Differential Air Pressure Switch Check - UTICA BOILERS UB90-50 Installation Manual

What Is System Status?
The following steps and diagram
indicate the locations of the
connection points required
to check the differential air
pressure.
The differential air pressure
switch is a safety device which
will prevent the boiler from
firing if there is an 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
the ability to read 0.01" to 2.0"
w.c.
Turn on service switch and set
thermostat to call for heat.
Boiler statUs
Not Running
Setpoint
Running Without Blockage
Running With Blockage
If manometer readings do not correspond to the 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
- Inncorect 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.

DIFFERENTIAL AIR PRESSURE SWITCH CHECK

DiFFereNtial PressUre (w.c.)
0"
1.00" for Model-100
1.35" for Model-75
1.55" for Model-50
Greater Than Setpoints
Less Than or Equal to Setpoints
PressUre switcH coNNects
62
Normally Open
Closed
Open