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Cont...
3.3 Tundish: The Electrastream unit is supplied with a temperature & pressure relief (TPR)
valve and Pressure relief (PR) valve fitted and plumbed to the Tundish. The unit must
be positioned to allow the tundish to be visible to the occupants and away from
electrical services. The discharge pipe from the tundish should terminate in a safe place
where there is no risk to persons in the vicinity of the discharge and be made of metal.
The discharge pipe must be 22 mm copper pipe. Regulations do not permit more than
3 × 90 degree bends between the Electrastream unit and the outflow. Between the TPR
and the first 90 degree bend there must be a fall of at least 300 mm. The fall of the
pipework must be continuous and the pipe should terminate in the gully or be bent
backwards onto an outside in a place where discharge cannot be injurious to persons.
Warning: Scalding water and steam can be blown out of the discharge
pipe. Position the discharge so that it is not a hazard to property or people
(especially children).
3.4 Dishcharge pipework:
G3 Requirement
‘… there shall be precautions… to ensure that the hot water discharged from safety
devices is safely conveyed to where it is visible but will not cause danger to persons in
or about the building.’
G3 Guidance Section 3.5
The discharge pipe (D1) from the vessel up to and including the tundish is supplied by
Stuart Turner Ltd. Where otherwise the installation should include the discharge pipe(s)
(D1) from the safety device(s). In either case the tundish should be vertical, located in
the same spaces as the unvented hot water storage system and be fitted as close as
possible to, and lower than, the safety device, with no more than 600 mm of pipe
between the valve outlet and the tundish.
3.5 The discharge pipe (D2): The discharge pipe (D2) from the tundish should:
Have a vertical section of pipe at least 300 mm long below the tundish before any
elbows or bends in the pipework.
Be installed with a continuous fall of at least 1 in 200 thereafter.
The discharge pipe (D2) should be made of metal or other material that has been
demonstrated to be capable of safely withstanding temperatures of the water
discharged and is clearly and permanently marked to identify the produce and
performance standard (e.g. as specified in the relevant part of BS 7291–1:2006
Thermostatic pipes and fittings for hot and cold water for domestic purposes and
heating installations in buildings, General Requirements).
3.6 Termination of discharge pipe: The discharge pipe (D2) from the tundish should
terminate in a safe place where there is no risk to persons in the vicinity of the
discharge.
Examples of acceptable discharge arrangements are:
To a trapped gully in the end of the pipe below a fixed grating and above the water
seal.
Downward discharges at low level; i.e. up to 100 mm above external surfaces such as
car parks, hard standings, grassed areas etc. are acceptable providing that a wire cage
or similar guard is positioned to prevent contact, whilst maintaining visibility.
Discharges at high level: e.g. into a metal hopper and metal downpipe with the end of
the discharge pipe clearly visible or onto a roof capable of withstanding high
temperature discharges of water and 3 metres from any plastic guttering system that
would collect such discharges.
The discharge would consist of high temperature water and steam. Asphalt, roofing felt
and non-metallic rainwater goods may be damaged by such discharges.
