program some better logic including maybe some real weather compensation, etc…

Don’t have much time for this so wanted to ask if you have had any progress here.

Maybe I will look at this if I have time but there is very little information available for this.

This thread should help with controlling a Samsung heat pump via modbus using HA