Titus TA1 Installation, Operation And Maintenance Manual

Installation, Operation, and Maintenance Manual
General Information
Power Requirements
TITUS TA1/TA2 controllers operate on 24 VAC power. Power
required to operate the controller and actuator is 7 VA plus any ou tput
loads for fan relays, heating contactors, and control valves (assume
10 VA each). Always switch control voltage off prior to disconnecting
any wires from the controller to prevent possible damage to control
components.
Damper Control
TITUS TA1/TA2 controllers provide pressure independent VAV
control for terminal primary air valves. Primary airflow volume is
monitored by means of a multipoint center-averaging velocity sensor
located in the inlet duct. Differential pressure is measured by an on-
board platinum ceramic trans ducer. Dampers are always shipped full
open and move counter-clockwise (CCW ) to close. The primary
damper opens and closes to vary air volume to match cooling
demand. Changes in static pressure will result in damper position
changes for a given flow volume. In automatic changeover(ACO)
sequences, the primary damper also moves to match heating
demand. If the primary fan system is off and th e terminal is calibrated
to control a minimum flow limit other than 0 cfm, the damper will drive
full open. Flow limit adjustments are made using a digital DC
voltmeter at the thermostat (As shown in Figure 1).
Live Supply Volume Readout
A voltage output corresponding to actual primary air volume may be
monitored at the thermostat to assist in balancing and troubleshooting
these units. This output signal follows the same cfm vs DC voltage
calibration curve that is shown on Page 2. The same thermostat
calibration cable (TITUS P/N 100310-01) that is used to make airflow
limit adjustments is also used to read primary air volume on the
outermost meter taps. (As shown in Figure 2)
Supply Air Temperature Sensing
A duct-mounted thermistor is used t o m e a s u r e p r i m a r y a i r
temperature in sequences involving automatic changeover (ACO) or
morning warm-up (MW U). It is fastened to the inlet duct with a
sheetmetal screw and wired to terminals 'X' and 'Y' on the controller.
Alternatively, autochangeover and morning warm-up may be trigger ed
by a contact closure. When controller terminals 'X' and 'Y' are shorted
together, the unit will operate in the heating or morning warm-up
mode. When there is an op en circuit between 'X' and 'Y', the unit will
operate in the cooling mode.
Night Setback/Unoccupied Signal
Units ordered with optional night setback (NSB) sequences employ a
differential pressure switch (As shown in Figure 3) to sense loss of
primary duct static pressure. By this method, these units change
operating mode when the air handler fan is de-energized.
Alternatively, night setback operation may be triggered by a 24 VAC
signal (10 mA) from a source external to the unit. Whenever 24 VAC
is applied to controller terminals '-NS B' and 'NSB', unit will operate in
night setback mode.
Installation Manual
TA1/TA2 Controller
ANA-IOM-1.0
Figure 1.
MAX/AUX MIN
INCR INCR
HEATING
TITUS SYSTEMS
V
50 70
METER
TAPS
Cooling Supply Volume
Meter Taps
Figure 2.
Figure 3.
6-15-02
MIN
MAX
INCR
INCR
COOLING
90 V
METER
TAPS
Pressure Switch