Economizer - Carrier 50PG20-28 Controls, Start-Up, Operation, Service And Troubleshooting Instructions

---_ECMN o r
Configuration---_AIR.Q_OVR.P to provide
economizer cooling.
IA.CF = 3 (Control Minilnmn Position) When IA.CF =
3, an external 4 to 20 mA somce is used to set the minilnum
position. The 4 mA signal corresponds to 0% and the 20 mA
signal corresponds to 100%. In this mode, confignrations such
as Configutvttion---_AIR.Q---_EC.MN and Configuration---_
AIR. Q---_AQ.MN are not used.
If the indoor fian is not operating, the economizer position
will be zero. The damper position may exceed the economizer
minilnum position to provide economizer cooling.
IAQ (Switch Input) Indoor air quality can also be lneasured
using a switch input. For the purpose of speci_ing the type of
switch input, low CO2 levels are considered normal. ]?he IAQ
switch input is defined by the configuration by Configuration
---_AIR.Q---_ILCF IAQ Level (Switch Input). Enthalpy and
IAQ are controlled by the saane switch input and therefore they
calmot be used simultaneously.
Configuration---_AIR.()---_IL(T = 0 (No IAQ) ThelLCF
= 0 confignration 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---_IL CF = 1 (DCV NO) or IL CF = 2
The Demand Control Ventilation (DCV) allows
the economizer minimum position to be decreased when there
is no IAQ probleln. If IAQ is lo,a; the economizer minilnmn
position is Minilnum IAQ Dmnper Position ((bnfigumtion
_AIIL Q--+AQ.M?€). If IAQ is high, the economizer minilnmn
position is the Economizer Minilnmn Position ((bnfiguration
-->AIR.Q-->ECM?€).
Configuration---_AIR.Q---_IL(T = 3 (Override NO) or
IL (T = 4 (Override NC) The damper override function
permits absolute positioning of the economizer damper for
ventilation purposes. The ovenide is active when IAQ is
high and inactive when IAQ is low. The override position
is configurable by the configuration by (bnfigumtion
_AIR.Q_OVR.P (Economizer Override Position).
OUTDOOR AIR QUALITY (Analog Input) The
ComJbrtLink 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 enteI_lg new values for (bnfiguration---_AIR.Q
_0. 4M and (bn figuration--+AIR. Q _0.2(131.
Con[iguration---_AIR.Q_OA.(T = 0 (No OAQ) This
signifies there is no outdoor air sensor installed. The delhult
value of OAQ is 400 ppm.
Con[iguration---_AIR.Q_OA.(T = 1 (DCV) The outdoor
air quality sensor analog input is for the value of OAQ.
Con[iguration---_AIR.Q_OA.(T = 2 (OAQ Lockout)
The outdoor air quality sensor analog input is only used to lock
out the outdoor ventilation. The economizer colrnnanded posi-
tion is set to 0% when the ppm exceeds the OAQ lockout value
configured tbr Configumtion---_AIR.Q_OAQ.L. The dethult
value of OAQ.L is 600 ppm.
FAN ENABLE (Analog IAQ Sensor) The DCV algoritban
will operate whenever the building is occupied and the indoor fan
is operating or whenever the IAQ algoritban has caused the
indoor fro1 to operate. The configuration Configuration
---_AIR.Q---_IA.FN (Fan Enable tbr IAQ), determines whether or
not the IAQ algorithm can turn on the indoor tSal.ff the indoor I'm1
is not operating, the economizer position wilt be zero. The dmnper
position may exceed Configumtion---_AIR.Q---_ECMN to pro-
vide eccmomizer cc×_ling.
Con[iguration---_AIR. Q---_IA.FN = O (Never) When lA.FN
= 0, the IAQ algoritban can never turn on the fmL
Configumtion---_AIR.Q---_IA.FN= 1 (Occupied) When
IA.FN= 1, the IAQ algorithln will turn on the indoor fan
whenever the building is occupied and IAQ/OAQ differential
is geater than the configuration Configumtion---_AIR.Q---_
DEON (Fan On AQ Differential). The indoor fma wilt rum off
when the IAQ/OAQ differential is less than the configuration
Configuration --+AIR. Q--+DEOF (Fan Off AQ Differential).
ECONOMIZER
MINIMUM
DAMPER
POSITION
(EC.MN)
MINIMUM
IAQ
DAMPER
POSITION
(AO.MN)
lOO
AQ
DIFFERENTIAL
LOW (AQD.L)
700
/
AQ
DIFFERENTIAL
HIGH (AQD.H)
Fig. 11 -- IAQ Control
INSIDE/OUTSIDE CO 2 DIFFERENTIAL
50