Replacing The Safety Limit Switch - Lennox MPB33CNM Care And Operation Instructions Manual

LENNOX HEARTH PRODUCTS • MERIT PLUS
5.
To check for venting action, start by
holding a smoke producing device
within an inch of one side edge (not top
or bottom edge) of the glass enclosure
panel. The smoke should be drawn
toward the edge of the glass enclosure.
Continue the test by moving the smoke
producing device along the entire length
of both side edges of the glass door.
6.
If the smoke is not drawn into the
fi rebox, turn off the appliance and call
a qualifi ed service technician.Resetting
The Safety Limit Switch
This appliance is equipped with a manually
resettable safety limit switch. Refer to Figure 3
for its location. If, during appliance operation,
the flame goes out (independently of the
burner ON/OFF wall switch), it may be due to
a blocked vent. If this condition occurs, the
safety limit switch will activate, causing the
fireplace burner to shut off.
To reset the safety limit switch, perform the
following steps.
NOTE: Allow the appliance to cool
completely.
1.
Remove the top louver panel.
2.
Reset the safety limit switch by pushing
the red reset button located between the
wire terminals on the back of the switch
(See Figure 4, Detail A).
3.
The appliance should then relight and
remain lit.
NOTE: If the appliance does not relight, turn
off the appliance and call for a qualifi ed
service technician to replace the blocked
vent safety limit switch.
4.
Reinstall the top louver panel.

REPLACING THE SAFETY LIMIT SWITCH

To replace the blocked vent safety limit
switch, refer to Figure 3, Details B & C).
NOTE: This procedure should only be
performed by a qualifi ed service technician.
1.
Turn electrical power off before
beginning this procedure.
2.
Lower the bottom control compartment
access panel.
3.
Remove the glass enclosure panel by
unfastening the latch (located in the
center of the unit front opening, under
the fi rebox fl oor) securing the glass
enclosure panel.
4.
Remove the glass enclosure panel by
tilting it outward at the bottom and lifting
it up. Carefully set the door aside to
protect it from inadvertent damage (see
Figure 5 on Page 11).
5.
Remove the three (3) screws securing
the lintel, and then remove the lintel. One
of the lintel cabinet top holes is shown in
Figure 3, Detail B.
6.
Remove the three (3) screws securing
the scoop, and then remove the scoop
(see Figure 3, Detail B).
® B-VENT GAS FIREPLACES (MPB33/35/40/45) • CARE AND OPERATION INSTRUCTIONS
7.
Remove the two (2) screws securing
the safety switch bracket, and remove
the switch/bracket assembly, with low
voltage wires attached, through the side
panel slot into the fi rebox (see Figure 3,
Detail C).
8.
Replace the switch.
9.
Reinstall the switch/bracket assembly.
10.
Reinstall the scoop and lintel.
11.
Reinstall the glass enclosure panel.
12.
Raise the bottom control compartment
access panel.
13.
The appliance should then relight and
remain lit. If this does not occur, check
unit for a blocked vent condition.
Wire
Terminals
Reset Button
Cabinet
Corner
Back Of
Limit
Switch
Door
Frame
Detail A
Lintel Securing Screw
Hole in Cabinet Top
Firebox Top
Scoop
Scoop Securing Screws
Detail B
Lintel Securing-Screw
Firebox Top Hole in Cabinet Top
Limit Switch/Bracket
Securing Screws
Limit Switch
View Without Scoop
Detail C
Blocked Flue Safety Limit Switch Location, Inside
View of Firebox, Top/Right Side Intersection
Figure 3: Safety Limit Switch
OUTSIDE COMBUSTION AIR CONTROLS
Many appliances are equipped with an
outside (make-up air) vent system designed
to provide the appliance with outside make-
up air for combustion while in operation.
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
The combustion air control lever for the
outside air system is standard on all
appliances but should not be operated if
the complete system is not installed (see
Figure 4). When the complete outside
air vent system is installed, the installer
will remove the securing screw from the
combustion air control lever located on the
left side of the bottom fi replace opening.
If the securing screw has not been removed
and you have reason to believe that you have
a complete outside air system, contact your
dealer to have your appliance inspected for
the presence of the complete system.
WARNING
Do not operate the shutoff
lever unless a complete
outside combustion air system
has been installed with
the appliance.
NOTE: Do not assume the outside air vent
system is installed.
To open the outside air shutter complete the
following steps.
1.
Open the bottom control access panel.
2.
Reach into the control compartment and
pull the combustion air control lever all
the way out.
The outside air shutter should be fully open
when the fi replace is in use and completely
closed when the fi replace is not being used.
Closing the air shutter when not in use will
prevent outside cold air from entering the
building.
Outside Air Control Lever
Outside Air Control Lever
Securing Screw
Air Shutter in Closed Position
Outside Air Control Lever
Outside Air Control Lever
Securing Screw Removed
Air Shutter in Open Position
Figure 4: Combustion Air Control Lever
and Securing Screw Location
9