Air Proving Switch; Manual Reset High Limit Switch - L.B. White Therma Grow HW120 Manuel De L'utilisateur

AIR PROVING SWITCH

1. Remove two sheet metal screws holding air proving
switch blower housing. Remove assembly by turning
switch assembly 90 degrees so the switch paddle
can be pulled through oblong hole on side of fan
housing. See Fig. 13.
2. Disconnect the leads from the air proving switch.
3. Use care when installing the replacement switch
(includes cover bracket), to prevent bending of switch
arm which may create ignition problems.
TESTING THE MANUAL RESET HIGH LIMIT SWITCH
Fire Hazard
n
Do not operate the heater with the high limit switch
bypassed.
n
Operating the heater with a bypassed high limit
switch may lead to overheating, possibly resulting in
a fire, with subsequent damage to the heater,
building damage, or loss of livestock.
The high limit switch should be tested a minimum of once
per year when the heater is given a thorough cleaning.
1. Remove the high limit switch from the heat
chamber.
2. Holding the switch by one of its mounting legs or
electrical terminals, apply a small flame only to the
sensing surface on the back of the switch. 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.
18
WARNING
FIG. 13
SWITCH W/ PADDLE
HOUSING SIDE
PANEL
LEADS
4. Allow the switch cool down for about a minute
before firmly pressing the red reset button on the
switch.
5. Check for electrical continuity across the switch
terminals to make sure the contacts have closed.
6. Reinstall the switch back into the heater.
FIG. 14
RESET BUTTON
TERMINAL
MOUNTING
LEG
NUTS
PADDLE
OBLONG HOLE
SENSING
SURFACE
FLAME