Sequence Of Operation - Trane 4DCY4024 Installer's Manual

Installer's Guide

Has the heating air temperature rise been checked?

Has the unit been checked for tubing and sheet metal rattles?
Are there any other unusual noises to be checked?

Are all covers and panels in place and properly fastened?
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Has the owner been instructed on the proper operation and
maintenance of the unit? Be sure to leave this manual with the
owner.

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 op-
eration while the AUTO setting provides indoor blower operation
during the compressor heating and cooling cycles. Continuous
fan mode during cooling operation may not be appropriate 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 4DCY4 units require either a *CONT402,
*CONT802 or *CONT803 Comfort Control. Do not install any
other model of thermostat with this 4DCY4 unit. Otherwise,
mis-operation could result due to the dual fuel nature of this
unit. Note: A BAYSENS02ATEMPA outdoor temperature
sensor must be purchased separately and installed in order
to use the *CONT802 and *CONT803 Comfort Controls with
this unit. A BAYSEN01ATEMPA outdoor sensor is shipped
with the *CONT402.
NOTE: A field installed jumper wire (18 AWG minimum
conductor) is required between the W1 and W2/X2 low
voltage wires at the 4DCY4 unit when using the *CONT802
or *CONT803 Comfort Controls since these two controls
produce only a W1 output for auxiliary heat. This will result
in low fire gas heating for 10 minutes or for as long as W1
is present if less than 10 minutes. Then, if the W1 signal is
still present from the Comfort Control, the 4DCY4 unit will
transition automatically to high fire and operate on high fire
for the remaining duration of the call for auxiliary heat.
NOTE: The JP1 Dual Fuel jumper wire on the printed circuit
board of the *CONT402 must be cut for proper and reliable
operation of this dual fuel 4DCY4 unit. There is no jumper to
cut on the *CONT802 and *CONT803 Comfort Controls
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. 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
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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. As
in the 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
changeover point 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