Chromagen Midea 170L Heat Pump Hot Water System - Modbus Integration Success

Finally managed to get my Chromagen HWS properly into HA - I’d previously tried a simple Shelly on/off switch but had some issues with not being able to monitor temperature while it was off.

This is only possible due to the integration work by BrittonA on github here

I didn’t want to use that module style though and thought I’d try the cheapest seemingly suitable module from Aliexpress, found here. I chose the one with ethernet adapter cable and bracket, although didn’t endup using the bracket.

You generally want to follow the steps on Github, but for steps 1-3 do this instead:

  1. hook the EW-11 up to power (5-36V). Connect to its hotspot. you then have two options, i’d try 2a first then 2b if no luck:
    2a. Visit 10.10.100.254 using a browser. You should see a fairly nice web interface:

2b Or use the clunky OEM software “IOTService” to configure. It can be downloaded from an OEM FTP server here, but it was very slow when I grabbed it

3 Now you will want to configure your wifi credentials. Modify mode to ‘STA’ and enter your SSID and password. Reboot the stick and check your router to make sure it has connected - now is a good time to give it a static IP address using your router controls. Don’t proceed until you have a stable wifi connection - you will be able to visit the EW-11 config page by entering the new static IP address in your browser.

NOTE: the reset button on the web portal doesn’t reboot the device, it resets the settings. Go to ‘Others’ to reset the hardware.

4 Configure the Modbus/RS485 connection using the following settings, found on the ‘Serial port settings’ page:


Also configure the TCP server settings:

5 connect the EW-11 to the HWS - use the github instructions: “The cables are Yellow = GND, Gray = B, Black = A.”

6 You will need to provide power to the EW-11. I can’t give you specific advice here as I am not an electrician, but something like a 5v power adapter wired into 240v would do the job, but of course don’t do this if you are not an electrician. There are open L/N/E spade terminals inside the HWS control box.

7 mount the EW-11 somewhere to give the antenna plenty of clearance, and button the unit back up

8 continue on with the HA configuration as per Github - you will need to enter the correct TCP Server IP and port details in your Modbus.yaml. You will know it is working correctly if the web portal Status page reports sent/received frames.

9 all done. your HWS is now controllable by HA, with all relevant temps reporting as sensors.

Extra info:
Seems like quite a handy little device - there are options for MQTT and other broadcasting modes in the server settings tab.

EW-11 User Manual
EW-11 application guide