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SEQUENCE OF OPERATION
Cooling (cooling only or heat pump)
When the thermostat calls for cooling, the circuit between R and
G is completed, and the blower relay is energized. The Normally
Open contacts close, causing the indoor blower motor to
operate. The circuit between R and Y is also completed; this
circuit closes the contactor in the outdoor unit starting the
compressor and outdoor fan motor. Circuit R and O energizes the
reversing valve, switching it to the cooling position. (The
reversing valve remains energized as long as selector switch is in
the COOL position.)
Heating (electric heat only)
When the thermostat calls for heat, the circuit between R and W
is completed, and the heater sequencer is energized. A time
delay follows before the heating elements and the indoor blower
motor come on. Units with a second heat sequencer can be
connected with the first sequencer to W on the thermostat sub-
base or connected to a second stage on the sub-base.
Heating (heat pump)
When the thermostat calls for heat, the circuits between R and Y
and R and G are completed. Circuit R-Y energizes the contactor
starting the outdoor fan motor and the compressor. Circuit R and
G energizes the blower relay starting the indoor blower motor.
If the room temperature should continue to fall, the circuit
between R and W 1 is completed by the second stage heat room
thermostat. Circuit R-W 1 energizes a heat sequencer. The
completed circuit will energize supplemental electric heat (if
applicable). Units with a second heater sequencer can be
connected with the first sequencer to W 1 on the thermostat or
connected to a second heating stage W 2 on the thermostat sub-
base.
Auxiliary Heat (heat pump)
When the thermostat functions to call for auxiliary heat, the heat
pump is turned off. Place a jumper wire between Terminals W2
and E on the thermostat terminal connections. See Heat Pump
Application wiring diagram. This will allow the indoor blower to
cycle on and off with the electric heat when the fan switch is in
the AUTO position.
Variable Speed Features
The EFV electric furnace is equipped with a variable speed motor
and will deliver a constant airflow within a wide range of external
static pressures. The variable speed blower offers the following
comfort features:
Soft Start
When called into operation, the variable speed motor will slowly
ramp up to normal operating speed. This eliminates the noise
and discomfort that results caused by the initial blast of air
encountered with standard electric furnaces. It can take up to 7.5
minutes to reach normal operating speed.
Continuous Blower Operation
The comfort level of the living space can be enhanced when
using this feature by allowing continuous circulation of air in
between calls for cooling or heating. The circulation of air
between calls for cooling or heating occurs at 50% of the normal
airflow rate (350 CFM minimum).
Reduced Airflow Operation
For situations where humidity control is a problem, the variable
speed motor can be enabled to operate at a 10% reduction in the
normal airflow rate under the control of a humidistat. This can be
achieved by connecting to a standard humidity control that is
normally closed and opens on humidity rise.
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