Page 4
Start-Up & Operation Information
WARNING
If you do not follow these instructions exactly, a fire
or explosion may result causing property damage,
personal injury or death.
BEFORE PLACING THE UNIT INTO OPERATION,
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 ML180UH will be equipped with a gas
control switch. Use only your hand to move the switch. Nev
er use tools. If the switch will not move by hand, do not try to
repair it. Call a licensed professional service technician (or
equivalent). Force or attempted repair may result in a fire or
explosion.
Placing the ML180UH furnace into operation:
ML180UH units are equipped with an ignition system. Do
not attempt to manually light burners on this furnace. Each
time the thermostat calls for heat, the burners will automati
cally light. The ignitor does not get hot when there is no call
for heat on units with this ignition system.
Operating the Gas Valve (Figure 2)
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
. See figure 2.
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 instruc
tions. If you do not smell gas go to next step.
8 - Move switch on gas valve to
ON
. See figure 2.
FIGURE 2
GAS VALVE SHOWN IN ON POSITION
MANIFOLD
PRESSURE
OUTLET
PORT
INLET
PRESSURE
PORT
MANIFOLD
PRESSURE
ADJUSTMENT
SCREW
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 section
“Turning Off Gas to the Unit” and call your licensed pro
fessional service technician (or equivalent).
Turning Off Gas to the Unit
WARNING
If overheating occurs or if gas supply fails to shut off,
shut off the manual gas valve to the furnace before
shutting off electrical supply.
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
OFF
.
5 - Replace the upper access panel.
WARNING
Do not set thermostat below 60°F (16°C) in heating
mode. Setting thermostat below 60°F (16°C) reduces
the number of heating cycles. Damage to the unit
may occur that is not covered by the warranty.
Filters
All ML180UH filters are installed external to the unit. Filters
should be inspected monthly. Clean or replace the filters
when necessary to ensure proper furnace operation. Re
placement filters must be rated for high velocity airflow.
Table 1 lists recommended filter sizes.
A filter must be in place when the unit is operating.
TABLE 1
Furnace
Cabinet Width
Filter Size
Side Return
Bottom Return
14-1/2”
16 X 25 X 1 (1)
14 X 25 X 1 (1)
17-1/2”
16 X 25 X 1 (1)
16 X 25 X 1 (1)
21”
16 X 25 X 1 (1)
20 X 25 X 1 (1)
24-1/2”
16 X 25 X 1 (2)
24 X 25 X 1 (1)
Maintenance
A licensed professional service technician (or equivalent)
should inspect the complete system each season (heating
and cooling). The following maintenance procedures
should only be conducted by a licensed professional ser
vice technician (or equivalent).
Do not attempt to service
the unit in any way.
