Lennox Hearth MPD35ST-PM Model, Propane, Millivolt Appliance Checkout, Electronic Pilot Assembly

2.Light appliance (follow lighting procedure on lighting label in control compartment or see homeowners manual).

3.Allow the burner to operate for at least 15 min- utes while observing the flame continuously to ensure that the proper flame appearance has been achieved (see Figure 13 ). If the following conditions are present, adjust accordingly.

•If flame appears weak or sooty, adjust the air shutter, incrementally, to a more open position until the proper flame appearance is achieved.

•If flame stays lowered blue, adjust the air shutter, incrementally, to a more closed position until the proper flame appearance is achieved.

4.Leave the control knob (off/pilot/on) in the ON position and the burner OFF/ON switch OFF (& remote switches, if applicable).

5.When satisfied that the burner flame appear- ance is normal, close the lower control compartment door.

Decrease Shutter Opening		Note - Burners are
In This Direction
		omitted in this
		view for clarity.
	Orifice
Air Shutter
Adjusting	Increase Shutter	Opening
Rod	In This Direction
Main Burner Factory Air Shutter
Opening Setting - All Models
Model	Natural	Propane
	Gas	Gas
MPD35ST	1/8”	1/4”
	3.2mm	6.4mm
Figure 14	Adjustment Rod Positions
	(when viewed from above)

Millivolt Appliance Checkout

The pilot flame should be steady, not lifting or floating. Flame should be blue in color with traces of orange at the outer edge.

The top 3/8" (10 mm) at the pilot generator (thermopile) and the top 1/8" minimum (tip) of the quick drop out thermocouple should be engulfed in the pilot flame. The flame should project 1" (25 mm) beyond the hood at all three ports. See Figure 15.

To light the burner, refer to the lighting instruc- tions on Page 15.

MILLIVOLT PILOT ASSEMBLY
Proper Pilot Flame Appearance
Hood	Igniter Rod
Thermocouple	3/8" Min.
	(9 mm)
Pilot
Nozzels
Thermopile
Figure 15

Electronic Appliance Checkout

To light the burner, refer to the lighting instruc- tions on Page 16. Ensure the igniter lights the pilot. The pilot flame should engulf the flame sensor as shown in Figure 16.

ELECTRONIC PILOT ASSEMBLY
Proper Pilot Flame Appearance
Proper Flame	3/8" to 1/2"
	(9 -13 mm)
Adjustment
Pilot
Nozzels	Ground
	Electrode
	Flame Rod
	Hot Surface
	Igniter
Figure 16

With proper care and maintenance, your appli- ance will provide many years of enjoyment. If you should experience any problem, first refer to the troubleshooting guide in this manual. If problem persists, contact your Lennox distributor.

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NOTE: DIAGRAMS & ILLUSTRATIONS NOT TO SCALE.