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CONNECTIONS – PLUMBING
30
BLEED VALVE DRAIN
A copper drain line must be fitted to the bleed valve to carry the discharge clear of the water heater and
solar controls. Connect the drain line to the bleed valve using a disconnection union. The pipe work
from the bleed valve to the drain should be as short as possible and fall all the way from the valve with
no restrictions. It should have no more than three right angle bends in it. Use DN15 pipe.
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 water discharge will not cause injury, damage, nuisance or
splashing. The water discharged may be of a high temperature under certain conditions. The drain line
must be fully insulated with closed cell polymer insulation or similar (minimum thickness 13 mm). The
insulation must be weatherproof and UV resistant if exposed.
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 not required unless the saturation index is greater
than +0.4 (refer to
“Water Supplies” on page 36). 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
(refer to diagrams on page 28). A copper drain line must be run
separately from the drain of the relief valve.