Lennox Hearth MPD-33 Series, MPD-45 Series, MPD-40 Series Pilot for Honeywell Millivolt Gas Valve

b. Attach manometer to the manifold side pressure test fitting and verify manifold pres- sure reads 3.5 inches water column (0.87 kPa) for natural gas, and 10.0 inches water column (2.49 kPa) for propane gas.

c. Convert the pilot orifice as follows (see Figures 62, 63 and 64 ):

Note - Use extra care not to engage the orifice strip with the 7/16" open end wrench (contact- ing the orifice strip could cause strip distortion rendering the pilot inoperative). Also avoid wrench contact to any of the other pilot parts.

Use a 7/16" open end wrench and turn the pilot hex fitting counter-clockwise 1/4 turn. (See

Figure 62).

Note - The orifice strip tab may be randomly located on any side of the hex fitting.

d. Push the orifice strip tab all the way against

the hex fitting to align the appropriate gas type

orifice (see Figures 63 and 64). The type of

gas for which the pilot is set, is, the gas type

Pilot for Honeywell Millivolt Gas Valve

(Loosening of Hex Fitting For Orifice Strip Tab Positioning)

Hood Hood Alignment

7/16 in. Open End Wrench

	Orifice Strip Tab
	Take Care Not to Contact the Orifice Strip Tab
Figure 62	with the Hex Fitting Wrench - Distortion of the Tab
	May Render the Pilot Inoperative.
	Pilot for Honeywell Millivolt Gas Valve
	Orifice Strip Tab Position Identification
	For LP/Propane and Natural Gas

shown on the tab.

e. Retighten, clockwise, the pilot hex fitting

until the pilot hood aligns with the thermo-

couple and thermopile as indicated by the

arrows shown in Figure 62.

LP/Propane Gas Position -

1/16 in. Hole, LP and

Red Color shown on tab

L

P

Natural Gas Position -

NAT shown on tab

NAT

Figure 63	Top View of Hex Fitting and Orifice Strip Tab
	Pilot for Honeywell Millivolt Gas Valve
	Orifice Strip Tab Positioning
	Pilot Hood Position After
	Loosening Hex Fitting 1/4 Turn
	Orifice Strip Tab
	Push Tab to Set
	Gas Type Usage
	Note - Orifice Strip Tab May
	Be Randomly Located On Any
Figure 64	Side Of The Hex Fitting

NOTE: DIAGRAMS & ILLUSTRATIONS NOT TO SCALE.

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