In the heating sequence, when the return water temperature exceeds 30 °C
(factory setting, P366), fan operation is enabled even if the fan start delay time
(P365) is not reached.
The universal input "coil temperature" (P150, P153 or P155 = 12) is required to
activate this function.
When the electric heater (2-pipe/4-pipe) is switched off, the fan overruns for 60
seconds (P352) to avoid overtemperature of the electric heater or prevent the
thermal cutout from responding.
A minimal DC fan speed 2 is available on electrical heater applications with DC fan
control.
For other applications, the fan overrun can be enabled by setting the expected
running time to a max. value of 600 sec (P352) for drying the heating/cooling
exchangers and reducing the risk of moisture after the system stops. The default
value is 0. The fan is set to the minimal fan speed during fan overrun.
Fan failure
In case of fan failure, the thermostat cannot protect the electric heater against
overtemperature. For this reason, the electric heater must have a separate safety
device (thermal cutout).
The "Clean fan filter reminder" function counts the fan operating hours and displays
message "FIL " to remind users to change/clean the fan filter as soon as the
threshold is reached. This does not impact thermostat, which continues to run
normally. The function is set via P501 (default = Off (0)).
The "Clean filter reminder" is reset when the operating mode is manually set to
Protection and back.
In Auto mode, the default fan mode is automatic. The fan mode can be changed to
Manual by pressing the FAN button. The fan returns to automatic mode after each
switchover from Comfort to Economy, and vice versa.
To allow the heating/cooling coil to reach its temperature, fan start can be delayed
by a time period set via P365.
Function for On/Off control outputs is listed as per the following figure:
Fan control is set to enable by default (P350 = 1), if the thermostat is set with
control sequence "H/C ceiling with PICV and 6-port ball valve as changeover". For
this application, where the combi valve PICV controls the flow rate and the 6-port
ball valve works as changeover heating / cooling, fan control can:
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