IM710 15
Units with Modulating Heat
The VAV Box Output should be used to switch the VAV
boxes between heating and cooling control. While the unit is
in Startup, Recirc, or any heating operating state (UnocHtg,
MWU, or Heating), the VAV Box Output is in the Off (or
heat) position (field installed pilot relay de-energized)
switching the VAV boxes into heating operation.
VAV units have a “post heat” control feature which forces
the discharge air volume to a minimum before closing the
VAV Box Output when the unit leaves Recirc or any other
heating operating state. “Post heat” operation prevents
excessive duct static pressure that could otherwise occur
when the zone thermostats regain VAV box control.
1
When the unit is not in Startup, Recirc, or any other heating
operating state, the VAV Box Output is in the On (or cool)
position (field supplied pilot relay energized) switching the
boxes to cooling control.
Pump Start Output
The Pump Start Output (CCB1-BO3) supplies 24VAC to ter-
minal 113 on field terminal block (TB2) when the output is
on. To use this signal, the coil of the field supplied and
installed 24 VAC pilot relay must be wired across terminals
113 and 117 on TB2. When this output is on, 24 VAC is sup-
plied from the T3 control transformer through output relay
CCB1-BO3 to energize the field relay. Refer to the as-built
wiring diagram or to Figure 19 on page 39. The Pump Start
Output is On when water flow is required. It is Off at all
other states.
Field Analog Input Signals
Zone Temperature Sensor Packages
Table 5 lists the two zone (space) temperature sensor pack-
ages that are available for use with vertical self-contained
units equipped with a MicroTech II controller. A zone tem-
perature sensor (ZNT1) is optional for all vertical self-con-
tained units except for the 100% outdoor air CAV-ZTC
(SCC) unit in which case one is required. On all programs,
however, a zone temperature sensor is required to take
advantage of any of the following standard controller
features:
Unoccupied heating and cooling
Discharge air reset based on space temperature (DAC only)
Timed tenant override
Zone Sensor without Remote Setpoint Adjustment
The standard MicroTech II room temperature sensor package
that does not include setpoint adjustment can be used with
any vertical self-contained MicroTech II control configura-
tion. It includes a tenant override button.
This zone sensor must be field installed and field wired to
the unit using a twisted pair, shielded cable (Belden 8761 or
equivalent). Figure 7 on page 16 shows the required wiring
termination points.
Zone Sensor with Remote Setpoint Adjustment
The standard MicroTech II room temperature sensor package
equipped with a setpoint adjustment potentiometer is avail-
able to be used with CAV-ZTC (SCC) units. This sensor
package also includes a tenant override button. If wall
mounted setpoint adjustment is not required, the sensor
package without remote setpoint adjustment can be used on a
CAV-ZTC (SCC).
This zone sensor package must be field installed and field
wired to the unit using twisted, shielded cable. Four conduc-
tors with a shield wire are required. Cable with 22 AWG
conductors ( Belden 8761 or equivalent) is sufficient. Figure
6 shows the required wiring termination points.
.
Table 5: MicroTech II Zone Temperature Sensors
Mcquay
Part No.
Tenant
Override
Switch
Remote
Setpoint
Adjustment
For Use With
DAC
CAV-
ZTC
(SCC)
111048101 Yes No X X
111048102 Yes Yes X
CAUTION
Do not install this cable in the same conduit as
AC power wiring. Induced current and RFI from
AC wiring can interfere with the controls.
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