IAQ control with On/Off damper: P453 = 2 or 3
If On/Off damper control is selected, the following parameters are available:
● P453: Indoor air quality damper (2 = On/Off (normally open), 3 = On/Off
(normally closed))
● P456: IAQ fan P-band Xp
● P357, P353: Fan min. output
● P359 & P360, P355: Fan max. output
The following graphics show the IAQ control by running the fan, in applications with
On/Off damper.
The damper is fully open if CO
2
(IAQ) concentration is higher than the setpoint
(P023).
The hysteresis of the damper is fixed at 100 ppm. The 3-speed fan switch off point
is 100 ppm below the switch on point.
In the dead zone (no H/C demand), the damper does not open, and fan does not
operate until CO
2
concentration reaches the IAQ setpoint.
On/Off damper can be connected directly to thermostat terminal Q3 or Y4 (see IAQ
- CO2 connection diagrams [➙ 167]) or controlled via S-Mode object 103: On/Off
damper demand.
Notes:
● When On/Off damper is selected, the fan speed depends on the higher fan
request between temperature demand and IAQ demand.
● For energizing the damper during IAQ demand, select “IAQ damper” P453 = 3
(normally close).
This logic can be inverted by selecting P453 = 2 (normally open).
Enable IAQ frost protection to protect the coils (set P109 frost setpoint) when fresh
air from outside is supplied to the equipment.
Frost protection closes the damper if the outside temperature value from the bus
(sent to RDG via e.g. LTE-mode, zone 31) is below the setpoint and open again if.
the outside temperature increases by 2K (hysteresis) above the setpoint.
Frost protection is not supported if the fan is disabled (P350 = 0) or the application
is set to 4-pipe with 6-port valve (H/C no fan). (RDG200KN, RDG260KN,
RDG200T, RDG260T)
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