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.
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.
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/
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.
Hi Ben
I managed to do the things I wanted such as using the Midea_ac_lan integration and the heat exchanger monitoring. Once I managed to get HACS installed the Midea was ok. It seemed to find the hardwired controller ok.
I don’t get too obsessed but the Midea ASHP is working better with a much smaller secondary pump. However, the installer will probably need to change the pipes over to make the plate heat exchanger operate on a counter flow basis. We need to wait for the weather to get colder! The installer was impressed by the temperature monitoring across the primary and secondary flows.
I live off Solar mostly with the occasional top up of the battery via my Flux tariff. The SolarEdge app has improved to give more control and I decide whether to not export from 4-7pm. So for two months I have been paid £100/month net.
Thanks very much Phil… that’s v. interesting. It sounds like you have a very similar install to me (i wonder if Igloo are familiar??). I will persevere with the HACS integration and see where that gets me.
Would you be able to share the modbus interface details please? I.e the registers, baud rate, id etc.? I have an 8kw unit and would like to monitor and log some data as well.
Thank you very much!
I haven’t implemented the Modbus interface as I found that temperature monitors across the plate heat exchanger was enough.
Now we have had a freeze I need to talk to the installer about changing the pipe work to counter flow for the heat exchanger.
The only thing the wired Midea controller gives is the heat output of the ASHP. I pretty sure that in the cold weather it doesn’t cope as efficiently as it might - COP of 2.5 typically when outside below 0c. I can differentiate defrost from cycling with the graphs.
@Filipe thank you for the reply!
I was searching around now and found a manual with the registers:
What was suggested was to connect directly to this Midea indoor controller as it supports modbus. Only a rs485 to usb adapter is needed and software to read the registers.
I have the new R290 Clivet unit and keen to get it onto modbus with HA, i did do this with the Grant unit i had. But there seems little info around about Midiea/Clivet heat pumps.
