Lennox Hearth Products MLDVTCD-35NE Installation Instructions Manual page 37

LENNOX HEARTH PRODUCTS • MERIT
Millivolt Appliances
Step 5. SIT Systems - Refer to Figure 50 on
Page 37 and the instructions provided with
the kit. Using a Torx T20 (with 1/4" shank and
center hole), tool or standard flat screwdriver
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 and install the new pressure regula-
tor using the new screws supplied with the kit.
Tighten screws to 25 In. lb. torque.
Pressure
Regulator
Remove
These
Components
Figure 50
Step 6. See Figure 51 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 51
SERIES DIRECT-VENT CONTEMPORARY DESIGN GAS FIREPLACES • MODEL MLDVTCD-35 • INSTALLATION INSTRUCTIONS
®
Electronic Appliances
Step 7. Dexen Electronic Valves - See Figure
52 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.
See Figure 53 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.
Pressure-Tap
(Manifold)
Supply Gas
Inlet
PILOT
Pilot Gas Outlet
Figure 52
- Dexen Electronic Gas Valve
ELECTRONIC
Sensor
Igniter
Note: If the igniter is damaged, a re-
placement kit is available, order Catalog
Number 87L54.
Figure 53
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
Burner Stage
Terminal
Regulator Gas
Mounting Outlet
Screw To Burner
LO
HI
Pressure-Tap
Pilot Stage
(Inlet)
Terminal
Ground (TP)
Pilot
Hood
All Models
Step 8. (Refer to Figure 49 on Page 36 and
Figure 54)
VERIFY THE PROPER ORIFICE SIZE
BEFORE INSTALLING IT.
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 54 illustrates the orifice.
Use pipe joint compound or Teflon tape on all
pipe fittings before installing (ensure propane
resistant compounds are used in propane ap-
plications, do not use pipe joint compounds
on flare fittings).
B. Retrieve the burner and slide the venturi
tube over the orifice. Set the shutter adjusting
opening as shown in Figure 49 on Page 36.
Burner Orifice Sizes
Elevation 0-4500 feet ( 0-1372 meters)
Model Nat.Gas
Series drill size (inches)
#49 (0.073") *
MLDVTCD-35
21L82 •
* Standard size installed at factory
** Standard size in LP conversion kit
Table 9
• Part /Cat. Number
Figure 54
Step 9. Reassemble the remaining components
by reversing the procedures outlined in the
preceding steps.
Step 10. Attach the conversion label provided
in the conversion kit to the rating plate on the
appliance.
Step 11. Turn on gas supply and test for gas
leaks. See Test All Connections For Gas Leaks
on Page 27.
Step 12. 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.
ALWAYS TEST PRESSURES WITH THE VALVE
REGULATOR CONTROL AT THE HIGHEST
SETTING.
Propane
drill size (inches)
(0.045") **
75L10 •
37