RESET BUTTON
SENSING
SURFACE
TERMINAL
FLAME
MOUNTING
LEG
TESTING THE MANUAL RESET HIGH LIMIT SWITCHES
WARNING
Fire Hazard
■
Do not operate the heater with the high limit switch
bypassed.
■
Operating the heater bypassed high limit switch may
lead to overheating, possibly resulting in a fire, with
subsequent damage to the heater or property damage.
19
1.
Remove hose and pipe nipple from control valve inlet.
2.
Open burner end door.
3.
Re m ove s c r ew s f ro m g a s c o n t ro l b r a c ke t a n d
disconnect control valve’s electrical wiring. See Fig.
24.
FIG. 24
4.
Remove burner access panel. See Fig. 25.
FIG. 25
5.
Remove burner retaining bolt from under base at gas
control end of heater. See Fig. 26.
FIG. 26
6. Lift and pivot the gas train assembly so orifice is
exposed. See Fig. 27. Remove control valve or orifice
as needed.
FIG. 27
SCREW
BOLT
BURNER ORIFICE AND GAS CONTROL VALVE
ORIFICE
This heater has two limit switches. One is located at the
burner end of the heater. The other is located on the fan
housing at the motor end of the heater. Their purpose is to
safely shut the heater down if the appliance should
overheat.
Both high limit switches should be tested a minimum of
once per year when the heater is given a thorough cleaning.
1.
Remove the high limit switches.
2.
Holding a switch by one of its mounting legs, apply a
small flame only to the sensing portion on the back of
the switch.See Fig.23. Be careful not to melt the
plastic housing of the switch when conducting this
test.
3.
Within a minute, you should hear a pop coming from
the switch, which indicates the contacts of the switch
have opened.
4.
Allow the switch to cool for about a minute before
firmly pressing its reset button. The switch may have
a red cap over the button. If you removed the cap to
reset the switch, ensure you put it back on.
5.
Check for electrical continuity across the switch
terminals to make sure the contacts have closed.
FIG. 23