Snap a photo of labels on the box outside and look it up (most of the time you will see the consumption right on the label). Unless they changed it very recently, the unit will always be power-bound, that is it will always operate at the nominal power level, whether you have 1 or 5 zones active (1 zone will simply cool faster). As with any aircon it’s not about how much it consumes but how fast your house leaks the cold/heat out.
Compatibility wise it works with any variant of LR7 and BM24 panels, if you have NEO or NEXUS panels the chances are the protocol is different.
I’ve tried to get this working to no prevail. I have the actron control unit, but I don’t have a “KEY” line, rather:
SENS-1
SENS-2
AUX
COMMON
POWER
When I press a key, measuring AUX and COMMON I see no voltage change (~3v) even whilst holding key. As soon as I press the power key the HVAC turns on, with zero voltage change.
Possibly I have a different kind of unit is all I can assume. I even tried disconnecting AUX and the commands from display still worked on just using COMMON and POWER.
As I was using multimeter I was switching settings and as soon as switched to BATT (i.e. 1.5v/9v) the AC turned off.
Looks like you must have a different model wall controller to the ones that we have that must use some different form of communication between the wall panel and the outside unit.
I am not sure that you would be able to get the setup working like we have with your current wall controller. Out of curiosity what model is your wall unit ?
It seems the model doesn’t support multiple displays, so that’s why there’s no “KEY” like.
It does have a relay (home automation) mode though.
Adding resistance between AUX/COMMON turns it on; removing it turns it off. I’ve connected this to GPIO with a BC549 transistor, making it a smart switch.
I found 16-bit pulses (not 40-bit) and have decoded them—I’ll share the code soon.
These pulses seem to come from the display to the controller, meaning the controller itself doesn’t handle logic, rather the display takes all inputs (from user and temp sensors) then decides whether to run or not. But further testing is tricky as I don’t have an oscillator.
Have done some more testing to see if I can work out the communication protocol from Display → Controller:
Tested Display powered by external 19V pack, the display did not send any pulses.
Tested plugging ESP into the controller (without display plugged in), no pulses.
Tested a 4.7k resistor on power/common lines with ESP plugged in to see if the controller needs to see enough resistance, no pulses.
Sent the same a well known “run” state via TX (without display plugged in) and controller did nothing.
If buttons were pressed (i.e Power On/Off, Zone 1 On/Off) whilst on 19V adapter, these would be applied as soon as controller plugged in (display has a battery for flash memory). But this shows the 16-bit pulse state is not persisted to controller via button presses, but rather comes from the display.
It seems pulses are only sent when the display is plugged in to the controller. There doesn’t seem to be any polling or boot up pulses either.
I don’t have enough expertise to figure out why the pulses only happen when display and controller are together. Have ordered a logic analyser as my final hope.
OK had another look and this unit appears to be 22 years old - obviously if it aint broke dont fix it ruled with these people !! On the label it is identified as
There appears to be very little information online about the main AC unit - whilst there is some info about the control panel not sure which family it falls into.
Success!! Managed to get the B512GZ controller to work. This was by far one of the biggest projects I’ve done.
As it turns out the B512GZ is a “smart” display, and a “dumb” controller. Where as most of the displays/discussion in this thread are “dumb” displays and a “smart” controller. The dumb display setup is ideal where you have multiple displays.
This display communicates by sending 16-bit pulses every 370ms. Frames are a 10us low and high of 1900us for short/5900us for long. The other displays here have a 40-bit sequence with temp data etc. This display literally just sends FAN Speed (Hi/Med/Low), Compressor (Stage 1/2), Heat (On/Off) and Zone (1/2 or both). Thus if I wanted to go HA I needed to work out all the logic for running the compressor and fans myself.
My main challenge was actually getting the buck to work (as this was to replace the display and I wanted no external wires). It seemed that as soon as the buck was connected to power/common no pulses were being seen (either by controller or by a logic analyser). I thought it was due to noise so added all sorts of caps and ferrite chokes. Even tried a linear reg with no luck. Also tried an opto with no luck.
Spent a good day or so trying different approaches to work that one out. Finally asked ChatGPT to do some deep research and one out of many suggestions was to use a 4-10Ω resistor just before the buck VIN (or in my case caps before the buck). It worked! It seemed this stopped the pulses (or the edges rather) from being absorbed by the big caps.
1000µF cap + 100µF cap + 1µF cap (after buck - i.e. 5v)
10kΩ Epoxy Dip NTC Thermistor + .1µF + 1µF in parallel and a 10k resistor from 3.3v. Using ESP32 (not common) GND as I was getting upstream noise when compressor was running. Using this as a backup temp sensor until I can test out Aqara wireless sensors.
BC549 transistor - base goes up to a 330Ω resistor and into TX pin (GPIO17)
Also have the voltage divider setup (which others have documented here) still setup for easy RX testing if I wish to plugin the display. Using 22k:4.7k, as I was reading 3.3v with 20k (too close for comfort).
ESPHome:
receives a 16-bit frame from home assistant.
sends the current frame every 370ms to the controller (GPIO17).
will send idle (i.e. system off) frames to controller if HA drops out (i.e. hasn’t sent latest frame in over 1 minute). This is to protect situation where HA drops off and compressor is left running in the wild.
sends it’s onboard temp sensor to HA
Home Assistant:
runs all the logic of when to run fans/compressor and to select stage 1/stage 2.
handles the hysteresis for temp control (i.e. 0-1°C off, >1°C stage 1, >1.5°C stage 2)
ensures compressor will not run for a period of time after turning off (i.e 180 seconds) to prevent short cycles
runs fan for a period of time after compressor is turned off (i.e. 30 seconds) to prevent condensation build up
will automatically ramp up fan speed if a high workload is perceived
uses outdoor and forecasted temp to work out cool/heat mode when in auto
Will share this code soon as I’m still tweaking a few things. Glad I got this one figured out!
What’s the model on the back of the display. How does it plug in etc?
Also 22 years is impressive! Our building is replacing all units after just 12 years due to the refrigerant in them being hard to source. And the new refrigerant is much more efficient. Is a new compressor on the cards?
