Hello,
The Daikin integration uses the air conditioner’s internal sensors.
But using the internal sensors (temp, humidity) doesn’t make sense, the temperature is distorted, it is not the room temperature and you should be able to use external sensors as you do with IR integration… Or with climate thermostats.
I find it hard to understand that this is not foreseen but after spending hours searching I have found nothing…
The Daikin units themselves use the built in sensors (the ones displayed in the integration) to work out when they have reached their target temperature and humidity values. I agree they are quite skewed given that most models have those sensors only centimetres away from the unit’s exhaust vent.
I personally use sensors elsewhere around my rooms for judging what the temperature really is, but it is useful to know what the Daikin thinks it is. That way I know that setting it to cool to 20 in summer gets the area around my desk to 22-23, which is plenty comfortable, for example.
The integration just lets us tell the Daikin what mode and temperature/humidity targets to have, but doesn’t actually control when the Daikin is blowing or not, so having the integration allow you to specify a different temperature sensor display for the room value in place of the Daikin’s sensor will not actually change it’s behaviour.
A solution to have the Daikin acting more accurately is to find out of your model supports having an external temperature sensor wired into it, and having a tradie come and install it at least a meter away from the unit and away from the direct airflow of the unit. Obviously not free or DIY, but would absolutely solve the accuracy issue.
I definitely don’t recommend doing it yourself as air conditioners like these are directly wired to the mains power and to expose the circuit board in just about all of them (at least as far as split-system models go) also exposes the power supply and you have to run the wiring right next to it, so the chances of hurting yourself are pretty high. The capacitors on these things can store more than enough power to hurt a person for quite some time after being disconnected from power. The tradie who installed my wireless module, a very similar procedure, got me to switch off the breaker for my unit the day before and leave it off, and he was still pretty cautious around it as he went.
I don’t have a external temp sensor installed to mine, but I believe the Daikin unit starts reporting it’s value back through the API in the place of the internal temperature sensor, but YMMV, that’s just what I have extrapolated from poking around the API endpoints.
Hello and thank you for taking the time to make these clarifications.
Indeed the best solution would be to deport this sensor. I will not do it because my air conditioner is new and I would lose the warranty.
It would be good however that the integration allows the use of an external sensor and I find it regrettable not to have this facility.
My air conditioner also goes up consumption values that I find erroneous. I don’t have any more information, I just created a utility_meter to accumulate the value.
My ducted system seems to be reporting the temperature of the duct in the roof space rather than the room sensor (BRP15B61).
Hello,
What is regrettable before anything is that Daikin is apparently publishing nothing about their API and their S21 serial port specifications / protocols.
My Daikin indoor units’ indoor temperature measurement is utterly broken, especially in heating mode. As soon as the thing turns on, the measured indoor temp. raises very fast, quickly leading to the unit to stop blowing because it “thinks” the target temperature is reached. But this is wrong, all wrong as the room temperature is still way behind the set target. A few minutes later, sometimes just one minute after, the unit turns back on… to stop again pretty soon.
@FreelancerJ already explained the reasons. It’s easy to demonstrate by the way: just after the unit stops blowing, switch to “fan” mode and the indoor temp. measurement drops by many degrees in just a few dozens of seconds.
So, a very bad temp sensor placement and an inability to add a remote/external temperature sensor unless, maybe, via a wired remote control. For that reason I bought a BRC073A1 a while ago but still am missing the S21 cable to connect it… in place of the Wi-Fi module because yes, the S21 port is used by that module already 
I want to figure out if the temperature sensor integrated in the wired RC can be used by my indoor unit models (FTXM and CTXM) as a replacement to its internal one. A menu entry exists on the wired RC for that purpose but it might be restricted to some indoor unit models.
IF that sensor can be used, it means the indoor temperature can be fed to the indoor units via the S21 port, which would open a way to integrate the indoor units with any indoor temperature measurement mechanism.
I think that would be the only proper way to proceed. Turning off/on/off the AC units from HASS according to the indoor temperature measurements (others than the AC units’) is wrong in my opinion.