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Chapter Overview
This chapter contains information
about the following:
— UCM 4.0 Power Wiring
— Zone Sensor Wiring
— Communication Wiring
— DIP switch Settingsire Selection
VAV-SVX01B-EN
UCM 4.0 Installation
and Wiring
UCM 4.0 Power Wiring
Power Requirements
Caution: Disconnect all power external
to the unit to prevent injury or death
from electrical shock. Use copper
conductors only. The use of aluminum
or other types of wire may result in
overheating and equipment damage.
Use at least 16 AWG for power wiring
and connect to terminal TB1-1 (+) and
TB1-2 (-). 24 VAC is required to power
the UCM control and has an acceptable
voltage tolerance of 20 to 28 VAC.
Replace the UCM control box cover
after field wiring to prevent any
electromagnetic interference.
NOTE: A dedicated 24 VAC, 50VA NEC
class 2 transformer is recommended to
power the UCM. When powering
multiple UCM's from one transformer,
polarity must be maintained. Terminal
TB1-1 is designated positive (+) and
terminal TB1-2 is negative (-) to the unit
casing ground. All wiring must comply
with the National Electric Code (NEC)
and local codes. Maximum wire lengths
should be based on NEC specifications.
The power consumption for cooling
only Series F Models (VariTrac and
VariTrane) is 12 VA (4 VA for the air
valve/actuator and 8 VA for the board).
Units with fans and/or reheat outputs
are rated at 10 VA maximum for
magnetic contactors and 12 VA
maximum for mercury contactors for
each output. To determine the total UCM
power requirement, add the power
consumption per stage to the circuit
board power requirement. For example,
a Series F unit containing magnetic
contactors with three stages of reheat
would consume 42 VA.
NOTE: VariTrane and VariTrac cooling only
Series D and E models consume 20 VA
(12 VA for the actuator and 8 VA for the
board). The heating output ratings
remain the same.
Refer to Figure 1 for UCM terminal
locations.
Zone Sensor Wiring
Location and Mounting
A zone sensor in each control zone
should be located in the most critical
area of the zone. Sensors should not be
mounted in direct sunlight or in the
area's supply air stream. Subdivision of
the zone may be necessary for ad-
equate control and comfort.
Avoid mounting zone sensors in areas
subject to the following:
— Drafts or "dead spots" behind doors or
corners.
— Hot or cold air ducts.
— Radiant heat from the sun or
appliances.
— Concealed pipes or chimneys.
— Unheated or uncooled surfaces behind
the sensor such as outside walls.
— Air flows from adjacent zones or other
units.
Wiring
Each unit must be controlled by a zone
sensor that is designated specifically
for use with the UCM control. Field
wiring for the zone sensors must meet
the following requirements:
— Must be 14 to 18 AWG.
— Refer to the sensor instructions for
terminal connections.
— If local codes require enclosed
conductors, the zone sensor wires
should be installed in conduit. Do not
route zone sensor wires in conduit with
24 VAC or other high power conducting
wires.
Multiple UCM's Per Zone Sensor
Up to three (3) UCM's may be con-
nected to a single zone sensor and
thumbwheel set point.
— Connect terminal connections TB3-1,
TB3-2, and TB3-3 in parallel (i.e. daisy
chain) from the master UCM to the
slaved UCM(s). NOTE: Proper polarity
must be maintained.
— Cut jumper wires W1 and W2 on the
slaved UCM's (never cut jumper wires
W1 and W2 on the master UCM).
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