Benchmark 750/1000 Boiler Installation, Operation & Maintenance Manual
CHAPTER 7 – MAINTENANCE
OMM-0082_0J
AERCO International, Inc.
•
100 Oritani Dr.
•
Blauvelt, NY 10913
Page
93
of
192
GF-130
Ph.: 800-526-0288
05/21/2014
7.4 O
2
SENSOR REPLACEMENT
The Lean Oxygen Sensor (part no. 61026) is located on the burner plate at the top of the unit
(see Figure 7-1 and
Figure 7-2
). The sensor and burner plate may be hot. Allow the unit to cool
sufficiently before removing or replacing the O
2
sensor.
O
2
Sensor Replacement
1. Set the
ON/OFF
switch on the control panel, to the
OFF
position. Disconnect AC power
from the unit.
2. Remove the top shroud from the unit by grasping the top handle and lifting straight up.
This will disengage the shroud from the four (4) pins in the side panels.
3. Disconnect the O
2
sensor lead wire by pushing in on the release tab and pulling apart the
connector.
4. Next, loosen and remove the O
2
sensor and crush washer from the burner plate using a
15/16" open-end wrench.
5. Thoroughly inspect the O
2
sensor. If eroded, the sensor should be replaced. Otherwise
clean the sensor with a fine emery cloth.
6. Reinstall the O
2
sensor and crush washer on the burner plate.
7. Reconnect the sensor lead wire.
8. Reinstall the shroud on the unit.
7.5 COMBUSTION CALIBRATION
Combustion settings must be checked at the intervals shown in Table 7-1 as part of the
maintenance requirements. Refer to Chapter 4, section 4.3 for combustion calibration
instructions.
7.6 SAFETY DEVICE TESTING
Systematic and thorough tests of the operating and safety devices should be performed to
ensure that they are operating as designed. Certain code requirements, such as ASME CSD-1,
require that these tests be performed on a scheduled basis. Test schedules must conform to
local jurisdictions. The results of the tests should be recorded in a log book. See Chapter 6-
Safety Device Testing Procedures.
7.7 BURNER ASSEMBLY INSPECTION
The burner assembly (part no. 24276) is located at the top of the unit's heat exchanger. The
burner assembly may be hot. Therefore, allow the unit to cool sufficiently before removing the
burner assembly. It should be noted that the complete burner assembly also includes the blower
and air/fuel valve assemblies for the unit.
The following parts will be required for reassembly after burner inspection:
Part No.
Description
81143
Burner Gasket
81048
Flame Detector Gasket
81064
Blower Gasket
