Negative Pressure Switch Check - ECR International Utica Boilers UB90-50 Installation, Operation & Maintenance Manual

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 firing 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 CHECK

White Silicone Tubing
To Sight Glass Suction Port
To Gas Valve Vent
4-Way Connector
Test Line
BOILER
STATUS PRESSURE (W.C.)
Not Running
Setpoint
for Models 100 & 075
Running
Less Negative than
Without
Blockage
Running
More Negative than
With
Blockage
Models 075 and 100
Negative Pressure Switch
To Air Inlet
Vinyl Cap
Sution Port
Inclined Manometer
(Differential Pressure Gauge)
46
PRESSURE
NEGATIVE
SWITCH
CONNECTS
Normally
0"
-0.50"
Setpoint
Setpoint
Differential Air Pressure Switch
Red Transparent Vinyl Tubing
Tee
All pressure switch tubing
is clear vinyl tubing unless
otherwise noted.
P/N 240010135 Rev. D [04/15/2017]
Closed
Closed
Open