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Figure 40
b. Attach manometer to the manifold side
pressure test fi tting 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. Refer to Figure 40 and remove the pilot hood
assembly to access the hexed pilot orifi ce.
Remove and replace the orifi ce with the one
provided with the kit.
Pilot for SIT Millivolt
Gas Valve
Pilot
Orifi ce
Figure 42
All Models
Step 6. Remove the orifi ce from the manifold
and replace it with the one provided with the
kit. See Table 7 for orifi ce sizes for natural
and propane models. Figure 43 illustrates the
orifi ce.
Figure 41
Step 5. Electronic Appliances -
Honeywell Systems
See Figure 41 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 units. Silver cap and
stainless steel spring for natural gas units.
Before installing the cap, attach manometer
to the manifold side pressure test fi tting 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 42 and replace the pilot orifi ce as fol-
lows: Remove the igniter assembly retainer clip,
and carefully remove the igniter assembly.
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 fl are nut at
the end of the pilot gas line to free the pilot
assembly from the gas line. Remove the pilot
orifi ce 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 re-
placement kit is available - order Catalog
Number 87L54.
Pilot Assembly
Igniter Assembly
Retaining Clip
Pilot Orifi ce
Flare Nut
Spring
Adjusting
Screw
Slotted
Cap
PS
I
OFF
I
ON
CONTROL
IG
N
IT
E
Manifold
Pressure
Test Port
Inlet Pressure Test Port
Figure 43
Step 7. Reassemble all removed components
by reversing the procedures outlined in the
preceding steps. Use pipe joint compound or
Tefl on tape on all pipe fi ttings before installing
(ensure propane resistant compounds are used
in propane applications, do not use pipe joint
compounds on fl are fi ttings).
Step 9. Attach the conversion label provided
in the conversion kit to the rating plate on the
appliance.
Step 10. Turn on gas supply and test for gas
leaks.
Burner Orifi ce Sizes
Elevation 0-4500 feet ( 0-1372 meters)
Models
Natural
Gas
drill size (inches)
Propane
Gas
drill size (inches)
MPB-3328 #47 (.0785") #1.2mm (.048")
MPB-3530 #44 (.086") #55 (.052")
MPB-4035 #37 (.104") 1/16"
(.0625")
MPB-4540 #36 (.1065") #52
(.0635")
Table 7
The manufacturer reserves the right to make changes at any time, without notice, in design,
materials, specifi cations, prices and also to discontinue colors, styles and products.
Consult your local distributor for fi replace code information.
Printed in U.S.A. © 2005 by LENNOX HEARTH PRODUCTS
P/N 850,033M REV. B 05/2006
NOTE: DIAGRAMS & ILLUSTRATIONS NOT TO SCALE.
1110 West Taft Avenue • Orange, CA 92865
Pilot Hood