Step 7. Checking Unit Operation - Lennox MLDVT-30NM Installation Instructions Manual

Length Of Pipe With
Attached Shut-Off Valve
Figure 39
Refer to Figure 39 and insert the last length of
gas pipe with its attached shut-off valve into the
lower control compartment, and pass it through
the gas line access hole on the left side of the
appliance outer wrapper. Using appropriate
materials for the gas type, thread the last length
of pipe into the end of the gas vent run and
tighten in place using a pipe wrench external
to the appliance between the appliance outer
wrapper and the framing.
Important: Turn the last piece of gas pipe in
the last fitting until the shut-off valve is posi-
tioned in a way that allows the shut-off valve
handle to be accessed in the lower control
compartment, easily operated throughout its
full range of motion.
Bring the flex line to the shutoff valve by hand
and align the flare fittings. Tighten the fittings
by hand, and then use wrench to tighten com-
pletely, 1/4 turn at a time.
Test All Connections For Gas Leaks (Factory
And Field)
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 (50%
dish soap, 50% water) is an effective 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. Never use
an open flame to check for leaks.
A. Light the appliance (refer to the lighting
instructions label in the control compartment
or in the Care and Operation Instructions).
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 to the "OFF" position. Either
tighten or refasten the leaking connection and
retest as described above.
C. When the gas lines are tested and leak free,
be sure to rinse off the leak testing solution.
D. 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.
Step 7. CHECKING APPLIANCE
OPERATION
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. For
piezo igniter location see Figure 38 on page
24 (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 38 on page
24 ) 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 instruc-
tion manual.
Subsequent lighting of the appliance will not
require such purging. Inspect the pilot flame (re-
move logs, if necessary, 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" min (tip) of the
quick drop out thermocouple should be engulfed
in the pilot flame.
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
The flame should project 1" (25 mm) beyond the
hood at all three ports (Figure 40). 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).
Hood Igniter Rod
MILLIVOLT
Thermocouple
Pilot
Nozzels
Thermopile
Figure 40
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 rod as shown
in Figure 41.
ELECTRONIC
Sensor
Igniter
Figure 41
3/8" Min
(9 mm)
Pilot
Hood
25