Page 26
Installer’s Guide
*CONT802 and *CONT803 Operational Differences
from the above sequence:
NOTE:
Unlike the *CONT402, these two controls will not call
for the furnace to operate when the outdoor temperature is
above the selected outdoor temperature changeover point
even if the heat pump capacity is not enough to maintain the
indoor temperature at the desired heating setpoint. If it is
anticipated that the installer selected
outdoor temperature
changeover point from heat pump to furnace must be set
to a temperature at or below where this occurs, then the
*CONT402 control must be used instead of the *CONT802 and
*CONT803 Comfort Controls.
These two controls are not able to cycle on first stage gas heat
in the same way as the *CONT402. The *CONT402 can cycle
the gas heat on and off to
maintain the indoor temperature at
the desired heating setpoint without transitioning to heat pump
operation each cycle if the building load is relatively high. These
two controls will cycle on first stage gas heat by alternating
between gas heat and heat pump operation.
These two controls
may take up to 25 minutes to transition between heat pump and
gas operation.
These two controls require a field installed jumper wire between
the W1 and W2/X2 low voltage wires at the 4DCZ6 unit since
these two controls produce only a W1 output for auxiliary heat.
This jumper will result in low fire gas heating for 10 minutes
or for as long as W1 is present if less than 10 minutes during
auxiliary heating. Then, if the W1 signal is still present from the
Comfort Control, the 4DCZ6 unit will transition automatically to
high fire and operate on high fire for the remaining duration of the
call for auxiliary heat. During Emergency Heat mode operation
these two controls will first energize X2 on a call for heat and
will potentially energize W1 as well. In contrast, the *CONT402
Comfort Control will first energize W1 on a call for Auxiliary or
Emergency Heat mode and will potentially energize W2 as well
as required by the building load.
DEMAND DEFROST OPERATION
During the heating cycle, the outdoor coil may require a defrost
cycle which is determined by the demand defrost control (DFC).
This control continuously measures the outdoor coil temperature
(CBS) and the outdoor ambient temperature (ODS-B) and
calculates the difference or delta-T measurement. An initiate
delta-T is calculated based on the delta-T measurements
obtained after defrost terminates (when the outdoor coil should
be clear of frost). When the measured delta-T during heating
operation reaches the calculated initiate delta-T, the demand
defrost control (DFC) opens the circuit to the outdoor fan motor
(ODM) and energizes the switch-over valve (SOV), placing the
unit in the cooling mode to defrost the outdoor coil. The outdoor
coil temperature sensor (CBS) terminates the defrost cycle,
or times off after twelve, fifteen, or twenty minutes in defrost,
the (DFC) energizes the outdoor fan motor (ODM) and fifteen
seconds later de-energizes the (SOV), which returns the unit
to the heating mode. Supplementary gas heat is brought on to
control indoor temperature during the defrost cycle.
Safety Sequences
This product is equipped with the following devices.
The temperature limit switch (TCO) is located on the blower
barrier, and can be accessed through the blower compartment.
This automatic reset device protects against excessive supply air
temperature. If this device opens, the gas valve is immediately
closed and will not permit operation until the limit switch closes.
The rollout switch (RO) is located in the gas compartment near
the inlet of the burners. This is a manual reset device designed to
protect against any form of flame rollout. If this device is opened
the gas valve is immediately de-energized and the control (IGN)
will lockout the system. The rollout switch (RO) must be reset
before operation is allowed to continue.
The pressure switch (PS) is located in the upper right side of
the gas compartment. This automatic device assures adequate
combustion air pressure. If pressure against the induced draft
blower outlet becomes excessive, the pressure switch will react
and shut off the gas valve, until acceptable combustion pressure
is again available.
If the control (IGN) does not sense flame within the first trial
for ignition period, the gas valve will be de-energized. The
control (IGN) will initiate a 60-second interpurge. Following the
interpurge, the control will perform a second ignition attempt. If
the second try is not successful, the control will start another
60-second interpurge. After the interpurge a third attempt will be
tried. If the third try is not successful, the control will lock out.
If loss of flame occurs during a heating cycle, the control (IGN)
will close the gas valve and cycle through the ignition trial as
stated above.
If control lock out occurs, the control (IGN) will retry a complete
ignition sequence in 1 hour.
The control (IGN) can be reset by removing power to the unit or
by turning the thermostat from ON to OFF for approximately three
seconds, then back ON.
Summary of Contents for 4DCZ6036
Page 5: ...Page 5 Installer s Guide Figure 2 4DCZ6036 2 of 3...
Page 6: ...Page 6 Installer s Guide Figure 3 4DCZ6036 3 of 3...
Page 7: ...Page 7 Installer s Guide Figure 4 4DCZ6048 through 4DCZ6060 1 of 3...
Page 8: ...Page 8 Installer s Guide Figure 5 4DCZ6048 through 4DCZ6060 2 of 3...
Page 9: ...Page 9 Installer s Guide Figure 6 4DCZ6048 through 4DCZ6060 3 of 3...
