General
The guidance in this Section should be read in conjunction with guidance given in Section 1. The guidance is relevant to combustion installations designed to burn oils meeting the specifications for Class C2 (Kerosene) and Class D (Gas oil) given in BS 2869:2010 or equivalent, liquid biofuel conforming to I.S. EN 14214:2012 and blends of mineral oil and liquid biofuel to OPS 24.
Guidance on the installation of oil burning appliances is contained in: BS 5410: Part 1:1997. Open flued oil-fired appliances should not be installed in such rooms as bathrooms or bedrooms. Room-sealed appliances only should be used if required in these areas.
Oil-firing appliances should be installed, commissioned and serviced to ensure that the entire installation operates safely. Oil firing equipment should be suitable for its purpose and the class of oil used in the installation.
Air supply to appliances
Any room or space containing an appliance (other than a room-sealed appliance) should have a permanent ventilation opening of free area of at least:
550 mm2 per kW of rated output but in no case less than 6,500 mm2 where the air permeability is greater than 5.0m3 /(h.m2 ), or
6,500 mm2 + 550 mm2 per kW of rated output above 5 kW where the air permeability is less than 5.0 m 3 /(hr.m 2 ).
Where room-sealed appliances are contained in compartments, the compartment may require ventilation for cooling purposes (see sub-section 1.2.2).
Note: It is unlikely that dwellings built prior to 2008 would have an air permeability of less than 5 m 3 /h/m2 at 50 Pa unless extensive air tightness measures have been carried out (see Appendix B for further guidance on airtightness of dwellings).
Flues
Size
The flue size for open-flued appliances should be at least:
(a) for a connecting flue pipe, the same as for the flue outlet from the appliance,
(b) for a chimney see Table 7.
Table HJ7 - Flue sizes for chimneys - Extract from TGD J
Direction
For natural draught appliances, horizontal flue runs should be avoided, and if a bend is required in a flue, it should not make an angle of more than 45° with the vertical.
For non-natural draught flues: reference should be made to the appliance or flue manufacturer’s instructions.
Location of flue outlets
The outlet from a balanced flue or low level discharge appliance should be:
(a) so situated externally as to allow the dispersal of the products of combustion and, with a balanced flue, the free intake of air, and
(b) protected with a terminal guard if persons could come into contact with it or if it could be subject to damage, and
(c) designed so as to prevent the entry of any matter which might restrict the flue.
The flue terminal from an oil burning appliance should be positioned in accordance with Diagram 20 and Table 8.
Diagram HJ20 - Flue terminating positions for oil fired appliances - Extract from TGD J
Table HJ8 - Flue terminating for oil-fired appliances - Extract from TGD J
The flue terminals positioned in accordance with the safety distances set out above may not be ideal for condensing boilers which emit plumes of wet flue products.
It is necessary to site a condensing boiler flue terminal such that the plume of wet flue products does not impinge on or significantly affect the use of the dwelling and also the neighbouring buildings. Care may need to be taken to locate flue outlets from condensing boilers away from parts of a building that may be damaged by frequent wetting.
An appliance designed to burn class D fuel should discharge its flue gases at a height of 2 m or greater from the outside ground level. No such limitation is required for an appliance designed to burn class C2 fuel.
Chimneys and connecting flue pipes
General
The minimum I.S EN 1443 designation (see sub-section 1.4.4) for chimneys and connecting flue-pipes for use with oil-fired boilers are shown in Table 9.
Table HJ9 - Chimneys and connecting flue pipes for use with oil-fired boilers - Extract from TGD J
*Connecting flue pipes
Connecting flue pipes as specified in sub-sections 2.4 should generally be acceptable. Where it is known that flue temperatures will not exceed 250o C, connecting flue pipes as specified in subsections 3.8 can be used.
*Masonry chimneys
Masonry chimneys should be lined with any material described in Section 2 for a solid fuel appliance. For condensing appliances, clay/ceramic flue liners with rebated or socketed joints meeting Class B2N1 or B2N2
as described in I.S. EN 1457-2:2012 may also be used. Specific care should be taken where the liners have a water vapour diffusion class of WB, WC or WD. (see manufacturer’s instructions).
