Ariston GENUS HE 35 Plus Installation And Servicing Instrucnion page 18

18
System Design:
This boiler is suitable only for sealed systems.
Drain Cocks:
These must be located in accessible positions to permit the
draining of the whole system. The taps must be at least 15 mm
nominal size an manufactured in accordance with BS 2870:1980.
Safety Valve Discharge (Primary Water):
The discharge should terminate facing downwards on the exterior
of the building in a position where discharging (possibly boiling
water & steam) will not create danger or nuisance, but in an easily
visible position, and not cause damage to electrical components
and wiring.
The discharge must not be over an entrance or a window or any
other type of public access.
Mains Water Feed - Central Heating:
There must be no direct connection to the mains water supply
even through a non-return valve, without the approval of the Local
Water Authority, and must be in accordance with water supply
regulations. Your attention is drawn to, for GB: Guidance G24.2
and recommendation R24.2 of the water regulations guide and for
IE: the current edition of I.S.813.
Filling:
A temporary method for initially filling the system and replacing
lost water during servicing and initial filling (complying to current
water regulations and byelaws) is provided. The flexible hose
must be removed once the system has been filled.
Domestic Hot Water
Storage Discharge Pipe Work
1) The tundish must be installed directly below the discharge outlet
connection of the boiler. The tundish must also be in a position visible
to the occupants, and positioned away from any electrical devices.
The discharge pipe from the tundish should terminate outside in a
safe place where there is no risk to persons in the vicinity of the
discharge and to be of metal.
2) Discharge pipes from the temperature & pressure relief and
expansion relief valve are joined together within the appliance.
3) The pipe diameter must be at least one pipe size larger than the
nominal outlet size of the safety device unless it's 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 2 sizes larger than the nominal outlet size of
the safety device. Between 18 m and 27 m at least 3 sizes larger, and
so on.
Bends must be taken into account in calculating the flow resistance.
See fig. 10.4 (page 19) and Table 1 (page 20).
4) The discharge pipe must have a vertical section of pipe at least 300 m
in length, below the tundish before any elbows or bends in the
pipework.
5) The discharge pipe must be installed with a continuous fall.
6) The discharge must be visible at both the tundish and the final point of
discharge, but where this is not possible or practically difficult; there
should be clear visibility at one or other of these locations. Examples
of acceptance are:
i) Ideally below a fixed grating and above the water seal in a trapped
gully.
ii) Downward discharges at a low level; i.e. up to 100 mm above
external surfaces such as car parks, hard standings, grassed areas etc.
These 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.