Loading ...
Loading ...
Loading ...
The following steps and diagram
indicate the locations of the con-
nection points required to check
the differential air pressure.
The differential air pressure swi-
tch 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 ther-
mostat to call for heat.
C.
Boiler Status Differential Pressure (w.c.)
Not Running 0"
Setpoint
Pressure Switch Connects
Normally Open
1.17" for Q90-100
1.35" for Q90-75
1.55" for Q90-50
Running Without Greater Than Setpoints Closed
Blockage
Running With Less Than or Equal to Open
Blockage Setpoints
If manometer readings do not correspond to the chart above, check for possible causes:
- Blockage or moisture 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 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.
58
Loading ...
Loading ...
Loading ...