Benchmark Platinum-Edge: Operation-Service Manual
SECTION 8 – MAINTENANCE
OMM-0137_D • GF-211
•
7/16/2019
Technical Support
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(800) 526-0288
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8.10.1 Rear Refractory Replacement
Rear Refractory Replacement Instructions
1. Turn off gas and electrical power to the unit. In addition, turn off any other units sharing the
exhaust flue.
2. Disconnect the flue from the exhaust manifold of the boiler being serviced and remove flue
sections up to the top of the unit enclosure.
3. Remove the small O
2
Sensor Cover from the rear sheet metal enclosure panel. The Air
Eductor assembly is clipped to the bottom edge of this opening. Lift the Air Eductor
assembly up off the left-rear panel, then secure it in place with a length of cord or wire.
DO
NOT REMOVE THE LEFT-REAR PANEL
without first securing the Air Eductor assembly
in place.
NOTE:
At the top, the left and right-rear panels are attached to the left and right top rails by nuts. At
the bottom, each rear panel is attached to the base with one nut each. Access the nuts for
removal through the side panel, as shown in Figure 8-8.
4. Remove the left-rear panel, which is held in place by 2 spring latches and 7/16” bolts,
inside the panel on the top rail and bottom lip. See Figure 8-8, below.
5. With the panels removed, the rear plate of the combustion chamber can be accessed, as
shown in Figure 8-9, below.
CAUTION!
The surfaces of the heat exchanger may be hot. Allow the unit to cool sufficiently before
proceeding to the next step.
6. Remove the O
2
sensor and the 1/4” stainless steel tube from the rear plate.
7. Disconnect the wires from the thermal switch on the rear plate.
8. Remove all of the nuts from the rear plate, EXCEPT for the one at the top of the plate.
9. Loosen (but DO NOT REMOVE) the top nut and slide a thin metal object (such as a
hacksaw blade) between the rear plate and the fiber material of the rear refractory to
separate the material from the plate.
CAUTION!
The rear plate weighs approximately 40 pounds. It is therefore recommended that 2 people
remove the plate.
10. Remove the top nut from the plate and remove it from the unit.
11. Optionally, you can thread 2 small nipples into the rear plate to act as handles, which will
ease removal and reinstallation.
