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WD388/0/2004
Gas pressures above or below these levels will lead to problems associated with the gas
valve's internal pressure regulator.
Supply pipes to the boiler must not be sized less than the boiler inlet connection
(15 mm). Due consideration must be given to the supply pressure to other gas
appliances in the premises. Reduction in dynamic gas supply pressure will result in
intermittent ignition failures. Ensure gas supply pipe work is adequately sized for
the length of run from the meter to the boiler at a supply rate of 40kW (i.e. a natural
gas supply should be considered to be a minimum of 22mm diameter, reducing to 15mm
at the boiler. If gas runs greater than 12m, including the allowance for bends, are involved
the pipe size should be increased further).
3.7
CH & DHW WATER SYSTEMS
All piping must be installed in accordance with all applicable local and Water Supply
Bylaws for forced hot water heating systems.
Consideration must be given to pipe capabilities and pressure drop through the piping
when selecting pipe sizes. The primary pipe connections to the boiler must be sized
according to the system load, not dictated by the boiler connection sizes.
Water treatment must be carried out to BS 7593 : Treatment of Water in Hot Water
Central Heating Systems.
In IE the requirements given in the current edition of IS813 and the current Building
Regulations must be followed.
a
The Keston C36 Combi is designed for installation on sealed water systems only.
With fully pumped water circulation. The pump, an 8l expansion vessel and
associated safety devices are fitted within the boiler.
b
Any system must be thoroughly flushed clean of grease, dirt and debris, prior to
connection with the boiler. A trap may be installed in the flow line to collect any
solder, or other debris, from the installation.
c
All water systems must be constructed to comply with requirements of the Local
Water Authority.
d
Always use a system complying with the requirements of BS 5449 and BS 6798.
e
System design must ensure an open circuit is always available to ensure
circulation when the pump overrun function is operating after boiler shutdown.
f
Isolation valves must be fitted on the cold mains supply, the heating flow and the
heating return to enable isolation when maintaining the boiler. Such isolation
valves are included in the optional pre-installation jig (C.10C.0.11.00.0)
g
Copper tubing to BS 2871 Part 1 or barrier plastic pipe suitable to 110
Unipipe, is recommended.
h
Jointing should be either with capillary, threaded or compression fittings. Pipes
should have a gradient to ensure air is passed easily to vent points and water
flows readily to drain points.
i
Draining taps must be located in accessible positions which permit the draining of
the boiler. Draining taps should be at least 22 mm in nominal size and be in
accordance with BS 2879. A drain tap is incorporated into the optional
pre-installation jig (C.10C.0.11.00.0)
AIR VENT POINTS
j
These must be fitted at all high points where air will naturally collect and must be
sited to allow complete draining of the system.
Table 3.7 Additional Expansion Vessel Selection
Installation & Servicing Instructions
Chapter 3 - Boiler Location
Safety Valve Setting
Vessel charge & initial system
pressure.
Total Water Content of system in
excess of 125 litres
25 litres
50 litres
75 litres
100 litres
125 litres
The Keston C36 & C36P Combi Boilers
3.0 bar
1.0 bar
Vessel
Volume
2.7
5.4
8.2
10.9
13.6
o
C, such as
Page : 13
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