High Limit Switch - L.B.White Guardian AB250 Manual Del Usuario E Instrucciones

High Limit Switch

WARNING
Fire Hazard
■ Do not operate the heater with the high limit
switch bypassed.
■ Operating the heater a bypass high limit switch
may lead to overheating, possibly resulting in
a fire, 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 Fig.25. It is connected between the igni-
tion 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
flame only to the sensing portion on the
back of the switch. See Fig. 26. Do not
melt the plastic housing of the
switch when conducting this test.
2. Within a minute, you should hear a "pop"
coming from the switch, which indicates the
contacts of the switch have opened. 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 firmly pressing the reset but-
ton on the switch.
4. Check for electrical continuity across the
switch terminals to make sure the contacts
have closed.
5. Reinstall the switch back into the heater.
Reconnect the heater to its electrical sup-
ply. Start the heater and check for proper
operation.
Guardian LP or Natural Gas Heater
FIG. 25
FIG. 26
RESET BUTTON
TERMINAL
MOUNTING
LEG
Owner's Manual • Guardian
HIGH LIMIT SWITCH
SENSING
SURFACE
FLAME
23