Installation manual

Installation and servicing instructions strictly reserved for qualified gas installers
17
5.1.3 Tundish discharge
The internal safety valves, 24 and 36 have
been tee’d together and the discharge
pipe run so that it exits at the right hand
bottom of the boiler (see chapter «Block
diagram»).
The tundish (supplied) must
be used with this outlet within the normal
guidelines and code of practice and must
be installed so that it is visible to the
occupants and positioned away from any
electrical devices.
It is necessary, during installation,
to connect a 22 mm diameter metal
discharge pipe to a suitable position
outside the building. It is permissible to
use copper pipe.
Warning! 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:
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 i.e. discharge
pipes between 9m and 18m equivalent
resistance length should be at least
larger than the nominal outlet size of
the safety device, between 18m and
27m at least 3 sizes larger
, and so on.
Bends must be taken in to account in
calculating the flow resistance.
Have a vertical section of pipe at least
300mm long, below the tundish before
any elbows or bends in the pipework.
Be installed with a continuous fall.
Be positioned away from any electrical
appliances.
Have discharges visible at both the
tundish and the fi
nal point of discharge
but where this is not possible or
practically difficult there should be
•
•
•
•
•
clear visibility at one or these of these
locations. Examples of acceptance
discharge arrangements are:
Ideally
below a fixed grating and above
the waterseal in a trapped gully.
Downward discharges at a low level;
i.e. up to 100mm above external
surfaces such as car parks, hard
standing, grassed areas etc. are
acceptable providing that where
children may play or otherwise come in
to contact with discharges, a wire cage
or similar guard is positioned to prevent
contact, whilst maintaining visibility.
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 into
a roof capable of withstanding high
temperature discharges of water and
3m from any plastics guttering systems
that would collect such discharges
(tundish visible).
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
least one pipe size larger then 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 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.
Note: the discharge will consist of scalding
water and steam.
Asphalt, roofing felt
and non-metallic rainwater goods may be
damaged by such discharges.
-
-
-
-