ECONOMIZER MINIMUM DAMPER POSITION
(EC. MN)
MINIMUM
IAQ
DAMPER
POSITION
(AQ. MN)
VENTILATIONINCREASING | VENTILATION FOR PEOPLE |
|
VENTILATION FOR SOURCES
and PM
100 | 700 | INSIDE/OUTSIDE CO2 DIFFERENTIAL |
AQ | AQ |
|
DIFFERENTIAL |
| |
DIFFERENTIAL |
| |
LOW (AQD.L) |
| |
HIGH (AQD.H) |
| |
|
|
C07010
Fig. 20 − IAQ Control
48/50PG
IA.CF = 3 (Control Minimum Position)
When IA.CF = 3, an external 4 to 20 mA source is used to set the minimum position. The 4 mA signal corresponds to 0% and the 20 mA signal corresponds to 100%. In this mode, configurations such as Configuration→AIR.Q→EC.MN and Configuration→ AIR.Q→AQ.MN are not used.
If the indoor fan is not operating, the economizer position will be zero. The damper position may exceed the economizer minimum position to provide economizer cooling.
IAQ (Switch Input)
Indoor air quality can also be measured using a switch input. For the purpose of specifying the type of switch input, low CO2 levels are considered normal. The IAQ switch input is defined by the configuration by Configuration→AIR.Q→II.CF IAQ Level (Switch Input). Enthalpy and IAQ are controlled by the same switch input and therefore they cannot be used simultaneously.
II.CF = 0 (No IAQ)
The II.CF = 0 configuration signifies that there is no IAQ switch input. The damper will operate at the EC.MN position when the space is occupied and the indoor fan is on.
II.CF = 1 (DCV NO) or II.CF = 2 (DCV NC)
The Demand Control Ventilation (DCV) allows the economizer minimum position to be decreased when there is no IAQ problem. If IAQ is low, the economizer minimum position is Minimum IAQ Damper Position (Configuration→AIR.Q→AQ.MN). If IAQ is high, the economizer minimum position is the Economizer Minimum Position (Configuration→AIR.Q→EC.MN).
II.CF = 3 (Override NO) or II.CF = 4 (Override NC)
The damper override function permits absolute positioning of the economizer damper for ventilation purposes. The override is active when IAQ is high and inactive when IAQ is low. The override position is configurable by the configuration by Configuration →AIR.Q→OVR.P (Economizer Override Position).
Outdoor Air Quality (Analog Input)
The ComfortLinkt control is configured for outdoor air quality sensors which provide 4 to 20 mA for 0 to 2000 ppm. If a sensor has a different range, the ppm display range must be reconfigured by entering new values for Configuration→AIR.Q →O.4M and Configuration→AIR.Q→O.20M.
OA.CF = 0 (No OAQ)
This signifies there is no outdoor air sensor installed. The default value of OAQ is 400 ppm.
OA.CF = 1 (DCV)
The outdoor air quality sensor analog input is for the value of OAQ during demand control ventilation operation.
OA.CF = 2 (OAQ Lockout)
The outdoor air quality sensor analog input is only used to lock out the outdoor ventilation. The economizer commanded position is set to 0% when the ppm exceeds the OAQ lockout value configured for Configuration→AIR.Q→OAQ.L. The default value of OAQ.L is 600 ppm.
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