Haier GE NF96DS Service Manual page 10

SENSOR
Flame Rollout Switches (Figure 5)
Flame rollout switches S47 are SPST N.C. high temperature
limits located on the left and right of the front buner box plate.
S47 is wired to the burner ignition control A92. When either
of the switches sense flame rollout (indicating a blockage in
the combustion passages), the flame rollout switch trips, and
the ignition control immediately closes the gas valve. Switch
S47 in all NF96DS units is factory preset to open at 210 F
+ 12 F (99 C + 6.7 C) on a temperature rise. All flame rollout
switches are manual reset. See flash code 8 in Table 4 for
troubleshooting.
Flame Sensor (Figure 5)
A flame sensor is located on the left side of the burner support.
The sensor is mounted on the front burner box plate and the
tip protrudes into the flame envelope of the leftmost burner.
The sensor can be removed for service (use steel wool only
to clean) without removing any part of the burners. During
operation, flame is sensed by current passed through the
flame and sensing electrode. The ignition control allows the
gas valve to remain open as long as flame signal is sensed.
NOTE: The NF96DS is polarity sensitive. Make sure that the
furnace is wired correctly and is properly grounded.
IGNITOR
ROLLOUT SWITCHES
Figure 5. Burner Box Assembly
BURNERS
FRONT BURNER BOX PLATE
GAS VALVE
A microamp DC meter is needed to check the flame signal
on the integrated control.
Flame (microamp) signal is an electrical current which
passes from the integrated control to the sensor during unit
operation. Current passes from the sensor through the flame
to ground to complete a safety circuit.
Heat Exchanger (Figure 6)
NF96DS units use an aluminized steel primary and stainless
steel secondary heat exchanger assembly. Heat is transferred
to the air stream from all surfaces of the heat exchanger. The
shape of the heat exchanger ensures maximum efficiency.
The combustion air inducer pulls fresh air through the burner
box. This air is mixed with gas in the burners. The gas / air
mixture is then burned at the entrance of each clamshell.
Combustion gases are then pulled through the primary and
secondary heat exchangers and exhausted out the exhaust
vent pipe.
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