Haier GE NF97UM Service Manual page 28

Flame Rollout Switches
Flame rollout switch S47 is a high temperature limit located
inside the burner box. Each furnace is equipped with two
identical switches. The limit is a N.C. SPST manual-reset
limit connected in series with the primary limit S10. When
S47 senses rollout, the circuit breaks and the integrated
control immediately stops ignition and closes the gas valve.
If unit is running and flame rollout is detected, the gas valve
will close and integrated control will be disabled. Rollout
can be caused by a blocked heat exchanger, flue or lack
of combustion air. The switch is factory set to trip (open) at
210°F and cannot be adjusted. The switch can be manually
reset. To manually reset a tripped switch, push the reset
button located on the center of the switch.
Burners
All units use inshot burners. Burners are factory set and
require no adjustment. Always operate the unit with the
burner box front panel in place. Each burner uses an orifice
rollout switch
flame sensor
burner box front cover
(remove screw to open cover)
intake air collar
sight glass
Figure 14. Burner Box Assembly
Page 28
that is precisely matched to the burner input. Burners can
be removed as a one piece assembly for service. If burner
assembly has been removed, it is critical to align center of
each burner to the center of the clamshell when re-installing.
See more detail in Maintenance.
Heat Exchanger (Figure 15)
NF97UM 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.
burner assembly
ignitor
31-5000723 Rev. 0