Rheem Water Star Owner's Manual And Installation Instructions page 23

CONNECTIONS – PLUMBING
PIPE SIZES
The pipe sizing for hot water supply systems should be carried out by persons
competent to do so, choosing the most suitable pipe size to ensure adequate
flow for each individual application. Reference to the technical specifications of
the water heater and local regulatory authority requirements must be made.
To achieve true mains pressure operation, the cold water line to the water
heater should be the same size or bigger than the hot water line from the water
heater.
The minimum recommended water supply pipe and hot pipe size is DN20 when
the Water Star is installed with a continuous flow water heater.
TEMPERATURE PRESSURE RELIEF VALVE
The temperature pressure relief valve is supplied installed in position at the top
of the water heater cylinder, underneath the jacket. The valve can be accessed
by removing the plastic cover from the top of the water heater.
A copper drain line must be fitted to the temperature pressure relief valve (refer
to "Relief Valve Drain" on page 24). The drain line connects to the underside of
the water heater.
EXPANSION CONTROL VALVE
Local regulations may make it mandatory to install an expansion control valve
(ECV) in the cold water line to the water heater. In other areas, an ECV is
"Water Supplies"
required if the saturation index is greater than +0.4 (refer to
on page 10).
The expansion control valve must always be installed after the non return valve
and be the last valve installed prior to the water heater (refer to diagram on
page 22). A copper drain line must be fitted to the expansion control valve
(refer to "Relief Valve Drain" on page 24).
The valve must be insulated with closed cell polymer insulation or similar
(minimum thickness 9 mm) and the insulation installed so as not to impede the
operation of the valve. The insulation must be weatherproof and UV resistant if
exposed.
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