Page 23
3-Flame Rollout Limits S47
limits located just above the burner air intake opening
the ignition control immediately closes the gas valve.
Limit S47 is factory preset to open at 290
o
+ 12
o
+
limits are manual reset.
4-Primary High Temperature Limit S10
S10 is a SPST N.C. high-temperature primary limit for gas
heat in all units. S10 is located next to the blower. See
Primary limit S10 is wired to the ignition control A3. Its
N.C. contacts open to de-energize the ignition control
when excessive temperature is reached in the blower
will be energized by ignition control A3. Three limits with
Use appropriate limit when replacement is required.
S10 LIMIT LOCATION
FIGURE 13
5-Combustion Air Prove Switches S18
Prove switch S18 is a SPST N.O. switch located to the right
of the induced draft assembly. S18 monitors combustion
air inducer operation. Switch S18 is wired to the ignition
control A3. The switch closes on a negative pressure fall.
This negative pressure fall and switch actuation allows the
combustion air inducer is operating before allowing the gas
set and is not adjustable. The switch will automatically
3 shows prove switch settings.
TABLE 3
S18 Prove Switch Settings
+ +
6-Combustion Air Inducers B6
Combustion air inducers on KGC units provide air to the
corresponding burners while clearing the combustion
chamber of exhaust gases. The inducer begins operating
immediately upon receiving a thermostat demand and is
The inducer uses a 208/230V single-phase PSC motor
autoreset overload protection. Inducers are supplied by
control A3 initiates the heating cycle. A3 then allows 30
seconds for the combustion air inducer to vent exhaust
gases from the burners.
the combustion air inducer is operating before allowing
end of the eight-second trial for ignition. All combustion
air inducer motors are sealed and cannot be oiled. The
cleaning.
7-Combustion Air Motor Capacitors C3
The combustion air inducer motors in all KGC units require
run capacitors. Capacitor C3 is connected to combustion
combustion air motor nameplate.
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