Carrier 50FCQ 04-07 Series Service And Maintenance Instructions page 41

CONTROL POINT
CONTROL
APPROX. °F (°C)
CURVE
AT 50% RH
A 73 (23)
B 70 (21)
C 67 (19)
D 63 (17)
(18)
60
(16)
A
55
(13)
B
50
C
(10)
45 D
(7)
40
(4)
35
(2)
35 40 45 50 55 60
(2) (4) (7) (10) (13) (16)
APPROXIMATE DRY BULB TEMPERATURE °F (°C)
Fig. 67 — Enthalpy Changeover Set Points
Indoor Air Quality (IAQ) Sensor Input
The IAQ input can be used for demand controlled ventilation con-
trol based on the level of CO
duct.
Mount the accessory IAQ sensor according to manufacturer speci-
fications. The IAQ sensor should be wired to the AQ and AQ1 ter-
minals of the controller. Adjust the DCV potentiometers to corre-
spond to the DCV voltage output of the indoor air quality sensor at
the user-determined set point. See Fig. 68.
If a separate field-supplied transformer is used to power the IAQ
sensor, the sensor must not be grounded or the EconoMi$er
control board will be damaged.
When using demand controlled ventilation, the minimum damper
position represents the minimum ventilation position for VOC
(volatile organic compounds) ventilation requirements. The
maximum demand ventilation position is used for fully occupied
ventilation.
When demand controlled ventilation is not being used, the mini-
mum position potentiometer should be used to set the occupied
ventilation position. The maximum demand ventilation position
should be turned fully clockwise.
CO Sensor Max Range Setting
6000
5000
4000
3000
2000
1000
0
2 3 4
Damper Voltage for Maximum Ventilation Rate
Fig. 68 — CO Sensor Maximum Range Settings
2
85 90 95 100 105 110
(29) (32) (35) (38) (41) (43)
80
(27)
75
(24)
70
(21)
65
A
B
C
D
65 70 75 80 85 90 95 100 105 110
(18) (21) (24) (27) (29) (32) (35) (38) (41) (43)
measured in the space or return air
2
800 ppm
900 ppm
1000 ppm
1100 ppm
5 6 7 8
Exhaust Set Point Adjustment
The exhaust set point will determine when the exhaust fan runs
based on damper position (if accessory power exhaust is in-
stalled). The set point is modified with the Exhaust Fan set point
(EXH SET) potentiometer. See Fig. 66. The set point represents
the damper position above which the exhaust fans will be turned
on. When there is a call for exhaust, the EconoMi$er IV controller
provides a 45 ± 15 second delay before exhaust fan activation to
allow the dampers to open. This delay allows the damper to reach
the appropriate position to avoid unnecessary fan overload.
Minimum Position Control
There is a minimum damper position potentiometer on the
EconoMi$er IV controller. See Fig. 66. The minimum damper po-
sition maintains the minimum airflow into the building during the
occupied period.
When using demand controlled ventilation, the minimum damper
position represents the minimum ventilation position for Volatile
Organic Compound (VOC) ventilation requirements. The maxi-
mum demand ventilation position is used for fully occupied venti-
lation.
When demand controlled ventilation is not being used, the mini-
mum position potentiometer should be used to set the occupied
HIGH LIMIT
CURVE
ventilation position. The maximum demand ventilation position
should be turned fully clockwise.
Adjust the minimum position potentiometer to allow the mini-
mum amount of outdoor air, as required by local codes, to enter
the building. Make minimum position adjustments with at least
10°F temperature difference between the outdoor and return-air
temperatures.
To determine the minimum position setting, perform the following
procedure:
1. Calculate the appropriate mixed air temperature using the
following formula:
(T
T = Outdoor-Air Temperature
O
IV
®
OA = Percent of Outdoor Air
T = Return-Air Temperature
R
RA = Percent of Return Air
T = Mixed-Air Temperature
M
As an example, if local codes require 10% outdoor air during
occupied conditions, outdoor-air temperature is 60°F, and
return-air temperature is 75°F.
(60 x 0.10) + (75 x 0.90) = 73.5°F
2. Disconnect the supply air sensor from terminals T and T1.
3. Ensure that the factory-installed jumper is in place across
terminals P and P1. If remote damper positioning is being
used, make sure that the terminals are wired according to
Fig. 60 and that the minimum position potentiometer is
turned fully clockwise.
4. Connect 24 vac across terminals TR and TR1.
5. Carefully adjust the minimum position potentiometer until
the measured mixed air temperature matches the calcu-
lated value.
6. Reconnect the supply air sensor to terminals T and T1.
Remote control of the EconoMi$er IV damper is desirable when
requiring additional temporary ventilation. If a field-supplied re-
mote potentiometer (Honeywell P/N: S963B1128) is wired to the
EconoMi$er IV controller, the minimum position of the damper
can be controlled from a remote location.
To control the minimum damper position remotely, remove the
factory-installed jumper on the P and P1 terminals on the
EconoMi$er IV controller. Wire the field-supplied potentiometer
to the P and P1 terminals on the EconoMi$er
Fig. 66.)
41
OA RA
) + (T ) = T
x
x
O
100 R 100
M
® IV controller. (See