Operating instructions

If 2-stage heating thermostat is to be used, move SW-2 to ON
position at end of furnace installation. This overrides built-in
control process for selecting high and low stage and allows 2-stage
thermostat to select gas heating modes. The W2 from thermostat
must be connected to W2 on control terminal block. (See Fig. 16.)
Before operating furnace, check each manual reset switch for
continuity. If necessary, press and release button to reset switch.
CAUTION: This furnace is equipped with 2 manual
reset limit switches in gas control area. The switches will
open and shut off power to gas valve if a flame rollout or
an overheating condition occurs in gas control area. DO
NOT bypass switches. Correct inadequate combustion air
supply, component failure, restricted flue gas passageway
before resetting switches.
B. Sequence of Operation
Using the schematic diagram follow sequence of operation through
different modes. (See Fig. 18.) Read and follow wiring diagram
very carefully.
NOTE: If power interruption occurs during "call for heat" (W/W1
or W/W1-and-W2), control starts 90-sec blower only on period 2
sec after power is restored if thermostat is still calling for gas
Fig 16—Heating and Cooling Application Diagram With 2-Stage Thermostat and Condensing Unit
A99072
115-V FUSED
DISCONNECT
SWITCH
(WHEN REQUIRED)
JUNCTION
BOX
CONTROL
BOX
24-V
TERMINAL
BLOCK
THREE-WIRE
HEATING-
ONLY
SEVEN
WIRE
2-STAGE THERMOSTAT TERMINALS
FIELD-SUPPLIED
FUSED DISCONNECT
2-SPEED
CONDENSING
UNIT
FURNACE
G
R
W2 Y2 G Y1
C
GND
GND
GND
GND
GND
GND
FIELD 24-V WIRING
FIELD 115-, 208/230-, 460-V WIRING
FACTORY 24-V WIRING
FACTORY 115-V WIRING
208/230- OR
460-V
THREE
PHASE
208/230-V
SINGLE
PHASE
Y2
Y1
C
WHT
BLK
WHT
BLK
W1 R
W2
COM
W/W1
Y/Y2
NOTES: 1. Connect Y-terminal as shown for proper operation.
2. Some thermostats require a "C" terminal connection as shown.
3. If any of the original wire, as supplied, must be replaced,
use same type or equivalent wire.
TABLE 7- SETUP SWITCH DESCRIPTION
SETUP
SWITCH NO.
NORMAL
POSITION
DESCRIPTION OF USE
SW-1
Only High-Gas Heat
OFF
(Staged Gas
Heat)
Turn switch on to obtain only
high-gas-heat operation on
any call for heat regardless of
whether R-W/W1, or
R-W/W1, -W2 is closed. SW-1
overrides SW-2.
SW-2
Low-Gas Heat
(Adaptive Algorithm)
OFF
(Single-Stage
Thermostat)
Turn switch off for installations
with single-stage thermostats;
control selects low-gas-heat
or high-gas-heat operation
based on previous cycles.
Turn switch on for installations
with 2-stage thermostats to
permit only low-gas-heat op-
eration in response to closing
R-W/W1. High-gas heat is
supplied only when R to
W/W1 and W2 is closed.
SW-3 and
SW4
ON, OFF
Switches control gas heating
algorithm blower off delay.
(See Table 8.)
TABLE 8—BLOWER OFF DELAY
SETUP SWITCH POSITION
DESIRED HEATING
ALGORITHM OFF DE-
LAY (SEC)
SETUP SWITCH
SW-3 SW-4
90 OFF OFF
135 OFF ON
180 ON OFF
225 ON ON
Fig. 17—Setup Switches on Control Center
(Factory Settings)
A96402
BLOWER-
OFF
DELAY
LOW
HEAT
(ADAPTIVE
ALGORITHM)
HIGH
HEAT
ONLY
43 2
OFF
ON
1
—13—