901
10
Flue system
The boiler allows the flue outlet to be taken from the rear of the boiler or from either side.
A standard flue length of 0.75 metres is provided. Alternative lengths of two or three metres can be supplied
(equivalent to wall thicknesses of up to 565, 1815 and 2815 mm for rear flues and deduct 91 mm plus distance
from side wall for side outlet flues).
It is absolutely essential, to ensure that productsofcombustiondischarging from the terminalcannotre-enter
the building, or enter any adjacent building, through ventilators, windows, doors, natural air infiltration, or forced
ventilation/air conditioning.
Gas Supply
If necessary the local Gas Region should be consulted, at the installation planning stage, in order to establish
the availability of an adequate supply of gas.
An existing service pipe must not be used without prior consultation with the Local Gas Region.
A gas meter can only be connected by the Local Gas Region, or by a Local Gas Region's Contractor.
Installation pipes should be fitted in accordance with BS6891-1988.
Appliance inlet working pressure must be 20 mbar MINIMUM.
Pipework from the meter to the combination boiler must be of an adequate size.
The boiler requires 3.3 m3/h (116 ft3/h) of natural gas.
Do not use pipes of a smaller size than the combination boiler inlet gas connection.
ThecompleteinstallationmustbetestedforgassoundnessandpurgedasdescribedinBS6981-1988.Allpipework
must be adequately supported. An isolating gas valve is provided and should be fitted on the manifold assembly.
Water System
Central Heating
It must be a sealed system. Detailed recommendations are given in BS6798, BS5449, BS6700 and CP342
Part.2.Pipeworknot forming part of the useful heating surface shouldbeinsulatedtopreventanyheatlosses
or possible freezing (i.e. in roof spaces or ventilated underfloor spaces). Drain taps should be positioned at
the lowest point of the system in accessible locations to permit the whole system to be drained down. The
draintapsshould be in accordancewithBS2879. Copper tubingto BS2871, Part. 1 is recommended for water
carrying pipework. Pipework in horizontal runs should have a gradient where possible to facilitate the removal
of air. Itshouldbe ensured thattheboiler heat exchangerisnot a naturalpointfor collectingair.A typical heating
system with domestic hot water circuit is illustrated in fig. 6.
Important - A bypassmustbefittedtoensureaminimumflowratethroughtheboilerof6l/min.Thebypassshould
be fitted as far as possible from the boiler if thermostatic radiator valves are fitted throughout.
Make up Water
Provision must be made for replacing water lost from sealedsystem. Reference should be made to BS6798,
for methods of filling and making up sealed systems. There must be no direct connection between the boiler's
centralheatingsystemandthemains water supply. Theuseofmainswatertochargeandpressurisethesystem
directly,is conditional upon the LocalWater Byelaw.Again any suchconnection mustbe disconnected after use.
Domestic Hot Water
Always fit a water softener or descaler in «hard water areas». A 15 mm copper connection point on the boiler
jig bracket for attaching to the main supply is provided. The maximum domestic water pressure for the inlet supply
is10bar(145P.S.I.).Ifthecold mainssupplyexceeds5bar(72P.S.I.),awatergovernororpressurereducingvalve
must be fitted by the installer into the mains supply in an inconspicuous but accessible position preferable between
3 and 5 metres (10-16 ft) before the appliance. Such a valve must be approved by the Water Research Council.
Attention - Is drawn to the Model Water Byelaws.
Fittings manufactured from duplex (alpha-beta) brass are notacceptableforundergrounduseandcertain
water undertakings will not accept their use above ground.
