CAUTION: UNIT DAMAGE HAZARD
Failure to follow this caution could result in intermitted furnace operation and unit damage.
Supply-air temperature will be uneven left-to-right when only main system is operating.
NOTE:
ALL other 2-stage thermostat connections are to be made to LH furnace control ONLY. (See Fig. 14.)
2B. All Two-Stage Models: 58CTA, 58CTX, 312AAV, 312JAV Multipoise Two-Speed Non-Condensing HSI Furnaces with PSC Motors
WARNING: FIRE HAZARD
Failure to follow this warning could result in fire, personal injury or death.
Make no connections between the R 24-vac connector in 1 furnace and the R 24-vac connector in other furnace.
See electrostatic discharge precaution on page 4.
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. (2) 4 wire polarized wiring harness
d. (2) 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 TKR 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.
Fig. 11—Auxiliary Door Switch
A02251
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