27
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
Turn on gas supply and test for gas leaks, us-
ing a gas leak test solution (also referred to as
bubble leak solution).
Note: Using a soapy water solution is an effec-
tive leak test solution but it is not recommended,
because the soap residue that is left on the pipes/
fittings can result in corrosion over time.
A.
Light the appliance (refer to the lighting
instructions label in the control compartment
or in the Care and Operation Instructions
manual).
B.
Brush all joints and connections with the gas
leak test solution to check for leaks. If bubbles
are formed, or gas odor is detected, turn the
gas control knob (off/pilot/on) to the “OFF”
position. Either tighten or refasten the leaking
connection, then retest as described above.
C. When the gas lines are tested and leak free,
be sure to rinse off the leak testing solution.
WARNING
Never use an open flame to
check for leaks.
LENNOX HEARTH PRODUCTS • MERIT
®
SERIES DIRECT-VENT GAS FIREPLACES • MODELS MLDVT-30/35/40/45 • INSTALLATION INSTRUCTIONS
Figure 44
MILLIVOLT
Thermocouple
Hood Igniter Rod
3/8" Min
(9 mm)
Thermopile
Pilot
Nozzels
Step 7. VERIFYING APPLIANCE
OPERATION
Turn on burner then observe the individual
tongues of flame on the burner. Make sure
all ports are open and producing flame evenly
across the burner. If any ports are blocked, or
partially blocked, clean out the ports.
With gas line installed run initial system
checkout before closing up the front of the unit.
Follow the pilot lighting instructions provided
in the Care and Operation Instructions manual.
For piezo igniter location see Figure 41
on
Page 26
(millivolt appliances only).
Note: Lighting Instructions are also found on
the literature tag tied to the gas piping next
to the gas valve. To access the tag, open the
lower control compartment door (Figure 41 on
Page 26) by pulling the panel forward.
When first lighting the appliance, it will take
a few minutes for the line to purge itself of
air. Once purging is complete, the pilot and
burner will light and operate as indicated in
the instruction manual. Subsequent lighting
of the appliance will not require such purging.
Inspect the pilot flame (remove logs, if neces-
sary, handling carefully).
Millivolt Appliance Checkout
The pilot flame should be steady, not lifting
or floating. Flame should be blue in color with
traces of orange at the outer edge.
The top 3/8" (10 mm) at the pilot generator
(thermopile) and the top 1/8" minimum (tip)
of the quick drop out thermocouple should be
engulfed in the pilot flame.
Electronic Appliance Checkout
To light the burner, turn ‘ON’ the unit mounted
On/Off switch or the optional remote wall
switch. Ensure the igniter lights the pilot. The
pilot flame should engulf the flame sensor as
shown in Figure 44.
Figure 43
The flame should project 1" (25 mm) beyond
the hood at all three ports (see Figure 43).
Replace logs if removed for pilot inspection.
To light the burner; turn “ON” the remote wall
switch and rotate the gas valve control knob
counterclockwise to the “ON” position (“ON”
will be at the top side of the valve).
ELECTRONIC
Pilot
Hood
Sensor
Igniter
TEST ALL CONNECTIONS FOR GAS LEAKS
(FACTORY AND FIELD)
