MOUNTING AND WIRING
NOTE: All wiring should be installed according to local and
national electrical codes and ordinances. Additional wiring
extensions are included in the kit if the original wires do not
reach the IFC.
1. Disconnect electrical power and gas supply to unit, then
remove unit access panels.
2. Mark and disconnect all wires from the existing control,
then remove existing control.
NOTE: If there is an 80V ignitor currently installed, you must change to the 120V ignitor using the 789A-820 Ignitor
Kit and Ignitor Adapter Harness. See box for a list of controls requiring this change.
MOUNTING OPTIONS
A
B
3. Mount the new control board in the unit and reconnect all
the wires. Secure any wiring as necessary.
4. Reinstall unit access panels and reconnect electric power
and gas supply to the unit.
5. Verify unit operation by placing thermostat in heating
mode and initiating a call for heat by adjusting thermostat
5 degrees above room temperature.
A
Standoffs
Press standoffs into board and mount unit.
B
Corner Drill Holes
Press control into cover until it clicks into place on both sides.
Use care when drilling screws.
NOTE: Be careful of electrostatic discharge when
handling the control board.
INSTALLATION
3