Rheem Light Duty Commercial Electric Water Heater Use And Care Manual page 11

The following instructions are intended for qualified
service personnel ONLY, and should only be done
Cavity Insert Instructions
when necessary.
11
In order to replace the thermostat or heating element,
remove the cavity insert crossbar by following the
instructions below:
1. Turn off the power to the water heater.
2. Remove the jacket access panel(s) and insulation.
3. Rotate the crossbar up and down until it breaks
away from the remainder of the cavity insert.
(See illustration to the left)
Discard the crossbar. It cannot and need not be
replaced.
4. Replace the thermostat and/or element as
necessary.
5. Replace the insulation and jacket access panel(s)
before turning on the power to the water heater.
NOTICE: The cavity insert crossbar is necessary for
the manufacturing process only. The removal of
the crossbar will not interfere with the operation of
the water heater.