Lennox Hearth MPD-40 Series Burner Adjustments Flame Appearance and sooting, Hood Installation

WARNING: HANDLE THIS GLASS WITH EXTREME CARE! THE GLASS PANEL IS SUSCEPTIBLE TO DAMAGE — DO NOT SCRATCH WHILE HANDLING OR WHILE RE-INSTALLING THE GLASS DOOR FRAME.

WARNING: NEVER OPERATE THE APPLI- ANCE WITHOUT THE FRONT GLASS EN- CLOSURE PANEL IN PLACE AND SECURE.

Step 10. BURNER ADJUSTMENTS

Flame Appearance and sooting

Proper flame appearance is a matter of taste. Gen- erally, most people prefer the warm glow of a yellow to orange flame. Appliances operated with air shut- teropeningsthataretoolargewillexhibitflamesthat are blue and transparent. These weak, blue and transparent flames are termed anemic. If the air shutter opening is too small sooting may develop.

Sooting is indicated by black puffs developing at the tips of very long orange flames. Sooting results in black deposits forming on the logs, appliance inside surfaces and on exterior surfaces adjacent to the vent termination. Sooting is caused by incomplete combustion in the flames and lack of combustion air entering the air shutter opening. To achieve a warm yellow to orange flame with an orange body that does not soot, the shutter open- ing must be adjusted between these two extremes.

No smoke or soot should be present. Reposi- tion the logs if flames impinge on any of them. If the logs are properly positioned and sooting conditions exist, the air shutter opening on the main burner tube should be adjusted. Normally, the more offsets in the vent system, the greater the need for the air shutter to be opened further.

WARNING: AIR SHUTTER ADJUSTMENT SHOULD ONLY BE PERFORMED BY A QUALIFIED PROFESSIONAL SERVICE TECHNICIAN.

IMPORTANT: ENSURE THAT THE FRONT GLASS PANEL IS IN PLACE AND SEALED DURING ADJUSTMENT.

Burner Adjustment

CAUTION: THE ADJUSTMENT ROD AND NEARBY APPLIANCE SURFACES ARE HOT. EXERCISE CAUTION TO AVOID INJURY WHILE ADJUSTING FLAME APPEARANCE.

To adjust the flame, move the adjustment rod (located in the lower control area) up or down to increase or reduce the air shutter opening, respectively. Initially, always position the air shutter to the factory setting (the minimum air opening position) as shown in Figure 54.

This can be done by pulling the adjustment rod all the way down. Allow the burner to operate for at least 15 minutes. Observe the flame continuously. If it appears weak or sooty as previously described, adjust the air shutter by pushing or pulling on the adjustment rod until the flame appearance is as desired.

	Adjusting Set Screw
		Adjustment Rod Up
		(Fully Open Position)
Burner Tube
Air Shutter
Adjustment Rod Down
(minimum air
opening position)
		FACTORY AIR
Models	Gas	SHUTTER
	Type	SETTING
		inches (mm)
MPDT-3328	Nat.	1/32 (O.8)
	Prop.	3/16 (4.76)
MPDR-3328	Nat.	1/32 (O.8)
	Prop.	3/16 (4.76)
MPD-3530	Nat.	1/32 (O.8)
	Prop.	3/16 (4.76)
MPD-4035	Nat.	1/8 (3.2)
	Prop.	1/2 (13)
MPD-4540	Nat.	1/8 (3.2)
	Prop.	1/2 (13)

Figure 54

The adjustment rod and associated adjustable air shutter is patented technology. Flame ad- justments can be made quickly and accurately to taste without the need of disassembling the appliance and waiting for 30 minutes after each adjustment.

Note: If the flame still appears anemic with the air shutter closed all the way against the stop (usually a result of lengthy vertical runs), turn the appliance off, turn the gas supply off, wait for the parts to cool, remove the glass door and logs to access the air shutter. The shutter is prevented from actually closing all the way by an adjustment set screw (see Figure 54). Remove this screw using a 1/4 inch nut driver. Reinstall the logs and glass door, turn the gas back on and then restart the appliance. After 30 minutes, reobserve the flame. Adjust the air shutter as previously described.

When satisfied that the appliance operates properly, proceed to finish the installation. Leave the control knob in the ON position and the remote switch OFF. Close the lower control compartment door.

Step 11. HOOD INSTALLATION

All of these appliances must have hoods installed prior to operating.

On all clean face units, slide the hood into the slots on the lower edge of the radiant panel

(Figure 55 ).

On louvered face units, slide the hood into the slots on the lower edge of the cabinet top

(Figure 56 ).

FINISHING REQUIREMENTS

Wall Details

Complete finished interior wall. To install the appliance facing flush with the finished wall, position framework to accommodate the thick- ness of the finished wall (see Figure 55, and

Figure 56 ).

NOTE: DIAGRAMS & ILLUSTRATIONS NOT TO SCALE.

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