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II- PLACEMENT AND INSTALLATION
Make sure unit is installed in accordance with installation
instructions and applicable codes.
III- START-UP
A- Heating Start-Up
WARNING
Shock and burn hazard.
ML180UHE(X) units are equipped with a hot surface
ignition system. Do not attempt to light manually.
Gas Valve Operation
GAS VALVE SHOWN IN ON POSITION
MANIFOLD
PRESSURE
OUTLET
PORT
INLET
PRESSURE
PORT
MANIFOLD
PRESSURE
ADJUSTMENT
SCREW
FIGURE 19
1 - STOP! Read the safety information at the beginning
of this section.
2 - Set the thermostat to the lowest setting.
3 - Turn o 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 gas valve switch to OFF position. Do not
force. See gure 19.
7 - Wait ve 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.
8 - Move gas valve switch to ON position. Do not force.
See gure 19.
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 O Gas to Unit” and call the
gas supplier.
Turning O Gas to Unit
1 - Set the thermostat to the lowest setting.
2 - Turn o all electrical power to the unit if service is to
be performed.
3 - Remove the upper access panel.
4 - Move gas valve switch to OFF position. Do not
force. See gure 19.
5 - Replace the upper access panel.
B- Safety or Emergency Shutdown
Disconnect main power to unit. Close manual and main
gas valves.
C- Extended Period Shutdown
Turn o thermostat or set to “UNOCCUPIED” mode. Close
all gas valves (both internal and external to unit) to guar-
antee no gas leaks into combustion chamber. Turn o
power to unit. All access panels and covers must be in
place and secured.
IV-HEATING SYSTEM SERVICE CHECKS
A- C.S.A. Certication
All units are C.S.A. design certied without modications.
Refer to the ML180UHE(X) Installation Instruction.
B- Gas Piping
Gas supply piping should not allow more than 0.5”W.C.
drop in pressure between gas meter and unit. Supply gas
pipe must not be smaller than unit gas connection. Com-
pounds used on gas piping threaded joints should be re-
sistant to action of liqueed petroleum gases.
C- Testing Gas Piping
CAUTION
If a exible gas connector is required or allowed by
the authority that has jurisdiction, black iron pipe
shall be installed at the gas valve and extend outside
the furnace cabinet.
IMPORTANT
In case emergency shutdown is required, turn o the
main shut-o valve and disconnect the main power
to unit. These controls should be properly labeled
by the installer.
WARNING
Do not exceed 600 in-lbs (50 ft-lbs) torque when
attaching the gas piping to the gas valve.
When pressure testing gas lines, the gas valve must be
disconnected and isolated. Gas valves can be damaged if
subjected to more than 0.5psig (14” W.C.). See gure 20.
If the pressure is equal to or less than 0.5psig (14”W.C.),
close the manual shut-o valve before pressure testing to
isolate furnace from gas supply.
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