The damper position depends on CO
2
value. If CO
2
(IAQ) concentration is higher
than the setpoint (P023), damper is open.
In dead zone (no H/C demand), damper does not open, and fan does not run until
CO
2
concentration reaches IAQ setpoint + ½ of the P-band.
DC damper can be connected directly to the terminal U1 of thermostat or controlled
via S-Mode object 102: DC damper demand.
IAQ control with On/Off damper: P453 = 2 or 3
If On/Off damper control is selected, the following parameters can be used:
• 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.
If CO
2
(IAQ) concentration is higher than the setpoint (P023), damper is fully open.
The hysteresis of the damper is fix to 100 ppm. The 3-speed fan switch off point is
100 ppm below the switch on point.
In dead zone (no H/C demand), damper does not open, and fan does not run until
CO
2
concentration reaches IAQ setpoint.
On/Off damper can be connected directly to the terminal Q3 or Y4 of thermostat
(see IAQ - CO2 connection diagrams [➙ 159]) or controlled via S-Mode object 103:
On/Off damper demand.
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