L.B. White 170 Tradesman Portable Forced Air - Manual (Page 14)

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1. Loosen the compression nut at the outlet of the
variable rate valve. See Fig. 13.
2. Remove both screws securing the valve bracket to
the heater side panel.
3. Remove the valve assembly from the heater and
replace components as needed.
FIG. 13
VARIABLE RATE VALVE AND GAS CONTROL VALVE
SCREWS
COMPRESSION NUT
VARIABLE RATE VALVE
GAS CONTROL VALVE
There are two auto reset limit switches on this heater.
One is located on the burner plate. The other is located
on the underside of the combustion chamber. Either
will cut off power to the gas control valve if the heater
should overheat.
Switch mounted on burner plate. See Fig. 10.
-- Remove the screws, spacers and nuts holding the
switch to the burner plate.
FIG. 10
Switch mounted on underside of combustion
chamber. (See Fig. 11.)
-- Remove base bottom of heater.
-- Remove screws securing the limit to the
underside of the combustion chamber.
-- The combustion chamber is stamped with the
letters P (Propane) and N (Natural gas) adjacent
to the screw holes to identify limit switch location
for the appropriate gas.
FIG. 11
TESTING
The switches should be tested annually.
1. Remove the appropriate switch. Apply a small,soft
flame to the sensing disk of the switch. See Fig. 12.
Be careful not to melt the switch’s plastic housing
when conducting this test.
2. Within a short time, you should hear the contacts of
the switch opening. Check for continuity across
terminals to ensure the switch has opened.
3. Allow the switch to cool. The switch contacts will close.
Check for electrical continuity across the switch
terminals to ensure contacts have closed.
FIG. 12
AUTO RESET LIMIT SWITCHES
LIMIT
SWITCH
NUTS,SCREWS,
SPACERS
P
N
HEIGHT ADJUSTMENT LEG