Rheem Stellar 50L Owner's Manual And Installation Instructions page 11

MINOR MAINTENANCE EVERY SIX MONTHS
It is recommended minor maintenance be performed every six (6) months. Minor
maintenance can be performed by the dwelling occupant.
The minor maintenance includes:

Operate the easing lever on the temperature pressure relief valve. It is very
important you raise and lower the lever gently. Refer to
Pressure Relief Valve"
Warning: Exercise care to avoid any splashing of water, as water
discharged from the drain line will be hot. Stand clear of the drain line's point
of discharge when operating the valve's lever.

Operate the easing lever on the expansion control valve (if fitted). It is very
important you raise and lower the lever gently. Refer to
Valve" on page 11.

Check the drain line from the safe tray (if one is installed) is not blocked.
EXPANSION CONTROL VALVE
In many areas, including South Australia, Western Australia and scaling water
areas, it is mandatory an expansion control valve is fitted to the cold water line
to the water heater. The expansion control valve may discharge a small quantity
of water from its drain line during the heating period instead of the temperature
pressure relief valve on the water heater.
Operate the easing lever on the expansion control valve once every six months.
"Minor Maintenance Every Six Months"
Refer to
the lever is raised and lowered gently. If water does not flow freely from the
drain line when the lever is lifted, then the water heater should be checked by
Rheem Service or their nearest Accredited Service Agent. The expansion control
valve should be checked for performance or replaced at intervals not exceeding
5 years, or more frequently in areas where there is a high incidence of water
deposits.
on page 12.
11
MAINTENANCE REQUIREMENTS
"Expansion Control
on page 11. It is very important
"Temperature