Lennox International Inc Merit Series Gas Furnace installation instructions Unit Start−Up

Unit Start−Up

FOR YOUR SAFETY READ BEFORE LIGHTING

WARNING

Do not use this furnace if any part has been under- water. A flood−damaged furnace is extremely dan- gerous. Attempts to use the furnace can result in fire or explosion. Immediately call a qualified ser- vice 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 mainte- nance, turn the electrical power to unit OFF at dis- connect 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 ML180UH unit will be 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:

ML180UH units are equipped with an automatic ignition 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 automatic 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 35)

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 35.

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.

MANIFOLD		MANIFOLD
PRESSURE
		PRESSURE
ADJUSTMENT
		OUTLET
SCREW
		PORT
INLET
PRESSURE
PORT	GAS VALVE SHOWN IN ON POSITION

FIGURE 35

8 − Move switch on gas valve to ON. Do not force. See fig- ure 35.

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 urning Off Gas to Unit" and call your service techni- cian 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.

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