2-506.14
OPERATION
Figure 9.1 - Cutaway of Electric Unit Heater
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Operating Sequence
The operation of Modine electric unit heaters is governed by
an electrical contactor which is controlled by a thermostat. The
contactor completes the electric circuit to the heating elements
when the thermostat “calls” for heat. The fan motor is also
activated when the thermostat “calls” for heat.
When the thermostat is satisfied, the fan motor stops and the
contactor opens the circuit to the heating elements.
Prior to Operation
Although this unit has been inspected and tested at the factory,
the following procedures should be performed to assure proper
on-site operation.
1. Check fan clearance. Fan should not contact casing or fan
guard when spun by hand.
2. Check all electrical connections to be sure they are secure,
and in accordance with the wiring diagram.
3. Check firmness of unit suspension. Tighten all fasteners, if
necessary.
4. Make sure fuses are installed in units that require them.
Safety Devices
The overheat control, (See Figure 9.1), will interrupt power to
the unit contactor in the event of overheating. It is a single-pole
single-throw switch, with an automatic reset. The switch will
permit the motor to continue operation and cool the heater while
power to the elements is interrupted. This overheat control
should operate only when something is seriously wrong
with the unit. When this control operates, correct the
difficulty immediately or serious and permanent damage
may result.
The motor for the circulating air fan has internal thermal
overload protection. If for any reason, the motor overheats,
the thermal protector will shut it off. The motor will re-start
automatically when it has cooled.
Initial Start-Up
1. Adjust room thermostat above room temperatures.
2. Turn on power to the unit.
3. Adjust the air deflector (if provided) for desired heat
distribution.
4. Run the unit through several cycles by raising and lowering
the thermostat setting to assure proper sequence of
operation. For Models VE and PTE300, 400, 500 with
two-stage thermostats, check operation on both states.
Three elements should heat up during first stage operation
when temperature falls. As additional heat is required
the remaining three elements will be energized until the
thermostat high-stage setting is satisfied. The unit will
automatically shut off when the low-stage thermostat setting
is satisfied.
1. Side terminal box
2. Power junction box
3. Heating elements
4. Motor heat shield
5. Element support
6. Protective screen
7. Overheat control
8. Fan and motor
9. Outlet fan guard
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