Carrier WEATHERMASTER 50HJQ004-016 Product Data page 171

Deciding which curve is used is a function of the outdoor
climate and the type of economizer utilized. Since
EconoMi$er IV is a fully integrated economizer, the range
where outdoor air can be utilized for free cooling is
expanded and the A and B curves may be used. The con-
trol point table in the EconoMi$er IV Changeover diagram
below provides assistance for whether the A and B curves
will be suitable. In general terms, a hot and humid climate
may be a reason not to use the A curve, while a cooler cli-
mate might be more applicable for using the A or B curve.
The EconoMi$er IV has expanded outdoor air capability.
For a changeover economizer which cannot utilize simulta-
neous economizer and compression, both A and B curves
APPLICATION
Outdoor Air Dry Bulb
Differential Dry Bulb
Single Enthalpy
Differential Enthalpy
CO for DCV Control using a
2
Wall-Mounted CO
CO for DCV Control using a
2
Duct-Mounted CO
*CRENTDIF004A00 and CRTEMPSN002A00 accessories are used
on many different base units. As such, these kits may contain parts
that will not be needed for installation.
†33ZCSENCO2 is an accessory CO
→
ECONOMIZER SENSOR USAGE CHART
Sensor
2
Sensor
2
sensor.
2
would potentially be undesirable since the temperature and
humidity levels are too high without compression assis-
tance to provide effective cooling. Therefore, most
changeover economizers utilize the D curve.
Differential enthalpy — The EconoMi$er IV will be enabled
based on the comparison of the enthalpy of the return air
and outside air. When the outside air enthalpy is lower than
he return side, the unit will be in economizer mode.
Using the EconoMi$er IV controller for implementing
different control changeover strategies requires the use of
different combinations of dry bulb and humidity sensors as
outlined in the EconoMi$er IV Sensor Usage table.
ECONOMI$ER IV WITH OUTDOOR AIR
DRY BULB SENSOR
Accessories Required
None. The outdoor air dry bulb sensor is factory installed.
CRTEMPSN002A00*
CRENTDIF004A00*
33ZCSENCO2
33ZCSENCO2†
and
33ZCASPCO2**
** 33ZCASPCO2 is an accessory aspirator box required for duct-
mounted applications.
††CRCBDIOX005A00
33ZCSENCO2 and 33ZCASPCO2 accessories.
905
HH57AC078
HH57AC078
and
CRCBDIOX005A00††
is an accessory that contains both
171