Basic Documentation

Functions
Fan control
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This function allows users to use the thermostat in universal applications such as
chilled/heated ceilings and radiator, etc. (see Chilled/heated ceiling and radiator
applications [➙ 36]).
In automatic mode, a dwelling time of 2 minutes (factory setting) is active. The fan
maintains each speed for at least 2 minutes before it changes to the next speed.
The minimum on-time can be adjusted from 1…6 minutes via parameter P59.
In automatic fan mode and with the room temperature in the dead zone, the control
valve is normally closed and the fan is disabled. With the fan kick function, the fan
can be released periodically at low speed for a minimum on-time (see above) even
if the valve is closed.
This function is used to avoid damage from moisture due to a lack of air circulation,
or to allow the return air temperature sensor to acquire the correct room
temperature.
➀
Periodic fan kick
➁
Minimum on-time
The periodic fan kick time can be selected individually for Comfort via parameter
P60, and for Economy via parameter P61.
● Fan kick value 0 (OFF) means the fan does not run in the dead zone.
● Comfort:
– Fan kick value 1...89 means the fan turns on at low speed every “x = 1...89”
minutes and the duration is equal to the fan minimum on-time.
– Fan kick value 90 means the fan runs continuously in the dead zone.
● Economy:
– Fan kick value 1...359 means the fan turns on at low speed every
“x = 1...359” minutes and the duration is equal to the fan minimum on-time.
– Fan kick value 360 means the fan runs continuously in the dead zone.
When the fan starts from a standstill, it starts at high speed for 1 second to ensure
safe fan motor startup by overcoming inertia and friction (selected via parameter
P67).
When the electric heater is switched off, the fan overruns for 60 seconds
(parameter P54) to avoid overtemperature of the electric heater or prevent the
thermal cutout from responding.
WARNING
Fan failure
In the event of fan failure, the thermostat cannot protect the electric heater
against over-temperature. Thus, the electric heater must feature a separate safety
device (thermal cutout).
Fan overrun for electric
heater
(RDF660MB only)
Fan minimum on- time
Fan operation in dead
zone (fan kick)
Notes
Fan start