Rheem 491 Owner's Manual And Installation Instructions page 15

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 "Temperature
Pressure Relief Valve" on page 16.
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 "Expansion Control
Valve" on page 15.

Check the drain line from the safe tray (if one is installed) is not blocked.
EXPANSION CONTROL VALVE
It is mandatory an expansion control valve is fitted to the cold water line to the
water heater to comply with Clause G12 of the New Zealand Building Code. 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.
Refer to "Minor Maintenance Every Six Months" on page 15. It is very important
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
your Rheem Service Centre. The expansion control valve should be checked for
performance or replaced at intervals not exceeding five (5) years, or more
frequently in areas where there is a high incidence of water deposits.
MAINTENANCE REQUIREMENTS
15