Honeywell Central Heating Cooker Natural Gas manual Installation, GAS Supply

INSTALLATION

1.GAS SUPPLY

1.1The supply pipe from the cooker is 3/4” BSP threaded male. An isolating gas valve must be fitted adjacent to the cooker and the gas installation pipe work must be installed, inspected, tested for soundness and purged in accordance with BS 6891

Nominal inlet gas pressure	20mbar
Maximum gas pressure	25 mbar
Minimum gas pressure
with both burners running	17 mbar

2.FLUE & CHIMNEY REQUIREMENTS

2.1To evacuate the products of combustion safely and thoroughly, the cooker must have an efficient flue system. Reference should also be made to BS 5440 Part 1 & 2 if further information is required on conventional chimneys.

2.2This unit is designed to work on a conventional flue system with a draught of 0.05” +/- 0.02” W.G (12.45 +/- 4.98 Pa or 0.124 +/- 0.498 mbar).

2.3The chimney should rise as vertically as possible and terminate at a point not subject to down draughts or wind eddies.

2.4Brick and masonry chimneys must be lined with a moisture and acid resistant liner of the same diameter as the boiler flue outlet.

2.5A factory made insulated chimney complying with BS 4543 Part 3 may be considered as an alternative to a structural chimney both for new and existing buildings.

2.6The in-built flue gas resistance of the appliance is such that it allows the boiler to operate reliably over the wide range of chimney draughts encountered from typical domestic chimneys. The use of a flexible stainless steel liner is a convenient method of lining an existing chimney and this should be back filled with ‘vermiculite’ or similar insulating material to retain heat. A flexible liner should also be used in chimneys fitted with large diameter clay liners to reduce the flue bore and improve the thermal insulation.

2.7The use of a draught stabiliser should not be necessary nor it desirable since it allows flue noises to be emitted into the room.

Notes:

1.In view of the appliances high terminal efficiency it is important that a liner is fitted, otherwise condensation problems could result.

2.Before fitting a liner, the chimneymust be thoroughly cleaned free from all traces of soot and scale.

3.TYPES OF CHIMNEY AND FLUE SYSTEMS

3.1There are four basic chimney/vent systems that can be used with gas fired appliances.

These are:-

Twin Wall Gas Vent.

3.2A metal twin wall flue system incorporating an air gap of between 6 mm and 20 mm constructed in either all aluminium for external use or aluminium inner and galvanised or stainless steel outer skin recommended for internal use only. Such products shall be certified to BS 715.

Stainless Steel Lined Prefabricated Chimneys.

3.3These chimney systems consist of two skins of stainless steel or a combination of stainless steel and galvanised steel incorporating high quality insulating materials. Depending upon the materials of combustion, these products can be used internally and externally. Such products shall be certified to BS 4543.

Ceramic or Concrete Lined Prefabricated Chimney.

3.4Similarly, constructed to the previous category except that the inner liner is fabricated with either lightweight fireproof concrete or ceramic material. These products shall be certified by the British Board Agreement.

Concrete Block/Masonry Chimneys.

3.5These can be divided into three different categories:-

(i)Conventional brick or masonry construction with either clay to BS 1181 or refractory concrete flue liner manufactured from a kiln burnt aggregate and high alumina cement.

(ii)Prefabricated chimney block systems

(iii)Gas Flue blocks.

3.6Category (i) is the conventional chimney and in the majority of installations where used with a gas appliance it will be necessary to utilise a stainless steel flexible liner. The second category (ii), prefabricated block chimney systems are designed to accommodate quite a range of heating appliances, gas appliances included. In some cases they may need to be lined with a flexible liner. The appliance manufacturer and chimney manufacturer should be consulted for guidance. The final category (iii), gas flue blocks consists of a narrow rectangular flue way within a building block normally used as part of the internal or external construction of the house.The flue way is usually very narrow, and the systems are often linked with twin wall gas vent to which they are “adapted” in the roof space, after which the gas vent completes the chimney run through termination. Such systems should be carefully inspected for soundness before being used. If they are incorrectly constructed they can contribute to operational difficulties and in particular condensation within the chimney system as a whole. If any doubts should arise as to the condition of such chimney systems they should be carefully checked and possibly replaced with a new flue system.

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