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CONNECTIONS – PLUMBING
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 required if the saturation index is greater than +0.4 (refer to
"Water Supplies"
on page 12).
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
34). A copper drain line must be fitted to the
expansion control valve (refer to
"Relief Valve Drain"
on page 35).
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.
RELIEF VALVE DRAIN
DN15 copper drain lines must be fitted to the temperature pressure relief valve and expansion control valve
(if one is installed) to carry the discharge clear of the water heater. Connect the drain lines to the valves
using disconnection unions. The drain line from the valve to the point of discharge should be as short as
possible, have a continuous fall all the way from the water heater to the discharge outlet and have no tap,
valves or other restrictions in the pipe work.
A drain line from a relief valve must comply with the requirements of AS/NZS 3500.4.
A drain line must be no longer than 9 metres with no more than three bends greater than 45° before
discharging at an outlet or air break. The maximum length of 9 metres for a drain line is reduced by 1 metre
for each additional bend required of greater than 45°, up to a maximum of three additional bends. Where the
distance to the point of final discharge exceeds this length, the drain line can discharge into a tundish.
Subject to local regulatory authority approval, the drain lines from the temperature pressure relief valve and
expansion control valve from an individual water heater may be interconnected.
The outlet of a drain line must be in such a position that flow out of the pipe can be easily seen, but arranged
so discharge will not cause injury, damage or nuisance. The termination point of a drain line must comply
with the requirements of AS/NZS 3500.4. Drain lines must not discharge into a safe tray.
In locations where water pipes are prone to freezing, drain lines must be insulated, must not exceed 300 mm
in length and are to discharge into a tundish through an air gap of between 75 mm and 150 mm.
If a drain line discharges into a tundish, the drain line from the tundish must be not less than DN20. The drain
line from a tundish must meet the same requirements as for a drain line from a relief valve.
Warning: As the function of the temperature pressure relief valve on this water heater is to discharge high
temperature water under certain conditions, it is strongly recommended the pipe work downstream of the
relief valve be capable of carrying water exceeding 93°C. Failure to observe this precaution may result in
damage to pipe work and property.
CONDENSATE DRAIN
A drain line should be fitted to the heat pump module‟s condensate drain to carry the discharge clear of the
water heater. The drain line can be extended using 12 mm rigid poly hose or conduit. The pipe work from the
condensate drain should be 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 - but arranged so water discharge will not cause
damage or nuisance.
The condensate drain line must not be connected to the relief valves drain lines but may discharge at
the same point.
35
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