Lennox MPD35ST-NM-B Installation Instructions Manual page 37

Air Shutter
Adjustment Lever
Valve Access Side
of Fireplace
Figure 64
c. Locate the two (2) latches at the top of
the control compartment. To disengage
the two latches from the bottom vee-
flange of the glass enclosure panel,
reach for the handles located towards
the back of the latches and pull the
handles down toward the front of the
appliance.
d. Swing the bottom of the door out and
raise it slightly to lift the top flange of
the door frame away from the appli-
ance.
Step 2. Carefully remove the log set. Exercise
care as not to break the log set.
Step 3. Referring to Figure 64, remove the
burner.
Millivolt Appliances
Step 4. Refer to Figure 65 and the instructions
provided with the kit. Using a Torx
T20 tool or standard flat screwdriver,
remove and discard the three pressure
regulator mounting screws. Remove
the pressure regulator, spring, poppet,
diaphragm and bushing. Discard all
removed components. Ensure the
rubber gasket installed on the back of
the replacement pressure regulator is
properly positioned and install the new
pressure regulator using the new screws
supplied with the kit. Tighten screws to
25 In. lb. torque.
Pressure
Regulator
Remove
These
Components
Figure 65
Firebox Subfloor
Step 5. 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.
Step 6. Refer to Figure 66 and remove the
pilot hood assembly to access the hexed pilot
orifice. Remove and replace the orifice with
the one provided with the kit.
Pilot
Orifice
Figure 66
Electronic Appliances
Step 7. Honeywell Electronic Valves - See
Figure 67 and the instructions provided with
the kit. Remove the slotted cap screw, o-ring,
pressure-regulating adjusting screw and spring.
Retain all parts for possible later use. Install
new components from the kit. Black cap and
red spring for propane gas appliances. Silver
cap and stainless steel spring for natural gas
appliances. Before installing the cap, attach
manometer to the manifold side pressure test
fitting and adjust screw until pressure reads
3.5 inches water column (0.87 kPa) for natural
gas, and 10.0 inches water column (2.49 kPa)
for propane gas.
See Figure 68 and replace the pilot orifice as fol-
lows: Remove the igniter assembly retainer clip,
and carefully remove the igniter assembly.
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
Pan Burner
Venturi Tube
Arm
Exercise extreme care to prevent damage to
or breakage of the igniter assembly.
Remove the screw securing the pilot assembly
to its mounting bracket. Back off the flare nut
at the end of the pilot gas line to free the pilot
assembly from the gas line. Remove the pilot
orifice and replace it with the one provided with
the conversion kit. Reinstall the pilot assembly
by reversing the steps detailed here.
When reinstalling the igniter assembly, use
extreme care to prevent damage and break-
age. Do not apply any leverage to the igniter
assembly while restoring the retainer clip to
its original position.
Note: If the igniter is damaged, a replacement kit
is available, order Catalog No. 87L54.
Figure 68
All Models
Step 8. (Refer to Figure 64 )
a. Remove the orifice from the manifold and
replace it with the one provided in the kit.
The following Table shows the orifice sizes
for natural and propane models. Figure 69
illustrates the orifice.
Gas Valve
Assembly
Manifold
Pressure
Test Port
Slotted
Cap
Spring
Adjusting
Screw
Figure 67
Pilot
Orifice
Igniter
Assembly
Retaining
Flare Nut
Clip
Pilot
Assembly
37