Unit Start-Up - Lennox MERIT Series Installation Instructions Manual

Unit Start-Up

FOR YOUR SAFETY READ BEFORE LIGHTING
WARNING
Do not use this furnace if any part has been underwater.
A flood-damaged furnace is extremely dangerous.
Attempts to use the furnace can result in fire or explosion.
Immediately call a qualified service technician to inspect
the furnace and to replace all gas controls, control
system parts, and electrical parts that have been wet or
to replace the furnace, if deemed necessary.
WARNING
If overheating occurs or if gas supply fails to shut off,
shut off the manual gas valve to the appliance before
shutting off electrical supply..
CAUTION
Before attempting to perform any service or maintenance,
turn the electrical power to unit OFF at disconnect
switch..
BEFORE LIGHTING smell all around the appliance area
for gas. Be sure to smell next to the floor because some
gas is heavier than air and will settle on the floor.
The gas valve on the ML180UHE unit is equipped with a
gas control switch. Use only your hand to move the switch.
Never use tools. If the switch will not turn or if the control
switch will not move by hand, do not try to repair it.
Placing the furnace into operation:
ML180UHE units are equipped with an automatic igni-
tion system. Do not attempt to manually light burners on
these furnaces. Each time the thermostat calls for heat,
the burners will automatically light. The ignitor does not
get hot when there is no call for heat on units with an au-
tomatic ignition system.
WARNING
If you do not follow these instructions exactly, a fire or
explosion may result causing property damage, personal
injury or death..
Gas Valve Operation (Figure 32)
1 - STOP! Read the safety information at the beginning
of this section.
2 - Set the thermostat to the lowest setting.
3 - Turn off all electrical power to the unit.
4 - This furnace is equipped with an ignition device
which automatically lights the burners. Do not try to
light the burners by hand.
5 - Remove the upper access panel.
6 - Move switch on gas valve to OFF. Do not force. See
figure 32.
7 - Wait five minutes to clear out any gas. If you then
smell gas, STOP! Immediately call your gas supplier
from a neighbor's phone. Follow the gas supplier's
instructions. If you do not smell gas go to next step.
MANIFOLD
PRESSURE
ADJUSTMENT
SCREW
INLET
PRESSURE
PORT
GAS VALVE SHOWN IN ON POSITION
8 - Move switch on gas valve to ON. Do not force. See
figure 32.
9 - Replace the upper access panel.
10- Turn on all electrical power to to the unit.
11- Set the thermostat to desired setting.
NOTE - When unit is initially started, steps 1 through
11 may need to be repeated to purge air from gas
line.
12- If the appliance will not operate, follow the
instructions "Turning Off Gas to Unit" and call your
service technician or gas supplier.
Turning Off Gas to Unit
1 - Set the thermostat to the lowest setting.
2 - Turn off all electrical power to the unit if service is to
be performed.
3 - Remove the upper access panel.
4 - Move switch on gas valve to OFF. Do not force.
5 - Replace the upper access panel.
Failure To Operate
If the unit fails to operate, check the following:
1 - Is the thermostat calling for heat?
2 - Are access panels securely in place?
3 - Is the main disconnect switch closed?
4 - Is there a blown fuse or tripped circuit breaker?
5 - Is the filter dirty or plugged? Dirty or plugged filters
will cause the limit control to shut the unit off.
6 - Is gas turned on at the meter?
7 - Is the manual main shut-off valve open?
8 - Is the internal manual shut-off valve open?
9 - Is the unit ignition system in lock out? If the unit locks
out again, call the service technician to inspect the
unit for blockages.
10 - Is pressure switch closed? Obstructed flue will
cause unit to shut off at pressure switch. Check flue
and outlet for blockages.
Page 28
MANIFOLD
PRESSURE
OUTLET
Figure 32
PORT