Carrier WeatherMaster 50HC04 Service And Maintenance Instructions page 39

to the P and P1 terminals on the EconoMi$er IV controller. (See
Fig. 74.)
DAMPER MOVEMENT
Damper movement from full open to full closed (or vice versa)
takes 2 1 / minutes.
2
THERMOSTATS
The EconoMi$er IV control works with conventional thermo-
stats that have a Y1 (cool stage 1), Y2 (cool stage 2), W1 (heat
stage 1), W2 (heat stage 2), and G (fan). The EconoMi$er IV
control does not support space temperature sensors. Connec-
tions are made at the thermostat terminal connection board lo-
cated in the main control box.
OCCUPANCY CONTROL
The factory default configuration for the EconoMi$er IV con-
trol is occupied mode. Occupied status is provided by the black
jumper from terminal TR to terminal N. When unoccupied
mode is desired, install a field-supplied timeclock function in
place of the jumper between TR and N. When the timeclock
contacts are closed, the EconoMi$er IV control will be in occu-
pied mode. When the timeclock contacts are open (removing
the 24-v signal from terminal N), the EconoMi$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 ca-
pacity of the equipment, the maximum ventilation rate must be
evaluated for design conditions. The maximum damper posi-
tion must be calculated 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
outside air design criteria.
A proportional anticipatory strategy should be taken with the
following conditions: a zone with a large area, varied occupan-
cy, and equipment that cannot exceed the required ventilation
rate at design conditions. Exceeding the required ventilation
rate means the equipment can condition air at a maximum ven-
tilation rate that is greater than the required ventilation rate for
maximum occupancy. A proportional-anticipatory strategy will
cause the fresh air supplied to increase as the room CO
increases even though the CO
By the time the CO level reaches the set point, the damper will
2
be at maximum ventilation and should maintain the set point.
In order to have the CO sensor control the economizer damper
2
in this manner, first determine the damper voltage output for
minimum or base ventilation. Base ventilation is the ventila-
tion required to remove contaminants during unoccupied peri-
ods. The following equation may be used to determine the per-
cent of outside air entering the building for a given damper po-
sition. For best results, there should be at least a 10°F
difference in outside and return-air temperatures.
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
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
2
set point has not been reached.
2
RA
) = T
x
M
R 100
20% (or base plus 15 cfm per person). Use Fig. 75 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. 75 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$er IV controller until it rises
above the 3.6 volt setting of the minimum position potentiometer.
Once the fully occupied damper position has been determined,
set the maximum damper demand control ventilation potenti-
ometer to this position. Do not set to the maximum position as
this can result in over-ventilation to the space and potential
high humidity levels.
CO SENSOR CONFIGURATION
2
The CO sensor has preset standard voltage settings that can be
2
selected anytime after the sensor is powered up. See Table 10.
Use setting 1 or 2 for Carrier equipment. See Table 10.
1. Press Clear and Mode buttons. Hold at least 5 seconds
until the sensor enters the Edit mode.
2. Press Mode twice. The STDSET Menu will appear.
Table 10 — EconoMi$er IV Sensor Usage
APPLICATION
Outdoor Air Dry Bulb None. The outdoor air dry bulb sensor is fac-
Differential Dry Bulb
Single Enthalpy
Differential Enthalpy
CO for DCV Control
2
using a Wall-Mounted
CO Sensor
2
CO for DCV Control
2
using a Duct-
Mounted CO Sensor
2
* CRENTDIF004A00 and CRTEMPSN002A00 accessories are used on
many different base units. As such, these kits may contain parts that will
level
not be needed for installation.
† 33ZCSENCO2 is an accessory CO
** 33ZCASPCO2 is an accessory aspirator box required for duct-
mounted applications.
†† CRCBDIOX005A00 is an accessory that contains both 33ZCSEN-
CO2 and 33ZCASPCO2 accessories.
3. Use the Up/Down button to select the preset number. See
Table 10.
4. Press Enter to lock in the selection.
5. Press Mode to exit and resume normal operation.
The custom settings of the CO
after the sensor is energized. Follow the steps below to change
the non-standard settings:
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 toggle to the NONSTD menu
and press Enter.
4. Use the Up/Down button to toggle through each of the
nine variables, starting with Altitude, until the desired set-
ting is reached.
5. Press Mode to move through the variables.
6. Press Enter to lock in the selection, then press Mode to
continue to the next variable.
39
sensor. For example, an
2
sensor to the actuator
2
sensor voltage
2
ECONOMI$ER IV WITH OUTDOOR AIR
DRY BULB SENSOR
Accessories Required
tory installed.
CRTEMPSN002A00*
HH57AC078
HH57AC078 and CRENTDIF004A00*
33ZCSENCO2
33ZCSENCO2† and 33ZCASPCO2**
OR
CRCBDIOX005A00††
sensor.
2
sensor can be changed anytime
2
sensor
2