Control over My Airconditioning/Heatpump

It started with our Mitsubishi heatpump. Someone on the internet had found a way to control it via Home Assistant. Sadly, this heatpump broke down in April... In July (yes, 10 weeks later!) we got a new one. A Panasonic this time.

A side-note, I recently started working at the New Zealand Meteorological Service (MetService)... So the title is a double joke...

Controlling a heatpump

Our new heatpump, aside from having the capacity to heat up our lounge, which is nice during winter (did I mention we were out of proper heating for 10 weeks already? If not, well, it was cold!), is a Panasonic. And lo and behold, one of my favourite maker groups has a way to build a Home Assistant supporting integration.

Without a NZ$200 wifi module, but with about NZ$25 of parts from Ali Express and a PCB print you can get for free (I'll upload it here as well later), you can have your Home Assistant integration done!

It is, from looking at the PCB, pretty obvious where everything should go.

To put everything together, you'll need a pretty fine-tipped soldering iron. And I also suggest to have a steady hand, and if possible, a "third hand" with a magnifying glass.

DO NOT BREATH IN THE SOLDERING SMOKE, IT IS NOT HEALTHY FOR YOU!

The easiest order of soldering everything:

1. Solder the headers on your ESP32 board
   1. Tip: position the header pins in the PCB, then place the ESP32 on top. Don't solder them to the PCB (yet), but it helps getting them nice and cleanly poking through the holes.
2. Solder the 10k resistors in place. Do not solder anything in the 4k7 slot!
3. Solder the mosfets in place, the correct way round, with the middle pin sticking "out"
4. Solder the diode in place (note the orientation!)
5. Position the ESP32
   1. Now, attempt to connect a USB cable to the ESP32. You'll notice that it won't fit if you also solder the capacitor in place flush with the board
   2. Position the capacitor and ESP32 board loosely, so that you can still connect the cable.
   3. Take a photo of your positioning
6. Solder the capacitor in its place, according to the photo you just took
7. Solder the ESP32 in place, or solder a row of header-connectors in place so you can plug it in and pull it out easily (In case of the latter, ignore the positioning malarky above)
8. WASH YOUR BOARD!
9. Seriously, make sure there are no remnants of flux etc. on the board. Flux is not funny stuff.

Yay! Your chip board is done! It's time to give it a quick run through, before the final step of soldering.

You can use either the ESPHome web interface, or a self-hosted interface.

Create your YAML for ESPHome. Here's mine:

yaml:

1. substitutions:

2.   devicename: esp32-airco-01

3.   long_devicename: Panasonic Climate Lounge

4.   pcb_version: "P11-PTH-C3 250214"

6. esphome:

7.   name: "${devicename}"

8.   name_add_mac_suffix: false

9.   comment: "${long_devicename} ${pcb_version}"

10. esp32:

11.   board: esp32-c3-devkitm-1

12.   framework:

13.     type: esp-idf

14.   variant: ESP32C3

15. external_components:

16.   source: "github://DomiStyle/esphome-panasonic-ac"

17.   components:

18.     - panasonic_ac

19. wifi:

20.   ssid: !secret esphome_wifi_ssid

21.   password: !secret esphome_wifi_password

22.   ap:

23.     ssid: "${devicename} Hotspot"

24.     password: !secret esphome_ap_password

26. captive_portal:

28. web_server:

29.   port: 80

31. logger:

32.   level: DEBUG

33. # Enable Home Assistant API

34. api:

35.   encryption:

36.     key: "your_encryption_key_here"

37. ota:

38.   - platform: esphome

39.     password: !secret ota_password

40. bluetooth_proxy:

41. uart:

42.   tx_pin: GPIO21

43.   rx_pin: GPIO20

44.   id: ac_uart

45.   baud_rate: 9600

46.   parity: EVEN

47. switch:

48.   - platform: restart

49.     name: "$long_devicename Restart"

51. climate:

52.   - platform: panasonic_ac

53.     id: lounge

54.     type: cnt

55.     name: "$long_devicename"

56.     vertical_swing_select:

57.       name: "$long_devicename Vertical Swing Mode"

58.     outside_temperature:

59.       name: "$long_devicename Outside Temperature"

60.     current_power_consumption:

61.       id: power_consumption_lounge

62.       name: "$long_devicename Power Consumption"

63.       unit_of_measurement: W

64.       accuracy_decimals: 0

65.       device_class: power

66.       state_class: measurement

67. sensor:

68.   - platform: total_daily_energy

69.     name: "$long_devicename Total Daily Energy"

70.     power_id: power_consumption_lounge

71.     filters:

72.         - multiply: 0.001

73.     unit_of_measurement: kWh

74.     device_class: energy

75. time:

76.   - platform: homeassistant

77.     timezone: "Pacific/Auckland"

78.     id: my_time

My procedure of loading an ESP32 is via building through a self-hosted web version of ESPHome, downloading the factory binary file, and uploading it via the CLI

bash:

1. esptool write_flash 0 esp32-airco-01.factory.bin

I prefer using the CLI over the web interface, as the web interface has been quite flaky for me from time to time.

Once the flashing of the ESP32 is done, give it a test-run. Connect it to power, and see if you can get the logs via the web interface, and if you can find it in Home Assistant. Give it at least a few minutes to power up.

Finally, solder the wiring to connect the whole chip to the heatpump. I prefer to do this last, because when the wires are connected, the chip has a bit of a wobbly stand, so it is easier to do the pre-connection tests without the wires.

To connect the wires, grab your PAP cable. Put the clip facing downward, and the not-wires-sticking-out part of the clip facing you.

The cables to solder on to the JP1 points 1, 2, 3, and 5 are from left to right

Wire up as follows:

In the photo above, you can see it a bit. Note that the clip is facing upward in my photo, due to the twisting of the cables. For the colours in the photo, the order is:
Black - Red - White - Orange - Dark Orange
The Orange (second to last) is snipped short.

DISCONNECT AND FULLY POWER OFF YOUR HEATPUMP/AC

Plugging in this construction is pretty straight forward. Open the front flap of your heatpump. You'll notice on the right side a manual Start/Stop button (that's your emergency control button), and a cover that is held in place by a Philips Head screw at the bottom right of the cover.

Unscrew the cover, and you should see the connector in which you can plug your device. Be careful plugging it in, the pins bend quite easily. Don't use any force!

Carefully position your board in the space next to the access point. Be careful, you'll probably see the mains power lines. Don't touch those, and ensure your board is well clear of them!

Close the cover, screw it back in place, close the front main cover, and you're done. Restore power to your heatpump and listen out for any issues.

If all goes to plan, the heatpump should power up, and with that, provide power to your device. After a few minutes, your device should start showing in ESPHome to read out the logs wirelessly, and in Home Assistant!

Congratulations! You're done!