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Guardian with Smart Sense™
Owner’s Manual • Guardian
23
FIG. 20
Manual Reset High
Limit Switch
WARNING
Fire Hazard
■ Do not operate the heater with the high limit
switch bypassed.
■ Operating the heater a bypassed high limit
switch may lead to overheating, possibly result-
ing in a fi re, with subsequent damage to the
heater, building damage, or loss of livestock.
This heater uses a high limit heat switch for the purpose of
over heat protection. The high limit switch is located on the
heat chamber. See Figs. 21, 22 or 23 for location depend-
ing on model. The high limit switch is connected in series
between the ignition control and the gas control valve.
The switch has normally closed contacts. If an overheat
condition occurs, the switch contacts will open, thereby
opening the circuit to the gas control valve. The high limit
switch should be tested a minimum of once per year when
the heater is given a thorough cleaning.
1. Remove the switch. Holding the switch by one of its
mounting legs, apply a small fl ame only to the sensing
portion on the back of the switch. See Fig. 24. Do not
melt the plastic housing of the switch when conducting
this test.
2. Within a minute, you should hear a soft “click” of the
switch contacts opening. Check for lack of electrical
continuity across the switch terminals to verify
contacts have opened.
3. Allow the switch cool down for about a minute before
fi rmly pressing the reset button on the switch. (If the
switch has a red vinyl cover over the reset button,
remove the cover, then
fi rmly press the reset.)
4. Check for electrical continuity across the switch
terminals to make sure the contacts have closed.
5. Reinstall the switch back into the heater. Ensure red
vinyl cover is installed, if applicable. Reconnect the
heater to its electrical supply. Start the heater and
check for proper operation.
FIG. 21
FIG. 22
AD060 / AW060
AD100 / AW100