BS 5871 part2.
LFE gas fires of heat input not exceeding 15Kw.
It should be noted that the only appliances covered by this part of BS 5871 are those that are CE marked. However BS5871-2 may be used also be referred to for the installation of used appliances, where appropriate, providing the MI are available. In such circumstances, the installer should satisfy himself that the appliance is safe in construction and condition, and can be used without constituting a danger. Attention is drawn to clause 5 concerning this particular aspect.
Arising from the European standards harmonisation, some British Standards appliances specifications are now being replaced by European Standards. One consequence of this process is that the reference clearance flue flow test, currently included in some British Standards covering the safety of appliances dealt with by BS 5871, will not be given in European appliance Standards. This test has hitherto been used to determine the flue flow, under laboratory conditions, that an appliance will just clear its combustion products. The test has been used as a key factor in determining whether or not certain appliances of 7Kw heat input or less require purpose provided ventilation for their installation.
LFE fires.
Flue size: Minimum of 125mm across axis line of flue normally required.
Ventilation; Purpose provided ventilation not normally required up to 7Kw input.
Where appropriate, permanent ventilation shall be provided in accordance with the manufacturer’s instructions.
An open-flued appliance with a rated input not exceeding 7Kw and which generates a clearance flue flow not greater than 70m3/h under specified conditions (see annex B) does not normally require an air vent in the room or internal space in which the appliance is installed. This is due to natural or adventitious ventilation through, for example, floorboards, cracks in window frames and doors, etc. However, the dwelling can be affected by double glazing, cavity wall insulation, draught proofing, its method of construction, the insulation of extraction fans and so on. Attention is drawn to the commentary and recommendations on 19.4 concerning installations deficient in ventilation.
19.4: The fire shall be checked for spillage in accordance with the manufacturer’s instructions.
Where any room of the premises is fitted with a fan (e.g. extract fan or a fan incorporated within an appliance), the operation of the fan (s) shall not adversely affect the performance of the flue when the flue is tested in accordance with BS 5440-1.
The fire should first be tested with all the windows and doors closed in the room of the installation and with any fans in the room running. If there is a fan in an adjacent or nearby room, the test should be repeated with all interconnecting doors open and the fan in operation. If spillage is evident in any of these cases (including the situation in which no fan is present). The test should be repeated with a window slightly open. If the fire now clears its products of combustion then additional ventilation should be provided. Where spillage continues, the fire should be removed and both the appliance and the flue examined; removal of any spigot restrictor may improve the performance.
