after having verified (several times) that all the machines making up the WE's air conditioning systems were actually functioning correctly, and taking advantage of Maria and Irene's shift, I climbed onto the platform to check the HVAC probe..WEB_HOT_TE because it was the only one the whole environment to disagree with the readings of others
To check its functionality I pressed it for a couple of seconds and from the real-time data display that Irene and Maria were following, we saw that it started reading the value that agreed with the other probes again.
as a reaction, the valve that regulates the post-heating coil immediately went from 25% to 0% and the room temperature slowly began to drop, as it does now at the time of writing.
I continue to monitor the situation
We intervened on site and, after some checks and tests, at 15:20 UTC we had to replace the temperature sensor (including its connector) of the post-heating control loop.
We preliminarily verified that the cold control loop was working well (signals in the first line of the attached plot), and that the problem was in the post-heating probe (channel HVAC_WEB_HOT_TE). In fact, from the comparison with a witness probe outside the loop and placed next to the probe in loop (INF_WEB_HALL_TE), it can be seen that between the 2 probes there was a discrepancy, which caused an excess correction of the post heating loop (HVAC_WEB_HOT_CORR), and this caused an increase of temperature.
From fig2, it can be seen that after replacement the new probe is in agreement with the witness probe, and therefore the temperature in the hall is returning to the set point value, equal to 22.5C.
