Utica Boilers UB90-200 설치 설명서

Differential air pressure switch is safety device which 

prevents boiler from firing if there is air intake, boiler heat 

exchanger or vent blockage.

Following steps and diagram indicate location of connection 

points required to measure offset pressure using inclined 

Manometer or Differential pressure gauge. Only one device 

is required to measure offset pressure.

Turn off service switch, or lower thermostat setting.

Remove vinyl caps from Tee.

Install testing lines as shown to inclined manometer or 

differential pressure gauge with ability to read 0.01” to 

at least 6.0” w.c.

Turn on service switch and set thermostat to call for 

heat.

If manometer readings do not correspond to Table 11 

check for possible causes:

•  Blockage or moisture in suction lines to switch.
•  Blockage or moisture in orifice installed in suction 

lines to switch.

•  Blockage in air intake or vent pipes.
•  Undersized air intake or vent pipes.
•  Loose blower wheel on motor shaft.
•  Incorrect pressure switch or pressure switch set-

point.

•  Gas valve out of adjustment.

When pressure reading corresponds to Table 11 

and pressure switch is operating properly, remove 

testing lines and reinstall vinyl caps to tee and 3-way 

connector.

Not Running 

0”

3.5”

Closed

0.5”

Open

Running

 Without 

Blockage 

(Approximate 

minimum vent 

lengths)

1.00” for Model 125

3.5”

0.5”

Closed

Closed

1.50” for Model 150

1.50” for Model 175

2.00” for Model 200

Running With 

Blockage

Greater Than or Equal 

To Setpoints

3.5”

Open

0.5”

Closed