Rheem 491 Owner's Manual And Installation Instructions page 16

MAINTENANCE REQUIREMENTS
TEMPERATURE PRESSURE RELIEF VALVE
This valve is near the top of the water heater
and is essential for its safe operation. It is
possible for the valve to release a little water
through the drain line during each heating
period. This occurs as the water is heated
and expands by approximately 1/50 of its
volume.
Continuous leakage of water from the valve
and its drain line may indicate a problem
with the water heater (refer to "Temperature
Pressure Relief
page 22).
Warning: Never block the outlet of this
valve or its drain line for any reason.
Operate the easing lever on the temperature
pressure relief valve once every six (6)
months. Refer to "Minor Maintenance Every
Six Months" on page 15. It is very
important the lever is raised and lowered
gently.
DANGER: Failure to do this may result
in the water heater cylinder failing, or under
certain circumstances, exploding.
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.
If water does not flow freely from the drain line when the lever is lifted, then the
water heater must be checked. Phone your Rheem Service Centre to arrange
for an inspection.
The temperature pressure relief valve should be replaced at intervals not
exceeding five (5) years, or more frequently in areas where there is a high
incidence of water deposits (refer to "Water Supplies" on page 17).
Valve Running"
on
lift until water
flows from the
drain line –
lower gently
16
water
heater
drain
line