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E.
NORMAL SEQUENCE OF OPERATION
1.
The heater must be properly mounted and wired in
accordance with the instructions contained in this
manual. The fan blade must be free to rotate with no
obstruction to air inlet or outlet areas.
2.
Energize the heater at the rated supply voltage.
3.
Assuming that the thermostat calls for heat, i.e. the
thermostat is set to a higher temperature than ambient:
3.1 The main contactor will energize the elements and
the fan motor.
3.2 After the inlet air temperature rises to the set point
of the thermostat, the thermostat contacts will
open and the main contactor will de-energize the
elements and the fan motor.
NOTE:
The large cabinet XGB incorporates a fan delay
feature in both the
“ON”
and
“OFF”
cycles. This is a
desirable feature as it allows the heater to come to
temperature before the fan operates (no cold blasts)
and to cool down the
“OFF”
cycle (longer life for
control components and motor). Delay
“ON”
is 15 to 40
seconds and delay
“OFF”
is 60 to 160 seconds.
4.
The cycle described above will repeat when the ambient
temperature falls below the thermostat set point.
IMPORTANT:
The proper motor/fan rotation, viewed from the
rear of the heater is counter clockwaise for the
small cabinet units and clockwise for the large
cabinet units, as indicated by the fan rotation
label on the heater. Incorrect rotation of the
fan will cause the heater to overheat and cycle
on the high limits. Consult factory in case of
incorrect rotation.
F.
MAINTENANCE
1.
The Norseman™ explosion-proof unit heaters are
designed and constructed to operate in tough industrial
applications with a minimum of maintenance. However,
some routine maintenance is recommended to extend
the life of the heater and its components
Always
disconnect the electrical supply before performing any
maintenance.
2.
Periodically inspect the heater installation to ensure that
all connections, fittings, plugs, screws, covers, etc. are
tight and free of corrosion.
3.
Check the inside of the cabinet and around the element
fins for dust build-up and debris, especially after seasonal
shutdowns. Clean with an air blast or vacuum. Ensure
that nothing is restricting the air flow into the unit and
that the fan blade is free to rotate.
F.1
Motor
The motor supplied with the small cabinet units is approved for
Class 1, Group D, Class II, Group E, F & G, T3B temperature code.
The motor supplied with the large cabinet units is approved for
Class I, Group C & D, Class II, Group E, F & G, T3B temperature
code. All motors have internal thermal protection to eliminate
motor overheating.
F.2 Fan Blade
Visually inspect the fan blade to ensure it is free to rotate and
accidental damage has not occurred. If bent or damaged, a
factory balanced blade should be installed so that the rated
airflow is maintained. A damaged fan blade may not deliver the
required airflow over the elements, resulting in cycling on the
high limit which can significantly reduce the life of the contactor
and the high limit.
F.3 Heater Cabinet
The XGB unit heater cabinet is stainless steel for superior
corrosion resistance. We recommend the cabinet be wiped down
periodically using a mild detergent.
F.4
Overheat Protection
In the event of fan failure, motor damage, excessive dust build-
up or restricted inlet airflow, the heater temperature may rise,
causing the limit controls to open, breaking the power supply to
the heater. All units are equipped with two automatic reset high
limit controls.
Cycling of the high limits should not be permitted.
Should this occur, the unit should be inspected to determine the
cause of the cycling and the condition should be corrected.
