Carrier WeatherMaster 48HC04 Service And Maintenance Instructions page 52

To determine the minimum position setting, perform the following
procedure:
1. Calculate the appropriate mixed air temperature using the
following formula:
OA
(T ) + (T
x
O
100
T = Outdoor-Air Temperature
O
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 oc-
cupied 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. 71 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 IV controller. (See
Fig. 76.)
DAMPER MOVEMENT
Damper movement from full open to full closed (or vice versa)
takes 2 1 / minutes.
2
THERMOSTATS
The EconoMi$er IV control works with conventional thermostats
that have a Y1 (cool stage 1), Y2 (cool stage 2), W1 (heat stage 1),
W2 (heat stage 2), and G (fan). The EconoMi$er IV control does
not support space temperature sensors. Connections are made at
the thermostat terminal connection board located in the main con-
trol box.
OCCUPANCY CONTROL
The factory default configuration for the EconoMi$er IV control
is occupied mode. Occupied status is provided by the black jump-
er from terminal TR to terminal N. When unoccupied mode is de-
sired, install a field-supplied timeclock function in place of the
jumper between TR and N. When the timeclock contacts are
closed, the EconoMi$er IV control will be in occupied mode.
When the timeclock contacts are open (removing the 24-v signal
from terminal N), the EconoMi$er IV will be in unoccupied
mode.
DEMAND CONTROLLED VENTILATION (DCV)
When using the EconoMi$er IV for demand controlled ventila-
tion, there are some equipment selection criteria which should be
considered. When selecting the heat capacity and cool capacity of
the equipment, the maximum ventilation rate must be evaluated
RA
) = T
x
M
100
R
for design conditions. The maximum damper position must be cal-
culated to provide the desired fresh air.
Typically the maximum ventilation rate will be about 5 to 10%
more than the typical cfm required per person, using normal out-
side air design criteria.
A proportional anticipatory strategy should be taken with the fol-
lowing conditions: a zone with a large area, varied occupancy, and
equipment that cannot exceed the required ventilation rate at de-
sign conditions. Exceeding the required ventilation rate means the
equipment can condition air at a maximum ventilation rate that is
greater than the required ventilation rate for maximum occupancy.
A proportional-anticipatory strategy will cause the fresh air sup-
plied to increase as the room CO
CO set point has not been reached. By the time the CO
2
reaches the set point, the damper will be at maximum ventilation
and should maintain the set point.
In order to have the CO
2
this manner, first determine the damper voltage output for mini-
mum or base ventilation. Base ventilation is the ventilation re-
quired to remove contaminants during unoccupied periods. The
following equation may be used to determine the percent of out-
side air entering the building for a given damper position. For best
results, there should be at least a 10 degree difference in outside
and return-air temperatures.
OA
(T
x
O
100
T = Outdoor-Air Temperature
O
OA = Percent of Outdoor Air
T = Return-Air Temperature
R
RA = Percent of Return Air
T = Mixed-Air Temperature
M
Once base ventilation has been determined, set the minimum
damper position potentiometer to the correct position.
The same equation can be used to determine the occupied or max-
imum ventilation rate to the building. For example, an output of
3.6 volts to the actuator provides a base ventilation rate of 5% and
an output of 6.7 volts provides the maximum ventilation rate of
20% (or base plus 15 cfm per person). Use Fig. 77 to determine
the maximum setting of the CO
1100 ppm set point relates to a 15 cfm per person design. Use the
1100 ppm curve on Fig. 77 to find the point when the CO
output will be 6.7 volts. Line up the point on the graph with the
left side of the chart to determine that the range configuration for
the CO sensor should be 1800 ppm. The EconoMi$er IV control-
2
ler will output the 6.7 volts from the CO
when the CO concentration in the space is at 1100 ppm. The
2
DCV set point may be left at 2 volts since the CO
will be ignored by the EconoMi$er IV controller until it rises
above the 3.6 volt setting of the minimum position potentiometer.
Once the fully occupied damper position has been determined, set
the maximum damper demand control ventilation potentiometer
to this position. Do not set to the maximum position as this can re-
sult in over-ventilation to the space and potential high humidity
levels.
CO SENSOR CONFIGURATION
2
The CO sensor has preset standard voltage settings that can be se-
2
lected anytime after the sensor is powered up.
Use setting 1 or 2 for Carrier equipment.
1. Press Clear and Mode buttons. Hold at least 5 seconds
until the sensor enters the Edit mode.
2. Press Mode twice. The STDSET Menu will appear.
3. Use the Up/Down button to select the preset number.
4. Press Enter to lock in the selection.
5. Press Mode to exit and resume normal operation.
52
level increases even though the
2
sensor control the economizer damper in
RA
) + (T ) = T
x
M
R 100
sensor. For example, an
2
sensor to the actuator
2
sensor voltage
2
level
2
sensor
2