39
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
LENNOX HEARTH PRODUCTS • MERIT® SERIES DIRECT-VENT GAS FIREPLACES • MODELS MLDVT-30/35/40/45 • INSTALLATION INSTRUCTIONS
Step 10. Reassemble the remaining compo-
nents by reversing the procedures outlined in
the preceding steps.
Step 11. Attach the conversion label provided
in the conversion kit to the rating plate on the
appliance.
Step 12. 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.
Step 8. 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
Step 9. (Refer to Figure 55 on Page 38 and
Figure 60)
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 60 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 are ttings).
B. Retrieve the burner and slide the venturi
tube over the orifice. Set the shutter adjust-
ing opening as shown in Figure 50, Page 32.
Figure 60
BURNER
ORIFICE
Burner Orifice Sizes
Elevation 0-4500 feet ( 0-1372 meters)
Model
Series Nat.Gas
drill size (inches) Propane
drill size (inches)
MLDVT-30 #50 (0.070")*
H4873•#59 (0.041")*
H7838•
MLDVT-35 (0.0748")*
H1355•(0.045")*
75L10•
MLDVT-40 #44 (0.086")*
60J80•#55 (0.052")*
19L52•
MLDVT-45 (0.090")*
37L70•#54 (0.055")*
99K79•
*Standard size installed at factory.
Table 9 • Part /Cat. Number.