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General Information
Chapter Overview
This chapter contains information about the following:
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Unit Control Module 4.2 (UCM 4.2)
The UCM 4.2 is a microprocessor-based, Direct Digital Controller (DDC) for the (Variable Air
Volume) VAV terminal unit. It contains the control logic to modulate the flow of supply air through
the VAV terminal in response to the load requirements within the VAV zone.
The function of the UCM is to control the VAV terminal unit to vary the volumetric airflow rate to
the zone. Units have been made with either pneumatic, analog electronic, or microprocessor
controls (DDC VAV). This manual discusses only terminal units with Comm4 DDC/VAV controls.
Factory installed DDC/VAV controls are available with all single duct terminal units, dual duct units,
as well as parallel fan-powered and series fan-powered units. Two UCMs are required for dual duct
units (one for the heating duct and one for the cooling duct).
The UCM modulates a VAV's damper blade based on a zone temperature, measured airflow, and
airflow set points to continuously control conditioned air delivery to the space. The volume of
incoming air is monitored and the damper adjusts to provide accurate control independent of the
duct pressure. The damper modulates between operator airflow set points depending on space
conditions. Additionally, fan and heat outputs may be energized depending on the application.
Available inputs include a twisted/shielded communication link, zone sensor, auxiliary temperature
sensor (optional), CO
power.
Specifications
Power Requirements
The UCM 4.2 requires 24 VAC, 50/60 Hz, and up to 50 VA, depending on the number of heat outputs
(stages), which consume 10 VA each. Our factory installed devices draw from 3 to 12 VA. The
outputs are rated at 12 VA max.
Operating Environments - UCM 4.2
32° to 140°F (0° to 60°C), 10% to 90% relative humidity, non-condensing
Storage Environments - UCM 4.2
-40° to 150°F (-40° to 65.6°C), 10% to 90% relative humidity, non-condensing
Mounting
Typically, the UCM 4.2 is factory installed. However, UCM 4.2 is available with retrofit kits, in which
case it must be field installed.
Tracer Summit and UCM 4.2 Communications Link Wiring
Communications Link wiring must be 18 AWG twisted shielded pair wire. Each conductor must be
stranded tinned copper. The maximum total wire length is 5,000 feet (1,524 m). Refer to
Installation and Wiring, " p. 12
6
Unit Control Module 4.2 (UCM 4.2)
Specifications
UCM 4.2 Enhancements
UCM 4.2 Features
Shipping
Storage
Sensor (optional), and Occupy/Unoccupy Sensor (optional), and 24 VAC
2
for further information about wire selection.
"UCM 4.2
VAV-SVX01C-EN
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