34
SAFETY FEATURES
LIMIT CONTROL
The high limit cut-off temperature is set
at the factory and cannot be adjusted.
The temperature setting prevents the
air temperature leaving the furnace
from exceeding the maximum outlet air
temperature, which, if exceeded, will
shut the furnace down.
There are several reasons for a limit
switch to open and almost always
involve low airflow through the furnace.
1. A dirty or restricted air filter.
2. A dirty or restricted cooling coil.
3. Undersized or restricted return air
system.
4. Undersized or restricted supply air
system.
5. A problem affecting the main
blower;
A. A wrong speed tap selection.
B. Failing motor bearings.
C. Low voltage to the motor.
D. Dirty blower wheel.
E. Wrong motor rotation.
F. Blower wheel slipping on the
motor shaft.
6. Overfiring the furnace with too much
gas pressure.
7. Ventilation problems.
FLAME ROLL-OUT
SAFETY SWITCHES
Furnaces are equipped with safety
switches to protect against flame roll-
out conditions in the burner
compartment, which, if tripped, will
terminate the heating cycle. In the
event of a flame roll-out condition, the
switch will shut the furnace down.
Switches for the (-)GPN/(-)GPP
furnaces are located on either side of
the burner cover plate and just above
the burners on the blower divider
panel. If a switch is tripped, it must be
manually rest. DO NOT jumper or
reset this switch. If this switch should
trip, a qualified installer, service agency
or the gas supplier should be called to
diagnose and/or correct the sourse of
tripping. If this unit is mounted in a
closet, the door must be closed when
making this check.
To Next Page
Loading...
