unswitched three pin plug and a shuttered socket-outlet, both complying with the
requirements of BS 1363.
The appliance must be connected to the supply via a fused double pole switch
having at least 3mm (1/8 inch) contact separation in both poles, serving only the
boiler and the system.
The connection point to the mains supply should be readily accessible and
adjacent to the boiler, except for rooms containing a bath or a shower. Refer to
section 2.3 Position.
2.4.2
External Wiring & Controls
1.
The boiler is deisgned so that
all
control wiring is external to the boiler.
Hence, any programmers or room thermostats etc must act by switching
the 230V supply to the boiler.
2.
System designs which allow the boiler to fire when there is no pumped
circulation must
NOT
be used.
3.
A programmer may be used with zone valves to give independent control
of central heating and hot water.
2.5
BOILER SIZE SELECTION
The size of the boiler to be used is determined by the total calculated heat loss of the
building. Match the calculated heat loss with the boilers rated output.
If a boiler is installed
with an output rating greatly exceeding the total capacity of the distribution system the
efficiency of the boiler will be reduced.
2.6
GAS SUPPLY
A gas meter should be connected to the service pipe by the local gas region or their
contractor. An existing meter should be checked preferably by the gas region to ensure
that the meter is adequate to deal with the rate of gas supply required. Installation pipes
should be fitted in accordance with BS 6891.
Minimum/Maximum Natural Gas Pressure:
Natural gas pressure before the gas valve must be maintained at 20 mbar (8 in WG) while
the boiler is running.Gas pressures above or below this level 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 (22 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.
A gas cock is supplied loose with the boiler. This cock should be fitted in the gas line to
the boiler as close to the boiler as possible so that it is easily identified as the cock to
isolate the boiler.
2.7
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.
WD51/2/1997 Chapter 2 - Boiler Connections The Keston 170 Condensing Boiler
Installation & Servicing Instructions
Page : 6
