d. Cooling thermostat R-to-G-and-Y for single-speed cooling blower.
8. Reinstall control doors on both furnaces.
9. Instruct user in operation of furnace and thermostat.
PROCEDURE 8—SEQUENCE OF OPERATION
See Fig. 13, 14, or 15 and 18 or 19 for single-speed non-condensing furnace twinning connection and schematic wiring diagrams while reviewing
the sequence of operation.
Twinning operation is controlled by LH furnace. The TWIN/TEST and C
OM
24v connection wires ensure the 2 furnaces coordinate their blower
operation. When either furnace requires blower operation, both furnaces operate their blowers at the same speed. Both furnaces operate
simultaneously in the same mode: heat, cool, or continuous fan. Exceptions can occur if a safety switch on either furnace is activated (such as
pressure switch, flame roll-out switch, main limit switch, draft safeguard switch, twinning kit auxiliary limit switch, or flame-proving sensor). In
such a case, the other furnace continues to operate unless open switch is the flame roll-out, main limit, or twinning kit auxiliary limit switch, in
which case both furnaces respond.
Before performing component test, disconnect TKR yellow wire labeled TEST from LH furnace control TEST/TWIN terminal. After removing
yellow wire, component test can be initiated on each furnace individually as stated in Installation, Start-Up, and Operating Instructions.
Single-Stage Heat with Single-Stage Gas-Heat Thermostat
See Section I, Procedure 2 for furnace and kit components used.
1. Single-stage thermostat causes both furnaces to operate in heating mode.
2. Operation in ALL modes is the same for twinned furnaces as for an individual furnace. See furnace Installation, Start-Up, and Operating
Instructions for more information on sequence of operation.
Two-Stage Heat with 2-Stage Gas-Heat Thermostat
Fig. 16—Single-Stage Furnace Control
A02142
BL
W
NUETRAL
ST
A
TUS CODE LED
SEC-2 SEC-1
EAC-2 L2
FUSE 3-AMP
0.5 AMP@24VAC
HUM
TEST/TWIN
Y1 DHUM G COM
W/W1
Y/Y2 R
24V
PL
T
120 180
90 150
BLOWER OFF-DELAY
PL
T 1
COOL HEA
T
SPARE-1 SPARE-2
FAN
EAC-1
1-AMP@
115VAC
PR-1
L1
PL2 1
24-V THERMOSTAT
TERMINALS
3-AMP FUSE
LED OPERATION &
DIAGNOSTIC LIGHT
115-VAC(L2)NEUTRAL
CONNECTIONS
COOL
HEAT
SPARE-1
SPARE-2
FAN
BLOWER SPEED
SELECTION TERMINALS
EAC-1 TERMINAL
(115-VAC 1.0 AMP MAX.)
115 VAC (L1) LINE
VOLTAGE CONNECTION
PL2-HOT SURFACE
IGNITER & INDUCER
MOTOR CONNECTOR
PL1-LOW VOLTAGE MAIN
HARNESS CONNECTOR
TRANSFORMER 24-VAC
CONNECTIONS
HUMIDIFIER TERMINAL
(24-VAC 0.5 AMP MAX.)
TWINNING AND/OR
COMPONENT TEST
TERMINAL
BLOWER OFF-DELAY
—21—