The liners should be fitted with the sockets or rebates uppermost. Liners should be jointed with fire-proof mortar, and any space between the liners and the brickwork should be filled with weak 1:1:12 cement/lime/sand mortar or insulating mix (see Section 2.5.3).
Flue block chimneys
Flue block chimneys should be constructed of factory made components suitable for their intended use. They may incorporate a flue or be lined. Flue blocks suitable for use with oil-fired appliances include:
(a) any flue block described in Section 2 as suitable for solid-fuel appliances;
(b) flue blocks meeting the performance level specified in sub-section 4.4.1 for oil-fired appliances. These include:
i) clay/ceramic flue blocks meeting Class FB4 N1 as described in I.S. EN 1806:2006, or FB5 P1 for condensing boilers (see Table A5),
ii) concrete flue blocks meeting Class D1 as described in I.S. EN 1858:2008, or Class G2 for condensing boilers (see Table A6).
Metal system chimneys
Metal system chimneys should be double-walled insulated chimneys as described in Section 2 for solid-fuel appliances. Alternatively metal system chimneys meeting the performance level specified in sub-section
4.4.1 and satisfying the guidance regarding installation set out in sub-section 4.4.5.2 may be used.
A metal system chimney should not:
(a) pass through any part of the building forming a separate compartment, unless it is cased in non-combustible material giving at least half the fire resistance of the compartment wall or floor (see Technical Guidance Document B - Fire Safety),
(b) be placed with its outer wall nearer to combustible material than a distance xx, or
(c) pass through a cupboard, storage space or roof space, unless it is surrounded by a non-combustible guard at a distance of at least xx from the outer wall of the chimney.
For (b) and (c) above, the distance xx should be specified by the manufacturer in accordance with I.S. EN 1856-1:2009 (see Diagram 7).
Rigid or flexible flue liners
Stainless steel rigid or flexible flue liners complying with the appropriate designation of I.S. EN 1856- 2:2009 and meeting the performance level specified in sub-section 4.4.1 may be used in an existing chimney.
Flexible metal flue liners should be installed in one complete length without joints within the chimney. When being installed for an oil appliance in a flue lined chimney it should be sealed at the top and bottom, the space between the chimney and the liner should be left empty unless this is contrary to the manufacturer’s instructions. Flexible flue liners may not be appropriate for large non-lined chimneys without specialist advice.
Hearths
If the surface temperature of the floor below the appliance is:
(a) likely to exceed 100° C, then a constructional hearth should be provided as described in paragraph 2.7.1.1, or
(b) unlikely to exceed 100° C, the appliance may stand on a rigid, imperforate sheet of non-combustible material without a constructional hearth (see sub-section 2.7.1.2).
Shielding of appliances
If the surface temperature of the sides and back of an appliance is likely to exceed 100° C, the appliance should be shielded as described in paragraph 3.11.
Fire valves
Remote acting fire valves should be fitted so as to cut off the supply of oil from the combustion appliance in the event of a fire starting in or around the appliance. They should be temperature rated to suit the installation requirements specified by the appliance manufacturer and should be tested before fitment to prove operation.
For appliances installed inside buildings, the oil supply should be shut off externally to the building. For externally located heating appliances, the oil supply should be cut off at least 1 m away from the appliance.
The valve should be fitted in accordance with the recommendations in Section 8.3 of BS 5410: Part 1:1997 and OFTEC Technical Book 3.
Biofuels
Vaporising burners and appliance installations should not have bio-liquid fuels introduced to them. Bio-liquids in kerosene can immediately adversely affect vaporising burner combustion and manifest in the rapid onset of premature carboning in vaporising sleeve burner bases. Vaporising appliances, such as range cookers, should be converted with appliance manufacturer’s (or appliance manufacturer’s approved) bio-liquid conversion burners.
Pressure jet burners should be adjusted in accordance with the manufacturer’s instructions by a competent person. All equipment designed/converted for biofuels, especially oil storage tanks and oil fired appliances, should be easily and readily identifiable by non-intrusive means with clear and permanent labelling at point of manufacture (or for existing equipment at point of conversion) as only being suitable for bio-liquid fuel blends to I.S. EN 14214:2012 and blends of mineral oil and liquid biofuel to OPS 24.
