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INSTALLATION INSTRUCTIONS & USER MANUAL
210001 V1.01 AUG 2017 - ZIP AP3/30e-100e
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Discharge arrangement
1.
Must conform to current regulations.
2. The expansion relief, temperature and pressure relief valves should drain via a tundish
which should be installed in a visible location and away from any electrical devices.
3. 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, be of metal and:
a) Be at least one pipe size larger than the nominal outlet size of the safety device unless its
total equivalent hydraulic resistance exceeds that of a straight pipe 9m long. Discharge
pipes between 9m and 18m equivalent resistance length should be at least 2 sizes larger
than the nominal outlet size of the safety device, between 18 and 27m at least 3 sizes
larger, and so on. Bends must be taken into account in calculating the flow resistance.
See diagram of typical discharge pipe arrangement and table for sizing copper discharge pipe
on page 13.
b) Have a vertical section of pipe at least 300mm long, below the tundish before any elbows
or bends in the pipework.
c) Be installed with a continuous fall.
d) Have discharges visible at both the tundish and the final point of discharge but where
this is not possible or it is practically difficult there should be clear visibility at one or other
of these locations. Examples of acceptable discharge arrangements are:
e) Ideally below a fixed grating and above the water seal in a trapped gully.
f)
Downward discharges at low level; i.e. up to 100mm 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.
g) Discharges at high level: e.g. into metal hopper and metal down-pipe with the end of the
discharge pipe clearly visible (tundish visible or not) or onto a roof capable of withstanding
high temperature discharges of water and 3m from any plastic guttering system that
would collect such discharges (tundish visible).
h) Where a single pipe serves a number of discharges, such as in blocks of flats, the number
served should be limited to not more than 6 systems so that any installation can be traced
reasonably easily. The single common discharge pipe should be at least one pipe
size larger than the largest individual discharge pipe to be connected. If unvented hot
water storage systems are installed where discharges from safety devices may not be
apparent e.g. in dwellings occupied by blind, infirm or disabled people, consideration
should be given to the installation of an electronically operated device to warn when
discharge takes place.
Note:
The discharge would consist of high temperature water and steam. Asphalt, roofing
felt and non-metallic rainwater goods may be damaged by such discharges.
Note:
It is not acceptable to discharge straight into a soil pipe. For guidance See G3 3.60.
INSTALLATION
