Lennox Hearth Figure 55 Millivolt Appliances, Figure 56, Figure 59, Figure 57, Figure 58, Figure 60, Table 9

39
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
Figure 55
Millivolt Appliances
Step 5. SIT Systems - Refer to Figure 56 and
the instructions provided with the kit. Using
a Torx T20 (with 1/4" shank and center hole),
remove and discard the three pressure regulator
mounting screws. Remove the pressure regu-
lator, 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 Tighten screws to 25 In.
lb. torque.
Electronic Appliances
Step 7. Dexen Electronic Valves - See Figure
58 and the instructions provided with the kit.
Remove and discard the two pressure regula-
tor mounting screws. Remove the pressure
regulator and diaphragm. Discard all removed
components. Ensure the provided diaphragm
is installed properly onto the replacement
pressure regulator and install the new pres-
sure regulator using the new screws supplied
with the kit. Tighten screws.
Step 5. Attach manometer to the manifold side
pressure test fitting and verify manifold 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.
Step 6. See Figure 57 and remove the pilot
hood assembly to access the hexed pilot orifice.
Remove and replace the orifice with the one
provided with the kit.
Figure 56
Figure 57
Pressure
Regulator
Remove
These
Components
Pilot
Orifice
Figure 58 - Dexen Electronic Gas Valve
Supply Gas
Inlet
Pressure-Tap
(Manifold)
Regulator
Mounting
Screw
Burner Stage
Terminal Gas
Outlet
To Burner
Ground (TP)
Pilot Stage
Terminal
Pilot Gas Outlet
Pressure-Tap
(Inlet)
PILOT
OUT
VENT
LO
TH TP
TH
TP
HI
IN
IN
Note: If the igniter is damaged, a replace-
ment kit is available, order Catalog Number
87L54.
Step 10. Attach the conversion label provided
in the conversion kit next to the rating plate on
the appliance.
Step 11. Turn on gas supply and test for gas
leaks (refer to page 26).
Always test pressure with the valve regulator
control at the highest setting.
See Figure 59 and replace the pilot orifice as
follows: Remove pilot hood assembly to access
the phillipped pilot orifice. Remove and replace
the orifice with the one provided with the kit.
Exercise extreme care to prevent damage to
or breakage of the igniter assembly.
All Models
Note: Use pipe joint compound or Teflon tape
on all pipe fittings before installing (ensure
propane resistant compounds are used in
propane applications, do not use pipe joint
compounds on flare fittings).
Step 8. (Refer to Figure 55)
A. Remove the orifice from the manifold and
replace it with the one provided in the kit. See
Table 9 for orifice sizes for natural and pro-
pane models. Figure 60 illustrates the orifice.
Always check and verify orifice size.
B. Retrieve the burner and slide the venturi
tube over the orifice. Set the shutter adjusting
opening as shown in Figure 53, Page 34.
Step 9. Reassemble the remaining components
by reversing the procedures outlined in the
preceding steps.
Figure 59
Figure 60
ELECTRONIC
Pilot
Hood
Sensor
Igniter
Burner Orifice Sizes
Elevation 0-4500 feet ( 0-1372 meters)
Model
Series Nat.Gas drill size (inches) Propane drill size (inches)
ELDV35 #38 (0.1015")*
99K76•
#53 (0.0595")*
39L10•
ELDV40 #37 (0.1040")*
24M10•
(0.062")*
21L01•
ELDV45 #36 (0.1065")*
74L88•
#52 (0.0635")*
80L41•
Table 9 * Standard size installed at factory
• Part /Cat. Number
Burner Assembly
Gas Valve
Assembly
Orifice