Titus Mixing Box Controls IOM - Manual (Page 5)

Mixing Box Control Installation Manual
IOM-MBC-00 08-30-04
5 of 15
Installation
The logic module mounts on the side of the three-position
damper motor (M8405A). When planning the installation,
allow enough clearance for maintenance and service.
Ensure the location is protected from rain and snow.
1. Align logic module to prongs of the Damper Motor.
2. Press logic module and Damper Motor together.
3. Secure logic module to damper motor using the
supplied mounting screw.
Settings and Adjustments
The minimum position potentiometer keeps the outdoor air
damper from closing completely during system operation
to provide ventilation. Figure 6 shows potentiometer
adjustment slots. Use a screwdriver to make adjustments.
1. Connect 24 Vac at terminals TR and X (D is not
connected).
2. Adjust thumbwheel on motor for desired minimum
position.
Wiring
Disconnect power supply before connecting wiring to
prevent electrical shock or equipment. All wiring must
comply with applicable local codes, ordinances, and
regulations. See Figure 7 for wiring diagram depicting the
three-position control system.
Solid-State Enthalpy Sensor - C7400A
The solid-state enthalpy sensor – the C7400A has a solid-
state element that senses temperature and humidity. It
combines solid-state enthalpy changeover control,
minimum damper position potentiometer and compressor
staging relays.
The solid-state enthalpy sensor – C7400A when used with
the Solid State Economizer Logic Module – W7459 and
three-position damper motor – M8405 helps to position
outdoor and return air dampers in economizer systems.
Figure 8 depicts the solid-state enthalpy sensor.
Use for enthalpy control as follows:
•
One sensor in outdoor air for single enthalpy control.
• Two sensors, one in return air and one in outdoor air,
for differential enthalpy control. Contact a Titus
representative, if specifications call for differential
enthalpy control.
The enthalpy set point of the logic module selects the air
temperature and humidity suitable for free cooling.
Operational Ratings
Table 6 highlights operational ratings.
Figure 6. Enthalpy Set Point Potentiometer (Three-
Position System)
Figure 7. Three-position Control System Circuit