Titus Mixing Box Controls IOM - Manual (Page 13)

Mixing Box Control Installation Manual
IOM-MBC-00 08-30-04
13 of 15
The sensor consists of thermistor sensor element used in
ventilation duct systems. Negative temperature coefficient
(NTC) causes the resistance to decrease as the sampled air
temperature increases. This resistance change is used to
control the W973 and W7415A. Setting and calibration not
required.
Operation
Table 15 highlights operational ratings of the air temperature
sensor.
Enthalpy Changeover Set Point
With single enthalpy the enthalpy changeover set point is set to
return the outdoor air damper to minimum position when the
enthalpy rises above its set point. The enthalpy set point scale
markings, located on W7459, are A, B, C, and D in Figure 20.
Figure 20. Performance Characteristics for Enthalpy Changeover Settings A, B, C, and D
Table 15. Operation Ratings
Specification Performance
Maximum ambient
temperature
250º Fahrenheit (125º
Celsius)
Operating temperature
range
-30 to 150º Fahrenheit (-34 to
65º Celsius)
Resistance/ Temperature
(NTC)
300 ohms at 77º Fahrenheit
(25º Celsius)
Resistance sensitivity per
degree at midrange
70 ohms per degree
Fahrenheit
Electrical connections ¼-inch quick-connect
terminals