The twinning kit can be used for single-stage or 2-stage heating operation. There are 3 harness assemblies included in this kit. If the furnaces are
side-by-side, only 2 harness assemblies are required. If the furnaces are installed back-to-back, all 3 harness assemblies included in the kit must
be used.
1. Remove outer doors and blower access doors from both furnaces.
2. If furnaces are installed back-to-back in any orientation, the external Extension Harness must be used. The harness consists of:
a. 54 ½ inches of ½
″
flexible steel conduit
b. (2) 90° conduit connectors
c. (1) 4 wire polarized wiring harness
d. (1) 2 wire polarized wiring harness
3. Install the Extension Harness as follows:
a. Remove lock nuts from the end of each conduit connector.
b. Route the end of the harness, labeled “twinning kit harness,” that mates to the TRK relay harness from the outside of the furnace through
the 7/8
″
knock-out in the casing to the blower compartment.
c. Route the end of the harness that mates to the 4-wire harness through the outside of the furnace through the 7/8
″
knockout in the casing
to the blower compartment.
d. Install the lock nuts on the 90° conduit connectors.
e. Install 2 kit-supplied straps approximately 18 inches from each end of harness.
Single-Stage Heat with Single-Stage Gas-Heat Thermostat (Field-Supplied)
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 control mounting bracket using 2 factory-supplied screws. (See Fig. 10A.)
NOTE:
See Fig. 13 for Single Stage furnace Twinning Kit wiring diagram.
b. Connect TKR white wire labeled W from TKR to LH furnace control thermostat connection W.
Fig. 9b—Suspended Installation for Horizontal Furnaces Stacked Together
A02202
3/8” Threaded Rod
See detail
9” minimum for door removal
Secure angle iron to bottom of
furnace with at least (2) #8 x
3
/
4”
sheet metal screws
1
1
/
2”
x 1
1
/
2”
x 1
1
/
4”
Angle Iron
—12—