50
→
EC.MN
or
Configuration
→
AIR.Q
→
OVR.P
to provide
economizer cooling.
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 CO
2
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.
Configuration
→
AIR.Q
→
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.
Configuration
→
AIR.Q
→
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
).
Configuration
→
AIR.Q
→
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
Comfort
Link control is configured for outdoor air quality sen-
sors which provide 4 to 20 mA for 0 to 2000 ppm. If a sensor
has a different range, the ppm display range must be reconfig-
ured by entering new values for
Configuration
→
AIR.Q
→
O.4M
and
Configuration
→
AIR.Q
→
O.20M
.
Configuration
→
AIR.Q
→
OA.CF =
0
(No OAQ) — This
signifies there is no outdoor air sensor installed. The default
value of
OAQ
is 400 ppm.
Configuration
→
AIR.Q
→
OA.CF =
1
(DCV) — The outdoor
air quality sensor analog input is for the value of
OAQ
.
Configuration
→
AIR.Q
→
OA.CF =
2
(OAQ Lockout) —
The outdoor air quality sensor analog input is only used to lock
out the outdoor ventilation. The economizer commanded posi-
tion 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.
FAN ENABLE (Analog IAQ Sensor) — The DCV algorithm
will operate whenever the building is occupied and the indoor fan
is operating or whenever the IAQ algorithm has caused the
indoor fan to operate. The configuration
Configuration
→
AIR.Q
→
IA.FN
(Fan Enable for IAQ), determines whether or
not the IAQ algorithm can turn on the indoor fan. If the indoor fan
is not operating, the economizer position will be zero. The damper
position may exceed
Configuration
→
AIR.Q
→
EC.MN
to pro-
vide economizer cooling.
Configuration
→
AIR.Q
→
IA.FN =
0
(Never) — When
IA.FN
= 0
, the IAQ algorithm can never turn on the fan.
Configuration
→
AIR.Q
→
IA.FN
= 1
(Occupied) — When
IA.FN
= 1
, the IAQ algorithm will turn on the indoor fan
whenever the building is occupied and IAQ/OAQ differential
is greater than the configuration
Configuration
→
AIR.Q
→
DF.ON
(Fan On AQ Differential). The indoor fan will turn off
when the IAQ/OAQ differential is less than the configuration
Configuration
→
AIR.Q
→
DF.OF
(Fan Off AQ Differential).
100
700
INSIDE/OUTSIDE CO
2
DIFFERENTIAL
AQ
DIFFERENTIAL
LOW
(AQD.L)
AQ
DIFFERENTIAL
HIGH
(AQD.H)
MINIMUM
IAQ
DAMPER
POSITION
(AQ. MN)
ECONOMIZER
MINIMUM
DAMPER
POSITION
(EC. MN)
INCREASING VENTILA
TION
VENTILATION FOR PEOPLE
VENTILATION FOR SOURCES
Fig. 11 — IAQ Control
a48-8154
Summary of Contents for 48PG24
Page 68: ...68 Fig 14 Low Voltage Control Schematic 48PG20 28 Units without Humidi MiZer System a48 7627...
Page 69: ...69 Fig 15 Low Voltage Control Schematic 48PG20 28 Units with Humidi MiZer System a48 8227...
Page 70: ...70 Fig 16 Low Voltage Control Schematic 50PG20 28 Units without Humidi MiZer System a48 7778...
Page 71: ...71 Fig 17 Low Voltage Control Schematic 50PG20 28 Units with Humidi MiZer System a50 8101...
Page 72: ...72 Fig 18 Power Schematic Units without Humidi MiZer System a48 7628...
Page 73: ...73 Fig 19 Power Schematic Units with Humidi MiZer System a48 8228...
Page 74: ...74 Fig 20 Component Arrangement Units without Humidi MiZer System a48 8229...
Page 75: ...75 Fig 21 Component Arrangement Units with Humidi MiZer System a48 8230...
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