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Installer's Guide
Sequence of Operation
Operation of the unit heating or cooling cycles is controlled by
the mode setting of the room thermostat. Once the system mode
is set to either HEAT or COOL, unit operation is automatic. The
thermostat fan ON setting provides continuous indoor blower
operation at constant circulation airflow of 40-50% nominal of
selected settings while the AUTO setting provides indoor blower
operation during the compressor heating and cooling cycles.
Continuous fan mode during cooling operation may not be ap-
propriate in humid climates. If the indoor air exceeds 60% relative
humidity or simply feels uncomfortably humid, it is recommended
that the fan only be used in the AUTO mode.
NOTE: The 4DCLunits require approved dual fuel comfort
control. Do not install any other model of thermostat with this
4DCL unit. Otherwise, mis-operation could result.
NOTE: See Comfort Control Guide for required sensors &
jumper add or removals.
NOTE: The 4DCL units are equipped with an outdoor
temperature switch to limit gas operation. For outdoor
temperatures above 40 degrees, heating is provided by Heat
Pump operation only. For temperatures 40 and below, heating
may be provided by both gas or Heat Pump operation.
TWO MODES OF OPERATION:
The unit can be installed and configured to operate in one of
two different heating modes: restricted and non-restricted. A
brief explanation of each mode follows.
RESTRICTED: In the restricted mode of operation an outdoor
temperature sensor is used to cause the unit to operate in the
heat pump mode above a selected outdoor temperature and
to operate in the gas heating mode below the selected outdoor
temperature.
NOTE: 4DCL units are equipped with an outdoor temperature
switch to limit gas operation. For outdoor temperatures above
40 degrees, heating is provided by Heat Pump operation only.
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The gas heat will operate with the heat pump when the unit
requires a defrost cycle. The gas heat is used to offset the
effect of the unit going into the cooling mode during defrost.
For the *CONT402, the unit will be commanded to transition
to gas heat even when the outdoor temperature is above
the selected outdoor temperature changeover point if the
heat pump capacity is not enough to
temperature at the desired heating setpoint.
NON-RESTRICTED: This mode of operation allows the unit to
operate in the heat pump mode during the first call, or stage,
of heat commanded by the indoor thermostat. If the heat
pump capacity is sufficient, gas heat will not be required. If
the heat pump capacity is not enough to maintain the indoor
temperature at the desired heating setpoint, the thermostat will
call for the second stage of heat. At that point, the gas heat will
begin to operate and the heat pump will be locked out.
NOTE: 4DCL units are equipped with an outdoor temperature
switch to limit gas operation. For outdoor temperatures above
40 degrees, heating is provided by Heat Pump operation only.
As in restricted mode, the gas heat will act as supplementary
heat during the unit's defrost cycle. See the Field Wiring
Diagram in the Installer's Guide for field wiring instructions.
IMPORTANT: Upon completion of wiring, check all electrical
connections, including factory wiring within the unit. Make
sure all connections are tight. Replace and secure all electrical
box covers and access doors before leaving the unit or turning
on the power to the unit.
NOTE: The outdoor sensor should be located in an area which
will provide a representative outdoor ambient temperature
reading.
The following description applies to the *CONT402. Some of
the operational differences of the *CONT802 and *CONT803
are described at the end of this section.
The following description applies to non-restricted mode.
Restricted operation will be identical except that transitions
from and to first stage (heat pump) heating to and from
second stage (gas) heating can occur, not necessarily as
a result of building load and equipment capacity, but as
determined by the
selected by the installer at the indoor thermostat (see
Restricted Mode description).
Call for 1st stage heating (heat pump):
With the disconnect switch in the ON position, current is
supplied to the compressor crankcase heater, if supplied with
one, and to the control transformer. When the thermostat
calls for first stage heat, power from (R) is switched by
the thermostat to the (Y/Y1) terminal. This powers the
compressor contactor (CC) which starts the outdoor fan motor
and compressor. The thermostat also switches (R) power to
(G) thereby starting the indoor blower motor (IDM).
To maintain the indoor temperature at the desired setpoint,
the thermostat may operate the heat pump continuously or
cycle the heat pump off and on (cycling on 1st stage heat).
maintain the indoor
outdoor temperature changeover point
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