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Unit Start-Up
FOR YOUR SAFETY READ BEFORE OPERATING
WARNING
Do not use this furnace if any part has
been underwater. A ood-damaged furnace
is extremely dangerous. Attempts to use
the furnace can result in re or explosion.
Immediately call a qualied 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
Danger of explosion. Can cause injury or
product or property damage. Should the gas
supply fail to shut o or if overheating occurs,
shut o the gas valve to the furnace before
shutting o the electrical supply.
CAUTION
Before attempting to perform any service or maintenance,
turn the electrical power to unit OFF at disconnect switch.
BEFORE LIGHTING the unit, smell all around the furnace
area for gas. Be sure to smell next to the oor because
some gas is heavier than air and will settle on the oor.
The gas valve on the ML193UHE is equipped with a gas
control switch (lever). Use only your hand to move switch.
Never use tools. If the switch will not move by hand, do
not try to repair it. Force or attempted repair may result in
a re or explosion.
Placing the furnace into operation:
ML193UHE units are equipped with an automatic hot
surface ignition system. Do not attempt to manually light
burners on this furnace. 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 these units.
Priming Condensate Trap
The condensate trap should be primed with water prior
to start-up to ensure proper condensate drainage. Either
pour 10 . oz. (300 ml) of water into the trap, or follow
these steps to prime the trap:
1 - Follow the lighting instructions to place the unit into
operation.
2 - Set the thermostat to initiate a heating demand.
3 - Allow the burners to re for approximately 3 minutes.
4 - Adjust the thermostat to deactivate the heating
demand.
5 - Wait for the combustion air inducer to stop. Set the
thermostat to initiate a heating demand and again
allow the burners to re for approximately 3 minutes.
6 - Adjust the thermostat to deactivate the heating
demand and wait for the combustion air inducer to
stop. At this point, the trap should be primed with
sucient water to ensure proper condensate drain
operation.
WARNING
. If you do not follow these instructions exactly, a re or
explosion may result causing property damage, personal
injury or death.
Gas Valve Operation (FIGURE 61)
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. See FIGURE 61.
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. See FIGURE 61
GAS VALVE SHOWN IN ON POSITION
MANIFOLD
PRESSURE
OUTLET
PORT
INLET
PRESSURE
PORT
MANIFOLD
PRESSURE
ADJUSTMENT
SCREW
FIGURE 61
9 - Replace the upper access panel.
10- Turn on all electrical power 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”
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.
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