Utica Boilers UB90-100 インストール手順

Not Running

0”

Normally 

Closed

Setpoint

-0.50” 

for Models 100 & 075

Running 

Without 

Blockage

Less Negative than 

Setpoint

Closed

Running 

With 

Blockage

More Negative than 

Setpoint

Open

To Gas Valve Vent

Gas Valve Vent

For use on Model - 100  boilers only.

• Following steps and diagram indicate locations of 

connection points required to check negative pressure.

• Negative pressure switch is safety device which 

prevents boiler from fi ring if there is air intake 

blockage.

• Turn off service switch, or lower thermostat setting.
• Remove vinyl cap from 4-way connector.
• Install test line as shown to inclined manometer or 

differential pressure gauge with ability to read 0.01” to 

5.0” w.c.

• Turn on service switch and set thermostat to call for 

heat.

• If manometer readings do not correspond to chart, 

check for possible causes:
A.  Blockage in air intake
B.  Undersized air intake 
C.  Loose blower wheel or motor shaft
D.  Incorrect pressure switch or pressure switch 

setpoint

• When pressure reading is correct and the pressure 

switch is operating properly, remove test line and 

reinstall vinyl cap to 4-way connector.

Negative Pressure Switch

Differential Air Pressure Switch

Red Transparent Vinyl Tubing

Tee 

Vinyl Cap

All pressure switch tubing 

is clear vinyl tubing unless 

otherwise noted.

Inclined Manometer                    

(Differential Pressure Gauge)

Test Line

To Air Inlet 

Sution Port

To Sight Glass Suction Port

White Silicone Tubing

4-Way  Connector