Lennox International Inc. GWB9-050IH-2 사용자 설명서

• Following steps and diagram indicate locations of 

connection points required to check differential air 

pressure.

• Differential air pressure switch is safety device which 

prevents boiler from fi ring if there is air intake, boiler 

heat exchanger or vent blockage.

• Turn off service switch, or lower thermostat setting.
• Remove vinyl caps from Tee and 4-way connector.
• Install testing lines as shown to inclined manometer or 

differential pressure gauge with ability to read 0.01” to 

3.0” w.c.

• Turn on service switch and set thermostat to call for 

heat.

Not Running

0”

Normally Open

Setpoint

1.00” for Model-100

1.60” for Model-75

2.10” for Model-50

Running 

Without 

Blockage

Greater Than         

Setpoints

Closed

Running 

With 

Blockage

Less Than or Equal to 

Setpoints

Open

If manometer readings do not correspond to chart above, 

check for possible causes:

• - Blockage or moisture in suction lines
• - Blockage in air intake or vent pipes
• - Undersized air intake or vent pipes
• - Loose blower wheel or motor shaft
• - Incorrect pressure switch or pressure switch setpoint

When pressure reading is proper and the pressure switch is 

operating properly, remove testing lines and reinstall vinyl 

caps to Tee and 4-way connector.