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Connecting Home Assistant to a Midea Heat Pump

 
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Air Source Heat Pumps (ASHPs)
Last Post by cathodeRay 2 years ago
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cathodeRay
 cathodeRay
(@cathoderay)
Illustrious Member Moderator
Joined: 4 years ago
Posts: 2357
Topic starter 04/10/2023 10:07 am  

@leichat - very useful. It looks like it has a direct modbus connection. From 3:17 in the video:

image

Modbus RTU / RS485 connections are two wire (and usually earth) and are usually marked A+ / B-, I think the visible A and B (and the mention of a third party controller) are near enough to mean this LG heat pump does have an accessible direct modbus connection, meaning this particular LG heat pump, and possibly other LG heat pumps, can be added to the list of heat pumps that can be monitored, and possibly controlled, over modbus. I didn't watch the whole video, but I get the impression he used modbus over TCP rather than RTU but that's a minor point, the major one is it has an accessible modbus connection. 

 


Midea 14kW (for now...) ASHP heating both building and DHW


   
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 Mosibi
(@mosibi)
Eminent Member Member
Joined: 2 years ago
Posts: 13
10/10/2023 4:37 pm  

My midea (clone) config for an esphome board can be found here, https://github.com/Mosibi/Midea-heat-pump-ESPHome if anyone is interested 



   
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cathodeRay
 cathodeRay
(@cathoderay)
Illustrious Member Moderator
Joined: 4 years ago
Posts: 2357
Topic starter 13/10/2023 7:04 am  

Just for the record, here is a comparison of the two ways I have tried to connect to a Midea heat pump, firstly all in Home Assistant using the midea_ac_lan add on to make the connection, which sniffs and/or queries the LAN/wifi data Midea sends to their servers, and secondly over a wired modbus connection and saved to a csv file, which, for display convenience here, I have pulled into HA using a file sensor (HA mumbo jumbo for a file reader). The former shows the ambient outdoor air temp as measured by the heat pump, the second the indoor air temp as measured by the MD02 temp sensor I added recently, which, apart from here being displayed in HA, has nothing to do with HA.

image

 

Two things I note: (1) the midea_ac_lan/HA record is flaky (not sure why, perhaps the wifi is flaky), the modbus connection is rock solid and (2) a comparison of the outdoor vs indoor temp shows my building appears to have considerable thermal mass (seen here as 'thermal inertia' - the indoor air temp stays pretty steady even as the outside air temp varies). This may or may not be useful when it comes to comparing continuous vs intermittent heat pump running, which I plan to do once the heating is back on (still currently off as it is mild, and as you can see the indoor air temp is still within an acceptable range).      


Midea 14kW (for now...) ASHP heating both building and DHW


   
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