Monitoring a Midea 12kW Monoblock

Hardware
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I have a Midea 12kW Monoblock installed May last year. I have run mine without weather compensation over the winter peaking at 42C flow temperature in the very cold weather (-9C) but mostly at 38C and recently at 35C.

Being fearful of a whopping energy bill and having wood to burn we just used it for the upstairs of 1990 300m2 chalet home with 22 new large low temperature radiators over three zones. Heat Loss 12kW with 50% down to air leakage and the eaves the poorest insulated. No need to reroof for years. At the end of January 6.3kW Solar with 20kWhs of battery storage added. Very happy with £120/month electric bill on GO including modest EV charging.

The ASHP works much better heating everything but not 24/7 although we do run during the off peak period.

I must admit that at -9C in December it was cold upstairs (17-18C) after a few hours. It ran until 10pm. We persisted at 38C flow until the last few days when it sank to -9C. The net result has been we only used 2176 kWhs up to a few days ago for heating, which I can’t complain about.

I feel the Midea cycles a bit on low output (below 7kW output capacity). Maybe 30 minute on then 15-25 minutes off. I am also suspicious of the plate heat exchange because my magnetic thermometer reads about 5-6C lower than the target flow temperature. This obviously limits the output of the radiators.

So I am thinking of a level 2 monitoring system with DS18B20 sensors to emonTx4 possibly via the breakout block. I have the Modbus wired controller for connecting to Midea Cloud and believe that the Operating Parameters section provides all the useful monitoring and diagnostic data when combined with flow and return temperature sensors on the heat exchanger ports (claimed to be 12-16kW but not clear what temperatures) and CT clamp data. I have an Emporia Energy Monitor for 16 circuits.

I’d welcome hearing from anyone about using the Industrial RS485 to USB to read the Midea Operating Parameters or more generally about writing code to create a Midea Modbus interface. It’s a few years since I last used Borland Delphi, but very familiar with object oriented programming languages.

Thank you to everyone from this newbie thinking of a first step into home energy monitoring. Not keen on Home Assistant.

Phil

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Welcome, I moved this to a new thread - usually better as it is a new conversation.

2 Likes
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It’s been quite intense trying to understand everything that is involved over the last few days. The reading of the Midea should be possible over MODBUS with a RS485 to USB device. I don’t mind the extra expense of the Waveshare Industrial one. I assume it is similar to configure to the one in
https://community.openenergymonitor.org/t/installing-emoncms-onto-a-pc-or-mac-and-using-with-multiple-modbus-meters-e-g-sdm230/19849

I am uncertain about whether to go for a Raspberry Pi as I prefer reliable storage and an SD card seems a weak link. I don’t fancy doing it all 4 times. I bought a 4 year old Lenovo ThinkCentre usff Window 10 Pro PC which only uses 8W for £140. It has i5, 8GB Memory and 256 SSD. That one is for Astrophotography and is mounted on an EdgeHD! I have installed Home Assistant using Oracle VirtualMachine on a slower older i3. Not keen on HA.

@glyn.hudson tells me I need emonTx4 for the 4-6 DS18B20 temperature sensors. I’m not sure whether these can be connected to a Windows PC.

The electric meter can be an extra device on MODBUS. I have the details of the Midea MODBUS interface. There must be 130 registers, but only a few are of interest such as the output power, primary flow rate, flow and return temperatures, DHW tank temperature, outdoor temperature, compressor frequency, status bits.

I have also wondered how easy it is to read data from my Emporia Energy Monitor using their cloud API. I have CT clamps on 16 circuits including the ASHP and solar inverter (bidirectional as I have batteries).

This newbie will be very grateful for guidance on the kit to go for.

Phil

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You could look at something like

Do they have an API? The following discussion indicates that they do not, but people are trying to reverse engineer one. I haven’t read it all though, so maybe there is one or somebody has succeeded.
https://community.emporiaenergy.com/topic/api-to-pull-data/

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Hello

Thanks for your suggestion. Yes, I am looking at adding temperature sensors using a Wemos 8266 D1 board.

I now have a Raspberry Pi 3B running Home Assistant since yesterday, and have Access to my SolarEdge kit, some Gove Thermometers and a few other services. I will try the Midea_AC_Lan integration before focusing on the temperature sensors via ESPHome.

At the moment just trying to familiarise myself with HA. I note there is an integration for emonCMS, but still to look at it.

Phil