Mammoth 800 to 5500 CFM: Dedicated Outdoor Air System with Enthalpy Wheels (VHC) - Manual (Page 8)

MAMM-VHC-IOM-1A (JANUARY 2013) 8
Power Supply
Units are available in all voltages and phases. Please see
Appendix E for electrical data. These units may or may not
have a factory installed disconnect switch. If disconnect is
field supplied, provide a disconnect as per local electrical
codes and NEC. Use copper conductors only.
All field wiring must comply with NEC and local require-
ments. In Canada, electrical connections must be in accor-
dance with CSA C22.1 Canadian Electrical Code Part One.
Units equipped with electric preheaters and/or post heaters
have either single-point or two-point power connections.
See Appendix E , submittal data and/or nameplate to de-
termine which. All units equipped with two-point electric
heaters require two-point power connection—one to the
unit control panel and one to the electric heater fed from a
single field supplied disconnect.
Field Connection
A high voltage connection hole is located on the outside of
the unit with knock-out; see submittal drawings for location.
A field installed disconnect switch must use a liquid-tight
connector between the disconnect switch and the outside
panel of the unit eliminating any water penetration into the
control box. A wiring diagram is located within the control
panel area of the unit.
A low voltage Field Wiring (FW) interface is provided near
the control Panel (PNL) terminals for shipped loose or field
supplied controls, sensors or interlock connections. The
location of the field wiring and panel terminals may vary
depending upon options selected as illustrated in Figure 2.
The low voltage field wiring entry is made through the side
of the unit below the input power supply connection (see
Appendix G ) which runs through the outside casing and
requires a liquid-tight connector or conduit to avoid water
penetration.
Installer must provide wiring for controls that are supplied
optionally and shipped loose or field supplied. All field sup-
plied low voltage wiring must be Class 2. Mark the Field
Wiring terminals schematic ( Appendix G ) with the con-
nections completed and leave with the unit for start-up and
service.
Units will require a start contact interlock from a remote
time clock, light sensor, occupancy sensor, manual selec-
tor switch or remotely through BACnet from a Building
Management System (BMS) depending on ventilation
control scheduling mode required. Select required inter-
lock and ventilation control scheduling mode from descrip-
tion below.
See
Appendix F and Appendix G for wiring terminal con-
trol diagram examples and standard Field Wiring (FW) ter-
minal and interlock connections available.
Units Supplied with DDC Control Package
The DDC control package enables stand alone opera-
tion of the VHC unit and includes a factory installed, pro-
grammed and run tested stand alone microprocessor
based controller, all necessary sensors and interfaces to
provide control of optional post conditioning functions. See
the VHC-36, 42 and 50 DDC Control Package Manual
(VCES-DDC-IOM-1 (500020459)) for overview, installation
and start-up.
An intelligent programmable interface device (BacStat II)
with built in room sensor is included for communication,
display, setpoint control and to allow for servicing and is
shipped loose for field wiring and installation at the unit or
remotely. Determine required location for installation and
connect using two twisted pair cables, the first for power
connection. The LinkNet cable needs to be balanced 100
to 120 ohm nominal impedance twisted shielded pair cable,
nominal capacitance of 16 PF/FT or lower.
Units Supplied with an Electro-mechanical
Controls (EMC) Package
The EMC controls package or dry contact control option
include: all relays, motor starters, motor overloads, damper
actuators, heating and cooling initiate contacts and se-
lected option pickup points. All necessary connections are
wired to a terminal strip in the control panel for field wiring
connections to a Building Management System (BMS), for
field supplied DDC or standard controls and thermostats.
See the Control Contractor’s flow and wiring schematics
for connection details.
Ventilation Control Scheduling Modes
Occupied Ventilation (Ov)
If the occupancy contact closes or a jumper is placed
across terminals FW 304–305 this will enable the unit to
run in 100% fresh air mode. Free cooling and defrost will
initiate based on the setpoint.
Unoccupied Recirculation (Ur)
If the unoccupied recirculation contact closes or a jumper
is placed across terminals FW 305–306 the unit will turn off
unless there is a call for heating/cooling or dehumidification
across the heating/cooling or dehumidification contacts.
Electrical Connections
WARNING
When installed, the appliance must be electrically
grounded in accordance with local codes or, in the ab-
sence of local codes, with the National Electrical Code,
ANSI/NFPA70, and/or the Canadian Electrical Code CSA
C22.1. Unit cabinet must have an uninterrupted, unbroken
electrical ground to minimize the possibility of personal
injury if an electrical fault should occur. Failure to follow
this warning could result in the Installer being liable for
personal injury of others.
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