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Operating Options
The furnace is shipped from the factory in a “Standard Heating Mode” (all switches are in the Down position). When the thermostat
calls for heat, the automatic controls will be activated and the furnace turned “ON”.
The blower will run at low speed or higher speed (as selected by
SPEED SELECTOR
switch).
As the furnace heats up, it automatically switches to the pre-programmed heating speed when additional elements are activated by
the electronic control, if it was initially set to run at low speed. The timing of this blower speed change will depend on whether C
OLD
or M
ILD
is selected on the
SEASON SELECT
switch.
You may, however, change from the Standard Heating Mode by using the controls built into your furnace.
The
SPEED SELECTOR
switch is used to control the fan speed
(ventilation). Even if there is no call for heat, the ventilation can
be controlled by the thermostat; the fan speed is determined by
this switch.
H
IGH
– The blower motor will operate at low speed.
L
OW
– The blower motor will operate at a higher speed.
During spring and fall, you may not require full heating capacity
to maintain a comfortable temperature.
M
ILD
– Approximately half of the elements are “off-line” and will
not be energized when the thermostat calls for heat.
C
OLD
– All elements are “on-line” and controlled by the
thermostat.
NOTE: If outdoor or two-stage thermostat is used, switch MUST
be in MILD position at all times. This switch has no effect on the
10 kW model.
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Breakers
ECM Series furnaces are equipped with breakers, located on
the front panel of the unit. These devices protect the heating
elements from overcurrent. If this situation occurs, the breakers
will open to cut the power from the heating elements only.
NOTE: The number of breakers varies according to the
furnace model; 21ECM10 model has no breakers, 21ECM15,
21ECM18 and 21ECM20 models have 2 breakers, and
21ECM23 and 21ECM25 models have 3 breakers. Refer to
Section 8 Wiring Diagrams.
WARNING
Breakers do not cut power to entire furnace, only to the heating elements. Do not use the breakers to turn off the furnace. The
power to the whole unit can only be cut from the main electrical panel.
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