14
443 06 2403 01
Specifications subject to change without notice.
Two
−
Stage Heat with Single
−
Stage Gas
−
Heat Thermostat
(Field Supplied) (See Figure 17).
NOTE
: This application allows both furnaces to operate as 1
furnace in gas heat mode as determined by single
−
stage
thermostat operation. Both furnaces operate in heating mode
simultaneously. See furnace Installation, Start
−
Up, and
Operating Instructions for further details on this heating mode.
1. Install harness labeled “Main Furnace” with TKR on L/H
Furnace: The Main Harness includes the TKR relay and
Auxiliary Limit switch on the harness. The harness is
also tagged “Main Furnace” near the ends of the plug
connector.
a. Secure relay of TKR harness assembly to LH
furnace blower housing using 2 factory
−
supplied
screws. Two new screw holes will have to be drilled
using a 1/8
−
inch drill bit. See Figure 12 for location of
holes to be drilled.
b. Connect TKR white wire labeled W from TKR to LH
furnace control thermostat connection W/W1.
c. Connect TKR black wire labeled C from TKR to LH
furnace control thermostat connection C.
d. Connect yellow wire labeled TEST to LH furnace
control TEST/TWIN terminal.
e. If Extension Harness was used, connect 4
−
wire
harness to Extension Harness.
f. Turn TT set
−
up switch on L/H control board to “OFF.”
g. Turn TT set
−
up switch on R/H control board to “ON.”
NOTE
: If Extension Harness will not plug in to L/H and R/H
furnaces, extension harness is installed backward. Remove
extension harness and re
−
install in correct orientation.
2. Install Auxiliary Limit Switch (ALS
−
M) on L/H furnace:
a. Drill 1/8
−
in. hole in blower housing 12 in. (305
mm)below blower shelf. (See Figure 13)
b. Position ALS
−
M so reset button faces front of
furnace.
c. Secure bracket to blower housing using a
factory
−
supplied screw.
d. Disconnect red transformer wire from LH furnace
control 24 VAC connection.
e. Connect red transformer wire connector to ALS
−
M
wire connector PLC labeled TRAN.
f. Connect ALS
−
M orange wire connector labeled SEC
1 to LH furnace control 24 VAC terminal.
g. If Extension Harness was used, connect 2
−
wire
harness to Extension Harness
3. Install Secondary 4
−
wire harness on R/H furnace:
The Secondary Harness includes the Auxiliary Door Switch
and Auxiliary Limit Switch. The harness is also tagged
“Secondary Furnace” near the plug ends of the harness.
a. Connect red wire labeled R
−
Secondary to RH
furnace control thermostat connection R.
b. Connect white wire labeled W
−
Secondary to RH
furnace control thermostat connection W/W1.
c. Connect black wire labeled C
−
Secondary to RH
furnace control thermostat connection C.
d. Connect yellow wire labeled TEST SECONDARY to
RH furnace control TEST/TWIN terminal.
e. If the furnaces are side
−
by
−
side, route loose ends of
4
−
wire harness from Secondary furnace to Main
furnace through snap bushings previously installed
between furnaces.
f. Connect Secondary 4
−
wire harness into 4
−
wire Main
harness.
g. If Extension Harness was installed, connect 4
−
wire
Secondary Harness to the Extension Harness.
4. Install Auxiliary Limit Switch, ALS
−
S on Secondary
furnace:
a. Drill 1/8
−
in. hole in blower housing 12 in. (305
mm)below blower shelf. (See Figure 13)
b. Position ALS
−
S with terminals facing front of furnace.
c. Secure bracket to blower housing using
factory
−
supplied screw.
5. Install Auxiliary Blower Door Interlock Switch, ILK
−
1 on
Secondary furnace:
NOTE
: This kit contains two auxiliary blower door switch
brackets. Assure that switch bracket used matches bracket
used for factory installed blower door switch.
a. Measure along the left edge of the furnace casing, 6
inches (152 mm) down from blower shelf.
b. Drill a 3/16
−
in. clearance hole through front of blower
door support.
c. Insert blower door switch mounting tab behind blower
door support
d. Secure auxiliary door switch ILK
−
1 using
factory
−
supplied shallow head screw.
e. Connect 2
−
Wire Secondary Harness to 2
−
wire Main
Harness that was routed from Secondary to Main
furnace casings.
f. If extension harness was installed, 2
−
wire Secondary
Harness to Extension Harness.
NOTE
: If Extension Harness will not plug in to L/H and R/H
furnaces, extension harness is installed backward. Remove
extension harness and re
−
install in correct orientation.
6. Select identical blower motor speed taps at control
motor connectors in both furnaces.
UNIT DAMAGE HAZARD
Failure to follow this caution may result in unit damage.
Failure to select identical blower speed taps in both
furnaces can result in overheating of furnace
components and possible loss of furnace operation and
damage to the furnaces
CAUTION
!
7. Dress wires to ensure they do not contact sharp or
moving parts nor interfere with blower operation,
removal of filters, or operation of switches.
8. Make all thermostat connections to LH furnace only.
Two
−
Stage Heat with Two
−
stage Gas
−
Heat Thermostat
(Field Supplied)
NOTE
: ALL thermostat connections are to be made to LH
furnace control ONLY. (See Figure 17)
NOTE
: This application allows both furnaces to operate in low
heat for first
−
stage heat mode or both furnaces to operate in
high heat for second
−
stage heat mode as determined by a
two
−
stage thermostat. See furnace Installation, Start
−
Up, and
Operating Instructions for further details on this heating mode.
To operate furnaces in two
−
stage heating mode when a
two
−
stage thermostat controls the staging, install twinning kit
as described in the two
−
stage heat with single
−
stage gas heat
thermostat:
a. Turn TT set
−
up switch on L/H control board to “ON.”
b. Turn TT set
−
up switch on R/H control board to “ON.”
NOTE
: ALL other two
−
stage thermostat connections are to be
made to LH furnace control ONLY. (See Figure 17)
