Simple two-point-controller on top of Faikin

[klausj1]

Hi all,
I bought a Faikin because I had problems with the Daikin controller:

• I never was able to reach the target temperature. Measuring the temperature in the indoor unit is really not a good idea, and the Daikin cannot use an external thermometer - the Faikin can. I never was able to reach the target temperature, most of the time it was too hot
• When the target temperature is somehow reached, the heatpump starts to go on and off in very short cycles. This looks so (the blue curve is the power, measured externally), and for sure this is not good for the heatpump:

With the Faikin auto-mode, I also had troubles (see #256 , maybe I did not understand correctly how the Faikin works).

Therefore I implemented a simple two-point controller as home assistant automation, with these settings:

• Turn on "my" controller
• Set Heat mode or cool mode
• Set target Temperature for the room
• Parameterize Temperature offset (difference between target temperatur above and the target temperatur sent to the Faikin/Daikin)
• Parameterize Hysteresis

At least on my unit, I need a negative Temperature offset (otherwise I always get a too high temperature), which is not possible with the Faikin settings (as far as I understood - heatover cannot be set to negative values)

In addition, the temperatur offset is not used if the current temperature is too far away from the set value, so that target temperatur of the Faikin/Daikin is only reduced when the target temperatur is almost reached.

Even with these settings, I had the same problem as without the Faikin - the Daikin controller goes on and off in very short cycles near the target temperature. Therefore I now set the controller to off when the Daikin goes to a compressor rate of 0Hz. And I turn the controller on again, when the current temperature is below target Temperature minus hysteresis. (See figure below, I hope this is understandable with the figure)

With this, I was able to achieve:

• Using the inverter functionality, because the Daikin controller is still active
• Reaching the target temperature (inside the defined hysteresis), as I turn on and off the Daikin when its outside the range defined by the hysteresis
• Avoiding the very short on/off cycles
• Hopefully this is simple to configure (play with the Temperature offset and the Hysteresis), no need to play with somehow complex settings of a PID-controller as shown here.

For me this works perfectly:

(explanation: the target temperature (not shown in the graph, sorry) is 19.5 degrees. You can see that the Faikin target temperature is adjusted when the 10.5 degrees are almost reached (at ~07:28 and ~07:41). At ~07:46 I manipulated the Daikin target temperature manually to force the Daikin to turn off, so that I could test if setting the Daikin controller to off is working - you can see that the heating goes off). At ~08:02 the current temperatur is lower than the target temperature (19.5) - hysteresis (0.5), and heating is turned on again. At ~08:25 the current temperatur is higher than the target temperature (19.5) + hysteresis (0.5), and heating is turned off.)

The inverter functionality is used as well, the power ("Leistung", blue curve) goes down to little more than 100 watts:

If somebody is interested, I attach the home assistant automation (maybe I'll change that to a pyhton script later on).
HA_Faikin_Controller_Automation.txt (it is Yaml, but I cannot attach Yaml here).

To use this, you need to manually create helpers and set their values:

It would be great if the Faikin directly could offer such a functionality, so that there is no need for a separate Home assistant controller. There is not much missing ;)

[revk]

That's great work.

Not ruling it out. My main objective was right temperature control, and turning off/on was only real way to get that.

What may be an idea is a choice of temperature control algorithms. At present I do have a lot of settings that allow different ways of working anyway, but not quite what you have done.

[wurmtal868]

Disclaimer:
I disabled OTA beginning of February. If the behavior below has been changed in the mean time, please ignore this comment!

I guess there a discrepancy what users expect " Faikin Auto-BLE mode +/- 0.5K" to do and what it actually does.
Through observation I came to the conclusion that Faikin Auto-BLE uses a set point of the target temperature minus 0.5 K with a hysteresis of 0.1K for heating and a set point of target temp plus 0.5K for cooling. Here is a short screen capture of the GUI while heating.
The set temperature is constantly changing while BLE is around 20.6 °C.

Faikin_auto.mp4

Faikin Auto-BLE it switches the outdoor unit faster than it can follow.(No RPM while target = 30 °C)

The screenshot below shows the indoor set temperature versus BLE temp and power consumption of the outdoor unit

"Zieltemperatur" is the target captured using the Daikin Cloud integration, which even slower than the compressor in following the changes.
Sometimes the compressor is ready to start and sometimes it's not resulting in very short cycle.
The short cycles lead to a higher energy consumption while the room temperature stays at the low end of the desired window.
I recommend adjusting the set points for heating on/off.

[revk]

The underlying design was to maintain an exact temperature, not try and avoid short stop/starts. There are a load of settings to control this, and the latest code makes those settings much easier to access via the web interface. So you can fine tune it to do what you want in most cases.

Assuming the blue line is the temperature, it is doing really well maintaining that. If you set to ±2℃ it will reduce the level of on/off cycling.

But the ±½℃ does mean that, but it also has some prediction settings for the trend of temperature, and so can end up being tighter than that because it predicts it will go outside the range soon if it continues on or off. The set point is based on the temperature the BLE thinks it is and the temperature the aircon thinks it is so will have any needed offset on that as the basis. It then sets a lot higher or lower to turn on and off using settings to turn on and off (heatover/coolover, etc).

