Page 29
Cleaning the Burners
NOTE - Use papers or protective covering in front of the fur
nace during cleaning.
1 - Turn off both electrical and gas power supplies to fur
nace.
2 - Label the wires from gas valve, rollout switches, prima
ry limit switch and make-up box then disconnect them.
3 - Disconnect gas supply piping. Remove the screw se
curing the burner box cover and remove cover. Re
move the four screws securing the burner manifold as
sembly to the vestibule panel and remove the
assembly from the unit.
4 - To clean burners, run a vacuum cleaner with a soft brush
attachment over the face of burners. Visually inspect in
side the burners and crossovers for any blockage
caused by foreign matter. Remove any blockage. Figure
33 shows burner detail.
5 - Reinstall burner box, manifold assembly and burner box
cover.
6 - Re-install gas supply and turn on electrical pwer to fur
nace.
Twinning 2 80AF1UH Furnaces
The control board in this furnace is equipped with a provi
sion to ”twin” (interconnect) two(2) adjacent furnaces with a
common plenum such that they operate as one (1) large
unit.
When twinned, the circulating blower speeds are synchro
nized between the furnaces. If either furnace has a need to
run the blower, both furnaces will run the blower on the
same speed. The cooling speed has highest priority, fol
lowed by heating speed and fan speed.
Field installation of twinning consists of connecting wires
between the ”C” and ”Twin” terminals of the two controls.
The 24 VAC secondary of the two systems must be in
phase. All thermostat connections are made to one control
only. Figure 34 show wiring for two-stage and single stage
thermostats.
The twinned furnace without thermostat connections is to
have the call for heat supplied by an external 24VAC isola
tion relay to prevent its rollout switch from being bypassed
by the other twinned furnace. The coil of the isolation relay
connects from the thermostat ”W” to 24 VAC common. The
contacts of the relay connect ”R” to ”W” on the non-thermo
stat twin.
80AF1UH BURNER ASSEMBLY & REMOVAL
FIGURE 33
Manifold And Gas Valve
Retention Rings
Cross Over
Ignitor
Rollout Switches
(-090, -110 -135 units)
Sensor
Rollout Switches
(-045 and -070 units)
