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Section 12:
Electric Heater Packages:
12.1 Principle of Operation
The electric heater is a self-contained duct heater
comprised of:
• Power distribution
• Safety circuits
• Control circuit
• Heating elements
12.2 Operating and Safety Controls
Safety systems are required for proper performance of the
electric heater. The electric heater shall not be permitted
to operate with any safety system disabled. If a fault is
found in any of the safety systems, then the system shall
be repaired only by a contractor qualified in the installation
and service of electric heating equipment, using only
components that are sold and supplied by Addison.
• Air Proving Switch: An air proving switch is provided
as part of the control system to verify airflow across the
elements. If sufficient airflow is not present, indicating
lack of proper air movement through the elements, the
switch opens shutting off the elements. The air proving
switch has fixed settings and is not adjustable.
• Automatic Limit Switch: To prevent operation of the
electric heater under low airflow conditions, the unit
is equipped with a fixed temperature high limit switch
mounted on the vestibule panel. This switch will shut
off heater when the actual discharge air temperature
exceeds the switch's setpoint. Reduced airflow may
be caused by restrictions upstream or downstream
of the circulating air blower, such as dirty or blocked
filters or restriction of the air inlet or outlet to the unit.
12.3 Wiring
All electric wiring and connections, including electrical
grounding, must comply with;
• United States: Refer to National Electric Code®, NFPA
70 - latest revision.
• Canada: Refer to Canadian Electric Code, CSA C22.1
Part 1 - latest revision.
• Check rating plate on unit for supply voltage and
current requirements (located in the control panel
access door of the heater).
• If any of the original control wire supplied with the
electric heater must be replaced, replace it with type
THHN 221° F (105°C), 600 V, 16 gauge wire or equivalent.
• Electric heaters are wired for single point power
termination. Dual point power termination is an
applied special option.
DANGER
ELECTRICAL SHOCK HAZARD
Disconnect electric before service.
More than one disconnect switch
may be required to disconnect
electric from equipment.
Equipment must always be
properly grounded.
WARNING
FIRE HAZARD
Keep all flammable objects,
liquids, and vapors the
minimum required clearances
to combustibles away from
equipment. Some objects will
catch fire, or explode, when
placed close to equipment.
SEVERE INJURY HAZARD
Do not enter equipment while in
operation. Equipment may start
automatically. Do not operate with
access doors open. Installation,
operation, and maintenance
must be performed by a trained
technician only.
BURN HAZARD
Allow equipment to cool before
service. Internal components of
equipment may still be hot after
operation.
CUT/PINCH HAZARD
Wear protective gear during
installation, operation, or
maintenance. Edges are sharp.
Failure to follow these instructions can result in
death, electrical shock, or injury.
Failure to follow these instructions can result in
death, injury, or property damage.
PR Series Installation, Operation, and Maintenance Manual
