Aerco Benchmark BMK 750 User Manual page 46

Benchmark 750-3000 Boiler Operation, Service, Maintenance Guide - KOREA
SECTION 4 – MAINTENANCE
BMK 750/1000 Burner Inspection Instructions
9. Disconnect the unit wiring harness connectors from the air/fuel valve and blower motor.
10. Disconnect the wire leads connected to the Blower Proof switch and Blocked Inlet switch
(Figure 4-4a and Figure 4-4b).
11. Disconnect the gas train from the air/fuel valve by removing the four (4) 1/2" bolts and nuts
(Figure 4-4a).
12. Disconnect the flex hose from the air/fuel valve by loosening the hose clamp.
13. Remove the four 5/16-18 hex head screws securing the blower to the burner plate (Figure
4-4b).
14. Remove the blower and air/fuel valve from the burner plate by lifting straight up. Also,
remove the blower gasket.
15. Remove the eight (8) 3/8-16 nuts from the burner flange (Figure 4-4a) using a 9/16"
wrench.
NOTE:
The burner assembly weighs approximately 25 pounds (11.3 kg).
16. Remove the burner assembly from burner flange by pulling straight up.
17. Remove and replace the burner gasket.
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 4-3a. Torque the igniter-injector to 14 - 15 ft-lbs.
(19.0 - 20.3 Nm).
18. Beginning with the burner assembly removed in step 16, reinstall all the components in the
reverse order that they were removed. When reinstalling the burner flange (removed in
step 15), tighten the 3/8-16 nuts using a typical torque pattern. For example, loosely tighten
one nut, then loosely tighten a second nut on the opposite side, a third at 90 degrees to the
first two, and a fourth opposite the third, and then repeat this pattern with the remaining
four nuts. Repeat the entire pattern a second time to partially tighten all eight nuts, and
then repeat a third time until all eight nuts are fully torqued to 30 ft. lbs. (40.7 Nm).
19. Ensure that the igniter-injector and flame detector cutouts in the burner plate are properly
aligned with the heat exchanger top flange.
This completes the Benchmark 750/1000 burner inspection.
Page 46 of 146
11/29/2017
AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913
Ph.: 800-526-0288
OMM-0128_0C
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