Watts AERCO Benchmark OMM-0121 Operation And Maintenance Manual page 51

Benchmark 750-3000 Boiler Operation & Maintenance Manual
SECTION 4 – MAINTENANCE
BMK 1500-3000 Burner Inspection Instructions
1. Set the ON/OFF switch on the C-More Controller to the OFF position. Disconnect AC
power from the unit and turn off the gas supply.
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 lead wire from the flame detector installed on the burner plate. See Figure
4-2b (BMK 1500/2000) or Figure 4-2c (BMK 2500/3000).
4. Remove the two (2) screws securing the flame detector to the plate. The flame detector is
secured to the burner plate with one (1) #10-32 screw and one (1) #8-32 screw.
5. Remove the flame detector and gasket from the burner plate.
6. Disconnect the cable from the igniter-injector.
7. Using a 7/16" open-end wrench, disconnect the compression nut securing the gas injector
tube of the igniter-injector to the elbow of the staged ignition assembly (see Figure 4-2b
(BMK 1500/2000) or Figure 4-2c (BMK 2500/3000). Disconnect the staged ignition
assembly from the igniter-injector.
8. Next, loosen and remove the igniter-injector from the burner plate using a 1" open-end
wrench.
9. Loosen and remove the four 5/16 x 1-3/4" bolts, washers, and nuts from the blower plenum
where it attaches to the blower. See Figure 4-5a & 4-5b (BMK 1500/2000) or Figure 4-5c &
4-5d (BMK 2500/3000).
10. You must either rig a support for the blower to hold it in place or remove the blower from
the unit and set it aside for later reassembly.
11. Remove the eight (8) 3/8-16 nuts, using a 9/16" wrench, attaching the blower plenum to the
burner. See Figure 4-5a & 4-5b (BMK 1500/2000) or Figure 4-5c & 4-5d (BMK 2500/3000).
12. Remove the blower plenum from between the blower and the burner and set it aside for
later reassembly. The O
plenum flange.
13. Remove the burner by pulling straight up.
NOTE:
The burner assembly weighs approximately 65 lbs. (29.5 kg).
14. Remove and replace the burner gasket(s) (see Figure 4-6, below).
IMPORTANT!
ALL THREE gaskets provided for maintenance MUST be installed during this procedure, as
shown in Figure 4-6, even if there is only one existing gasket being replaced. Note that the
LOWER RELEASE GASKET has tabs, which the others do not.
NOTE:
During reassembly, apply a light coating of high-temperature, anti-seize lubricant to the
threads of the igniter-injector and grounding screw. Also, ensure that the igniter-injector is
properly positioned as indicated in Figure 4-3b or Figure 4-3c. Torque the igniter-injector to
14 - 15 ft-lbs. (19.0 - 20.3 Nm).
OMM-0122_D • GF-206 • 5/9/2019
sensor and flame observation port remain assembled to the
2
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