c. Two-Stage Thermostat and Two-Speed Cooling
(See Fig. 30 for thermostat connections)
NOTE:
The air conditioning relay disable jumper ACRDJ must
be disconnected to allow thermostat control of the outdoor unit
staging. (See Fig. 32.)
The thermostat closes the R-to-G-and-Y1 circuits for low-
cooling or closes the R-to-G-and-Y1-and-Y2 circuits for
high-cooling. The R-to-Y1 circuit starts the outdoor unit on
low-cooling speed, and the R-to-G-and-Y1 circuit starts the
furnace blower motor BLWM on low-cool speed (same
speed as LO HEAT). The R-to-Y1-and-Y2 circuits start the
outdoor unit on high-cooling speed, and the R-to-G-and-
Y/Y2 circuits start the furnace blower motor BLWM on
COOL speed.
The electronic air cleaner terminal EAC-1 is energized with
115 vac whenever the blower motor BLWM is operating.
When the thermostat is satisfied, the R-to-G-and-Y1 or
R-to-G-and-Y1-and-Y2 circuits are opened. The outdoor
unit stops, and the furnace blower BLWM and electronic
air cleaner terminal EAC-1 will remain energized for an
additional 90 seconds. Jumper Y1 to DHUM to reduce the
cooling off-delay to 5 seconds. (See Fig. 32.)
4. Thermidistat Mode
(See Fig. 25–27 for Thermidistat connections)
The dehumidification output, DHUM on the Thermidistat
should be connected to the furnace control thermostat terminal
DHUM. When there is a dehumidify demand, the DHUM
input is activated, which means 24 vac signal is removed from
the DHUM input terminal. In other words, the DHUM input
logic is reversed. The DHUM input is turned ON when no
dehumidify demand exists. Once 24 vac is detected by the
furnace control on the DHUM input, the furnace control
operates in Thermidistat mode. If the DHUM input is low for
more than 48 hours, the furnace control reverts back to
non-Thermidistat mode.
The cooling operation described in item 3. above also applies
to operation with a Thermidistat. The exceptions are listed
below:
a. Low cooling - When the R-to-G-and-Y1 circuit is closed
and there is a demand for dehumidification,the furnace
blower motor BLWM will continue running at low-cool
speed (same speed as LO HEAT).
b. High cooling - When the R-to-G-and-Y/Y2 circuit is closed
and there is a demand for dehumidification,the furnace
blower motor BLWM will drop the blower speed from
COOL to HI HEAT for a maximum of 10 minutes before
reverting back to COOL speed. If there is still a demand for
dehumidification after 20 minutes, the furnace control CPU
will drop the blower speed back to HI HEAT speed. This
alternating 10-minute cycle will continue as long as there is
a call for cooling.
c. Cooling off-delay - When the “call for cooling” is satisfied
and there is a demand for dehumidification, the cooling
blower-off delay is decreased from 90 seconds to 5
seconds.
5. Continuous Blower Mode
When the R-to-G circuit is closed by the thermostat, the
blower motor BLWM will operate on continuous-blower
speed (can be set to LO HEAT, HI HEAT, or COOL speed).
Factory default is LO HEAT speed. Terminal EAC-1 is
energized as long as the blower motor BLWM is energized.
During a call for heat, the blower BLWM will stop during
igniter warm-up (17 seconds), ignition (7 seconds), and
blower-ON delay (45 seconds in low-heat, and 25 seconds in
high-heat), allowing the furnace heat exchangers to heat up
more quickly, then restarts at the end of the blower-ON delay
period at LO HEAT or HI HEAT speed respectively.
The blower motor BLWM will revert to continuous-blower
speed after the heating cycle is completed. In high-heat, the
furnace control CPU will hold the blower motor BLWM at HI
HEAT speed during the selected blower-OFF delay period
before reverting to continuous-blower speed.
When the thermostat
″
calls for low-cooling
″
, the blower motor
BLWM will switch to operate at low-cool speed (same speed
as LO HEAT). When the thermostat is satisfied, the blower
motor BLWM will operate an additional 90 seconds on
low-cool speed before reverting back to continuous-blower
speed.
When the thermostat
″
calls for high-cooling
″
, the blower
motor BLWM will operate at COOL speed. When the ther-
mostat is satisfied, the blower motor BLWM will operate an
additional 90 seconds on COOL speed before reverting back
to continuous-blower speed.
When the R-to-G circuit is opened, the blower motor BLWM
will continue operating for an additional 5 seconds, if no other
function requires blower motor BLWM operation.
Continuous Blower Speed Selection from Thermostat –To
select different continuous-blower speeds from the room
thermostat, momentarily turn off the FAN switch or push-
button on the room thermostat for 1-3 seconds after the blower
motor BLWM is operating. The furnace control CPU will shift
the continuous-blower speed from the factory setting of LO
HEAT to HI HEAT speed. Momentarily turning off the FAN
switch again at the thermostat will shift the continuous-blower
speed from HI HEAT to COOL. Repeating the procedure will
shift the continuous-blower speed from COOL to LO HEAT
speed. The selection can be changed as many times as desired
and is stored in the memory to be automatically used follow-
ing a power interruption.
NOTE:
If the blower-off delay is set to the maximum, the
adjustable continuous-fan feature is locked (i.e., fan speed cannot
be changed from its current setting).
6. Heat Pump
(See Fig. 26 through 29 for thermostat connections)
When installed with a heat pump, the furnace control auto-
matically changes the timing sequence to avoid long blower
off times during demand defrost cycles. When the R-to-
W/W1-and-Y1 or R-to-W/W1-and-Y1-and-G circuits are en-
ergized the furnace control CPU will switch to or turn on the
blower motor BLWM at low-cool speed (same speed as LO
HEAT), and begin a low-heat cycle. The blower motor
BLWM will remain on until the end of the prepurge period,
then shut off for 24 seconds then come back on at LO HEAT
speed. When the W/W1 input signal disappears, the furnace
control begins a normal inducer post-purge period and the
blower remains running at LO HEAT speed. If the R-to-
W/W1-and-Y1-and-G signals disappear at the same time, the
blower motor BLWM will remain on for the selected blower-
OFF delay period. If the R-to-W/W1-and-Y1 signals disap-
pear, leaving the G signal, the blower motor BLWM will
remain on for the selected blower-OFF delay period then
switch to continuous-blower speed.
When the R-to-W/W1-and-Y/Y2, R-to-W/W1-and-Y/Y2-
and-G, R-to-W/W1-and-Y1-and-Y/Y2, or R-to-W/W1-and-
Y1-and-Y/Y2-and-G circuits are energized the furnace control
CPU will switch to or turn on the blower motor BLWM at
COOL speed, and begin a high-heat cycle. The blower motor
BLWM will remain on until the end of the prepurge period,
then shut off for 24 seconds then come back on at HI HEAT
speed. When the W/W1 input signal disappears, the furnace
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Summary of Contents for 58CTA
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