Titus Mixing Box Controls IOM - Manual (Page 4)

Mixing Box Control Installation Manual
IOM-MBC-00 08-30-04
4 of 15
Settings and Adjustments
1. Connect 24 Vac to motor at terminals T and X
(Terminal D is not connected).
2. Adjust thumbwheel on motor for desired minimum
position.
Operation
A single-pole, single-throw (SPST) low-voltage controller
is used to control the three-position Damper Motor.
•
Fully open – when controller provides 24 Vac to D
and T, motor is energized and drives fully open.
• Fully closed – when power is removed from
terminals T and D, and the motor spring returns to the
fully closed position.
• Mid-position – when controller provides 24 Vac to T
and X, motor is energized and drives to the adjustable
mid-position (minimum position).
An adjustable minimum position can be reached from
either the fully closed or fully open position. From fully
closed, the motor drives open to the minimum position;
from fully open the motor spring returns to the minimum
position.
Verification
Operate the motor through its complete open-close stroke.
If necessary, release one of the previously tightened
linkage connections to prevent damage. Check for proper
operation, ensuring the linkage does not bind and the
motor travels smoothly throughout its fully open and full
closed positions. This motor checkout ensures:
1. The motor operates the load.
2. The motor responds properly to the controller.
3. There is no binding of the linkage or motor stalling
at any point of travel.
If motor does not operate properly, check for proper
voltage or mechanical binding in linkage or damper.
If questions arise regarding this product, contact your
distributor or Titus representative.
Logic Module – W7459C
The logic module provides control for the damper motor.
Use the enthalpy set point of the logic module to select air
temperature and humidity suitable for free cooling. Figure
5 depicts the logic module.
Remote Minimum Position Control
Remote control of the outdoor air dampers can be used, if
temporary additional ventilation is required. The
potentiometer in the logic module – W7459 controls the
minimum position of the dampers.
Operation
Table 4 provides operational information.
Figure 5. Three-Position Logic Module
Table 4. Operational Ratings
Operation Rating
Operating ambient
temperature
25º Fahrenheit t
p
to +125º
Fahrenheit (32 to +52º Celsius)
Humidity 5 to 95 percent relative humidity
Input voltage
24 Vac, 50/60 hertz
Relay contact rating
at 24 Vac
1.5 A run, 3.5 A inrush
Application Use with three-position Damper
Motor - M8405A
Discharge air
temperature input
Single-pole, single-throw (spst)
Minimum position
potentiometer
adjustment
None
(Minimum position adjustment is
built into Damper Motor M8405)
Terminals for remote
minimum damper
position
None
Output relays 2 single-pole, dual-throw (spdt)