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NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

LENNOX HEARTH PRODUCTS  •  MERIT PLUS

®

 B-VENT GAS FIREPLACES (MPB33/35/40/45)  •  CARE AND OPERATION INSTRUCTIONS

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 
swit

ch, 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

)

.

Scoop

Scoop Securing Screws

Firebox Top 

Lintel Securing Screw
Hole in Cabinet Top

Figure 3: Safety Limit Switch

Blocked Flue Safety Limit Switch Location, Inside

View of Firebox, Top/Right Side Intersection

Detail A 

Firebox Top

Limit Switch

Limit Switch/Bracket

Securing Screws

Lintel Securing-Screw

 Hole in Cabinet Top

View Without Scoop

Detail C 

Detail B

Wire
Terminals

Back Of
Limit
Switch

Cabinet
Corner

Door
Frame

Reset Button

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.

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.

Figure 4: Combustion Air Control Lever 

and Securing Screw Location

Outside  Air Control Lever

Outside  Air Control Lever

 Securing Screw

Air Shutter in Closed Position

Outside Air Control Lever

 Securing Screw Removed

Air Shutter in Open Position

Outside  Air Control Lever

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.

 

Summary of Contents for MPB33CNM

Page 1: ...If the information in these instructions is not followed exactly a fire or explosion may result causing property damage personal injury or death s 4 33 7 53 52 3 s 4 4 5 33 5 4 s 6 2 7 2 4 4 5 33 s 5...

Page 2: ...ssure Requirements 7 Orifice Sizes 7 Burn In Period 7 Operation and Care of Your Appliance 8 Gas Controls Control Compartment Access 8 Variable Flame Height Adjustment 8 Vent Operation Test 8 Replacin...

Page 3: ...sez la section Informations importantes relatives la s curit Page 4 Toutes les parties de votre foyer Lennox Hearth Products deviennent EXTR MEMENT CHAUDES Instale una malla o barrera f sica para evit...

Page 4: ...vent subir des br lures s ils viennent en contact avec la surface chaude Il est recommand d installer une barri re physique si des personnes risques habitent la maison Pour emp cher l acc s un foyer o...

Page 5: ...manera 1 Identifique el interruptor de pared que controla la chimenea verifique que el interruptor opera la chimenea encendi ndola y apag ndola Limpie bien la placa del interruptor de pared para quita...

Page 6: ...il fonctionne Ne pas toucher l appareil Risque de br lures graves Surveiller les enfants Garder les v tements les meubles l essence ou autres liquides produisant des vapeur inflammables loin de l app...

Page 7: ...nts used in the manufacturing process Depending on your use the burn in period may take a few hours or a few days KEEP YOUR HOUSE WELL VENTILATED DURING THE CURING PROCESS THE ODOR AND HAZE EMITTED DU...

Page 8: ...racted position and then close the panel Refer to Figure 1 for access to the gas control valve Millivolt appliances will be fitted with the gas control valve shown in Figure 2 MILLIVOLT APPLIANCES To...

Page 9: ...oop Scoop Securing Screws Firebox Top Lintel Securing Screw Hole in Cabinet Top Figure 3 Safety Limit Switch Blocked Flue Safety Limit Switch Location Inside View of Firebox Top Right Side Intersectio...

Page 10: ...cleaning solutions are approved for use to clean glass Non ammonia based household cleaner 50 50 mix of white vinegar and water Gas fireplace stove glass cleaner INSPECT GLASS GASKET Visually inspect...

Page 11: ...only when the front glass enclosure panels are installed Generally the front glass enclosure panel should not be removed except to gain access to the components within the firebox REMOVING GLASS ENCL...

Page 12: ...ent log set in the fireplace will void the warranty and will result in incomplete combustion sooting and poor flame quality Logs get very hot and will remain hot up to one hour after gas supply is tur...

Page 13: ...er end Place the left log and then the smaller left and right top logs All logs that have notches to fit over the grate tines should be positioned with these notches directly against the grate All top...

Page 14: ...osition the right log log no 3 by inserting the pin from the rear log into the hole on its upper end Place the left log and then the smaller left and right top logs All logs that have notches to fit o...

Page 15: ...glowing embers as shown in Figure 6 Place the rear log both the right and left and then the smaller left and right top logs All logs that have notches to fit over the grate tines should be positioned...

Page 16: ...e shutter opening must be adjusted between these two extremes AIR SHUTTER ADJUSTMENT GUIDELINES If there is smoke or soot present first check the log set positioning to ensure that the flames are not...

Page 17: ...to a more open position until the proper flame appearance is achieved If flame remains blue adjust the air shutter incrementally to a more closed position until the proper flame appearance is achieved...

Page 18: ...S VALVES THERMOPILE GAS VALVE If any of the original wire as supplied must be replaced it must be replaced with Type AWM105 C 18 GA wire Thermopile H T P T H T P T TWIST WIRES A AND B TOGETHER TO OPER...

Page 19: ...s switched on TURNING OFF THE APPLIANCE If the appliance and the remote control are switched on when the ON OFF key is pressed Figure 19 the Remote control is turned off The receiver beeps 2 times LOW...

Page 20: ...quipped fireplaces only Rocker Switch Kit 80L41 FRS Forced Air Blower Kit The FBK 100 blower assembly provides con stant velocity forced air circulation The FBK 200 blower assembly provides variable s...

Page 21: ...e in three styles They are easy to install onto the standard glass door frame Includes heavy duty magnetic door latches and functional twin pane doors Cat No Model Description Where Used H8769 AD35B 2...

Page 22: ...s necessary Appliance Checkout Qualified Service Technician Perform the appropriate appliance checkout procedure detailed in this manual Replace Glowing Embers Homeowner Qualified Services Technician...

Page 23: ...ot is lit Release knob and it will pop back up Pilot should remain lit If it goes out repeat steps 5 through 9 If knob does not pop up when released stop and immediately call your service technician o...

Page 24: ...lle s teint r p tez les tapes 5 8 inclusivement Si la manette ne se soul ve pas d elle m me lorsqu on la rel che arr ter et appeler imm diatement un technicien qualifi ou le fournisseur de gaz Si la v...

Page 25: ...me impingement on thermocouple Ensure that the connection between the valve and thermocouple are tight and secure Pilot burning no gas to burner valve knob ON wall switch ON Limit Switch defective Iso...

Page 26: ...h Door Magnetic 69L31 2 69L31 2 69L31 2 69L31 2 8 Log Set Complete 24M15 1 H6197 1 24M25 1 24M25 1 9 Burner Assembly H8585 1 H8585 1 H8587 1 H8587 1 10 Grate Assembly H6526 1 H6526 1 H6314 1 H6314 1 1...

Page 27: ...OT TO SCALE LENNOX HEARTH PRODUCTS MERIT PLUS B VENT GAS FIREPLACES MPB33 35 40 45 CARE AND OPERATION INSTRUCTIONS REPLACEMENT PARTS 7 4 5 14 9 40 45 9 33 35 17 16 10 40 45 33 35 10 12 13 19 18 20 22...

Page 28: ...local distributor for fireplace code information LENNOX the LENNOX design DAVE LENNOX the image of DAVE LENNOX and other related LENNOX marks are registered or common law trademarks of Lennox Industr...

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