Glow-worm Ultrapower sxi - Manual (Page 16)

16
5 Domestic Hot Water
5.6 SYSTEM REQUIREMENTS – Domestic Hot
Water
Domestic Hot Water Requirements
General - All domestic hot water circuits, connections, fittings
must be in accordance with the relevant standards and water
supply regulations.
For GB: Guidance G17 to G24 and recommendation R17 to
R24 of the Water Regulations Guide (for Scotland, the Water
Byelaws 2000, Scotland) .
Document G Sanitation, hot water safety and water efficiency,
section 3 of the building regulations, requires that the
installation of an unvented system should be notified to the
local authority Building Controls Department and that the work
must be carried out by a competent person approved at the
time by the Health and Safety Executive, as defined in the
approved document G3.
For IE: The current edition of I.S.813 “Domestic Gas
Installations”.
Where a storage system will not have a vent to atmosphere
the installation must comply with the building regulations and
the Water Supply (water fittings) regulations 1999 and water
byelaws 2000, Scotland, see also the current issue of BS5546
and BS6700.
If fitting to an existing system the local authority should be
informed.
NOTE:
Bye-laws of the appropriate Water Undertake also apply.
Discharge Pipework
It is a requirement of Building Regulation G3 that any
discharge from an unvented system is conveyed to where it
is visible but will not cause danger to persons in or about the
building. The tundish and discharge pipes should be fitted in
accordance with requirements and guidance notes of Building
Regulation G3.
NOTE: The tundishes are factory fitted during manufacture.
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, preferably 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 straight pipe 9m long i.e. discharge
pipes between 9m and 18m equivalent resistance length
should be at least two 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.
An alternative approach for sizing discharger pipes would be
to follow BS67100:1987 specification for design installation,
testing and maintenance of services supplying water for
domestic use within buildings and their curtilages. Appendix E
section E2 and table 21.
b) Have a vertical section of 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 is
practically difficult there should be clear visibility at one or
other of these locations. Examples of acceptable discharge
arrangements are:
i) Ideally below a fixed grating and above the water seal in a
trapped gully.
ii) 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 where children may
play or otherwise come into contact with discharges a wire
cage or similar guard is positioned to prevent contact whilst
maintaining visibility.
iiI) Discharges at high level; e.g. into a 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).
iv) 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
discharging can be traced reasonably easily. The single
common discharge pipe should be at least one pipe size
larger than the largest individual discharge pipe (D2) to
be connected. If unvented hot water storage systems are
installed where discharges from safety devices may not be
apparent i.e. 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.