You can change the heatover/coolover, etc, settings to change how that all works. There is also a more conventional hysteresis thermostat control which can reduce the on/off cycles. Again in latest code.

Generally, obviously, I would recommend staying on latest code as it allows for changes and new settings and options.

[MUN0X]

If I understand your explanation correctly, you could have just enabled the thermostat function within faikin.
The functionality you ask for is already there and was discussed in the following topic

But I agree that offsets should be made signed values. A negative offset will dropthe power draw once the setpoint is reached.

[klausj1]

Is it possible to see the target temperature sent from the Faikin to the Daikin via MQTT? That would be interesting to have it in the home assistant and see historically which values are sent.

[klausj1]

And thanks a lot for the super-fast Beta version!

[revk]

I thought we did provide that in some
MQTT.

[MUN0X]

That info can indeed be found in mqtt. You need to define a custom mqtt-sensor in home assistant to extract it from the json and have it reported as a sensor.

[klausj1]

Thx, I managed to do this:

mqtt:
  sensor:
  - name: faikinaz_temp_sent_to_daikin
    state_topic: "state/faikinAz/status"
    unit_of_measurement: '°C'
    value_template: "{{ value_json.temp }}"

I will create some graphics and see what it does and if I understand it.

[klausj1]

Maybe i should illustrate this via an example to see if i have the logic correct? From what I can see in the code, Faiking calculates a setpoint for the Daikin unit via the following formula: set = max + reference - measured_temp + heatover With:
Set= value to be sent to daikin
max = autot+autor+switchtemp ==> essentially setpoint of faikin
reference = temperature measured by the daikin unit itself
measured_temp = temperature of BLE sensor if present, else daikin measured temperature
Heatover = offset to ensure heating by the daikin unit.

Ah, I just read this more detailed. I was not aware that the temperature measured by the Daikin (reference) is used at all for controlling if I have a BLE sensor. I would like to use only the value of the BLE sensor, is there any configuration with which I can achieve this? I saw termref, which is "Percentage inlet rather than home temp used by your aircon". With this I can set the weight of the inlet temperature (I assume this is the temp. of the liquid) vs the home temp measured by the Daikin, right?

OK, probably this is the same request as above from @MUN0X :

it would be nice if we could disable it via a boolean :-) eg.set = reference + (max - measured_temp)*boolean + heatover"

[revk]

Tempadjust does the same adjustment as before, to allow for Daikin and external temp being different.

I changed to order of things and created the separate setting flags to allow a lot more flexibility.

The logic for that bit is the same...

If you want the room heated, so want a set point higher than the measured temp, but the daikin thinks it is even hotter already, you have to tell the daikin an even higher temp. Otherwise the daikin will not realise you want it hotter. The daikin will heat based on reference as it does not know measured temp.

Other bits were wrong and I have made it separate steps now and more options.

[MUN0X]

I beg to differ, the setpoint calculation has fundamentally changed due to the most recent changes.
The case were the daikin measures a wrong/higher temperature is covered by temptrack.
With both tempadjust and temptrack enabled (= default settings) you get the following.

Original calculation:
set = max + reference - measured_temp + heatover
or set = (min + max) / 2.0 + reference - measured_temp + heatover for fair comparison

Initial beta:
set = (min + max) / 2.0 + (reference - measured_temp) +heatover

Current implementation in stable:
set = reference + (reference - measured_temp) + heatover

I argue that if (tempadjust) set += reference - measured_temp; should be changed to if (tempadjust) set += (min + max) / 2.0 - measured_temp;
With both tempadjust and temptrack enabled you then get the original behavior. temptrack enables the daikin following/tracking its own measurement. tempadjust provides a reasonable proportionality between the desired temperature and the current temperature.

[revk]

I changed temptrack as I was not happy with the name and used where it was. I did say. It should not be using reference as the basis by default. If it is, I need to change it. It was not intended to be.

[revk]

It should also never use reference as basis and adjust for reference.

So I'll check the code now.

[MUN0X]

Sorry, i think i missed the else if

[revk]

FYI this is typical of what I have now, I expect it will look the same even with the changes I have made.

[revk]

OK, this explanation will probably help others and be worth putting in the manual anyway. I have now added to Advanced.

Firstly, and thank you for finding this, I had temp.track set on by default, this is a mistake, I have issued code to correct this now. The default should be temp.track off, and temp.adjust on.

So what it will be now is one of three options for the basis for the set point, before applying heatover, heatback, etc.

1. temptrack off, and tempadjust on, now the default.

(min + max) / 2.0 + (reference - measured_temp)

This is basically the set point you asked for, adjusted for Daikin seeing wrong temp.

2. temptrack on, regardless of tempadjust

reference

This is a tracking set point so allows you to be telling the Daikin, for example, "2 degrees more than you think the temperature is now" so as to have it heat up but without too much power, by setting heatover to 2 for example.

3. temptrack off, and tempadjust off

(min + max) / 2.0

This is just using the actual set point as the basis without adjustment.

There should never be reference + (reference - measured_temp) as that would be silly.

[klausj1]

Thank a lot! I'll try this, probably when its time to cool, as probably no heating is necessary this season anymore.