Rheem 953060DP Owner's Manual And Installation Instructions page 52

CONNECTIONS - PLUMBING
PIPE SIZES
To achieve true mains pressure operation, the cold water line to the storage
tanks should be the same size or bigger than the hot water line from the storage
tanks.
The pipe sizing for hot water supply systems should be carried out by persons
competent to do so, choosing the most suitable pipe size for each individual
application. Reference to the technical specifications of the water heater and
local regulatory authority requirements must be made.
Refer to the table on page 44 for correct primary flow and return pipe sizing.
RELIEF VALVE
The heat pump is supplied with an integral pressure relief valve located on the
inside of the heat pump cabinet and will discharge into the tray of the heat pump.
Refer to Condensate Drain on page 53 for drainage instructions.
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 system. In other areas, an
ECV is not required unless the saturation index is greater than +0.4 (refer to
"Water Supplies" on page 21). However, an ECV may be needed in a corrosive
water area where there are sufficient quantities of silica dissolved in the water.
The expansion control valve must always be installed after the non return valve
and be the last valve installed prior to the water heater system (refer to page 47
and diagram on page 48).
EXPANSION CONTROL VALVE DRAIN
A copper drain line must be fitted to the relief valve to carry the discharge clear
of the water heater. Connect the drain line to the relief valve using a
disconnection union. The pipe work from the relief valve to the drain should be
no smaller than the outlet of the relief valve, as short as possible and fall all the
way from the water heater with no restrictions. It should have no more than three
right angle bends in it.
The outlet of the drain line must be in such a position that flow out of the pipe
can be easily seen (refer to AS/NZS 3500.4) - but arranged so hot water
discharge will not cause injury, damage or nuisance. The drain line must
discharge at an outlet or air break not more than 9 metres from the relief valve.
In locations where water pipes are prone to freezing, the drain line must be
insulated and not exceed 300 mm in length. In this instance, the drain line is to
discharge into a tundish through an air gap of between 75 mm and 150 mm.
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