Specifications

CONNECTIONS – PLUMBING

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.