Titus Mixing Box Controls IOM - Manual (Page 12)

Mixing Box Control Installation Manual
IOM-MBC-00 08-30-04
12 of 15
Solid-State Enthalpy Sensor - C7400A
Use the Solid State Enthalpy Sensor – C7400A and Solid
State Logic Module W7459A with Modulating Damper
Motor - M7415 to proportion outdoor and return air
dampers in economizer systems.
C7400A solid-state element senses temperature and
humidity. Sensor mounts in any position up to 200 feet (61
meters) away from the W7459. Use one sensor in outdoor
air for single enthalpy control. Use two sensors, one in
return air and one in outdoor air, for differential enthalpy
control. W7459A attaches to the damper motor’s side for
proportional control of damper. Combines solid-state
enthalpy changeover control, minimum damper position
potentiometer and compressor staging relays. To select
air temperature and humidity suitable for free cooling, use
enthalpy set point on W7459.
Table 13 and 14 list application operational specifics,
respectively. Figure 17 depicts a solid-state enthalpy
sensor.
Table 13. Application Specifics
t n e m m o C n o it a c il p p A
Sensor Used With C7400A
For use with actuator M7415
Discharge Air Temperature Input Thermistor sensor
C7150B or C7046
Minimum Position Potentiometer
Adjustment
YES
Terminals for Remote Minimum
Damper Position
YES
Output Relays 2 spdt
Table 14. Operating Specifics
Specific Description
Case Duct-mounted
Temperature
Sensing Element:
Thermistor
Output Signal 4-20 mA current signal; increases
from 4 mA to 20 mA as enthalpy
decreases
Operating ambient
temperature
-40 to 125° Fahrenheit (-40 to
+52° Celsius)
Shipping
temperature rating:
-40 to 150° Fahrenheit (-40 to
+66° Celsius)
Maximum power
consumption
0.45 Vac
Maximum supply
voltage
18 to 24 Vdc
Electrical connection Two ¼-inch quick-connect
terminals
Listed by Underwriters Laboratories Inc.
Figure 17. Solid-State Enthalpy Sensor
Location and Mounting
Outdoor air sensing: The Enthalpy Sensor may be
mounted in any orientation where it is exposed to freely
circulating air, but protected from rain, snow, and direct
sunlight.
Return air sensing: For differential enthalpy control, a
second C7400A enthalpy sensor is connected to the
W7459. It is mounted in the return air duct. Contact Titus
if specifications call for differential enthalpy control.
Air Temperature Sensor – C7150B
Use the air temperature sensor – C7150B and the single-
zone system – W973 with the damper motor – M7415A to
sense mixed or discharge air in rooftop packaged air
conditioning equipment. See Figure 18.
Figure 18. Air Temperature Sensor