You can use fan coil unit heating/cooling sequences for floor heating or cooling by
disabling the fan via P350.
The following functions allow the control of external equipment connected to the
Q1, Q2 and Q3 relay outputs:
Switching off external equipment when the thermostat is in
Protection mode
Switching on external equipment during…
● heating/cooling demand
● heating demand
● cooling demand
Energizing the contact when…
● the heating sequence is active
● the cooling sequence is active
Humidity control:
● Output to control dehumidifier
● Output to control humidifier
● When P351 = 1 and 2, these functions are not available.
● When fan is DC 0...10 V fan (P351 = 3) or fan is disabled (P350 = 0) and
related relays are not occupied by output (configure 1 stage or 2 stage as
On/Off on RDG26..KN), these functions are available.
● Do not use these functions in combination with On/Off valve control
(P201/P203 = 2 / 4 or P204/P205 = 4) to ensure temperature control accuracy.
If these functions are required, the total maximum current on the relay outputs
(Q1+Q2+Q3) must not exceed 2 A.
The relay output function can be enabled and tested as follows:
Relay output function
on …
Enable function via
Expert level parameter
Test function via
diagnostic parameter
The external equipment (e.g., fan coil unit) can be switched off via relay output to
save energy when the thermostat is in Protection mode and no temperature control
is requested.
Set the related output parameter to 1 to enable the function.
Relay contact is open when the thermostat is in Protection mode.
NOTICE! The relay contact does not switch on when the room temperature is
below the frost protection setpoint.
For application examples, see Relay functions [➙ 170].
During heating or cooling demand, the relay contact can be energized to control
external equipment, e.g., to run the pump for a water system (fan coil unit) or a
compressor.
To reduce wear and tear on HVAC equipment, the minimum output On/Off time of
the Qx relay output can be adjusted (1…20 minutes) via P212 and P213. The
factory setting is 1 minute.
Qx relay switching
function (P400, P401,
P402)
Switching off external
equipment in Protection
mode
Energizing the contact
during heating/cooling
demand
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