REMOVAL OF PRODUCTS OF COMBUSTION
(F4.5) The requirements of F4.5 will be met where the minimum area of the flue is the greater of either -
a. the outlet to the solid fuel appliance; or
b. that set out in the table and diagram to this specification -
Table to (F4.5): Minimum area of flues
|
Appliance |
Position |
Minimum area [Note 2] |
|
Open fire |
a. within a fireplace recess capable of accepting an open fire more than 500mm x 550mm; or b. free standing |
a. 15% of the total face area of the fireplace opening(s); or b. in accordance with the Diagram to (F4.5). [Note 3] |
|
Open fire |
within a fireplace recess capable of accepting an open fire of not more than 500mm x 550mm |
200mm diameter or square section of equivalent area. |
|
Closed appliance with output capacity more than 30 kW but not more than 50 kW |
free standing |
175mm diameter or square section of equivalent area. |
|
Closed appliance with output capacity not more than 30 kW |
free standing |
150mm diameter or square section of equivalent area. |
|
Closed appliance burning smokeless fuel with output capacity not more than 20 kW |
free standing |
125mm diameter or square section of equivalent area. |
Notes:
1. In the table -
SMOKELESS FUEL means solid mineral fuel that produces combustion products containing particulate matter that does not exceed a specified low amount.
2. Any chimney pot or terminal must maintain the same cross-sectional area as the flue.
3. Diagram 1 must only be used for the range of sizes shown within the shaded area.
4. Fire size is related to the free opening area at the front of the fireplace opening.
Diagram 1 to (F4.5): Flue sizing for larger solid fuel open fires
Diagram
Diagram 2 to (F4.5): Fireplace opening areas
Diagram
(F4.8) The requirements of F4.8 will be met by providing access for cleaning in accordance with Clauses 5.4, 9.5 and 10 of BS8303: Part 1: 1994.
(F4.10) The requirements of F4.10 will be met where the outlet is positioned in accordance with the diagrams and table to this specification -
Diagram 1 to (F4.10): Flue terminal positions
Diagram
Table to diagrams (F4.10): Minimum dimension to flue outlets
|
A |
2 300mm horizontally clear of the weather skin. |
|
B |
1000mm provided A is satisfied; or 600mm where above the ridge, except - where the roof is thatch or shingles, as Diagram 2 to (F4.10). |
|
C |
1000mm above the top of any flat roof; and 1000mm above any openable rooflight, dormer or ventilator, etc. within 2 300mm. |
|
D/E |
where D is not more than 2 300mm, E must be at least 600mm. |
Notes:
1. Horizontal dimensions are to the surface surrounding the flue.
2. Vertical dimensions are to the top of the chimney-stack.
Diagram 2 to (F4.10): Flue terminal outlets relative to easily ignited roof coverings
Diagram
PROTECTION FROM PRODUCTS OF COMBUSTION
(F4.11) The requirements of F4.11c will be met where the chimney -
a. is constructed of concrete chimney blocks capable of withstanding a temperature of at least 1000º C and made of, or having inside walls made of, kiln burnt aggregate and high alumina cement jointed and pointed in cement mortar so that no joints, other than bedding joints, directly adjoin the flue; or
b. has purpose made flue linings in accordance with Clause 5.1.5 of BS6461: Part 1: 1984 and any space between the lining and the chimney wall filled with weak mortar; or
c. is a factory-made chimney meeting the requirements of BS4543: Part 2: 1990 and installed in accordance with BS7566: Parts 1 to 4: 1992; or
d. has a lining accepted for the purpose after testing of the chimney under the relevant conditions by a notified body.
(F4.12) The requirements of F4.12 will be met by a flue-pipe that is -
a. manufactured from -
i. cast-iron pipe to BS41: 1973 (1981), or
ii. mild steel at least 3mm thick to Section 1.1 of BS1449: Part 1: 1991, or
iii. vitreous enamelled steel to BS6999: 1989, or
iv. stainless steel numbers 1.4401, 1.4404 or 1.4406 at least 1mm thick to BS EN 10088-1: 1995; and
b. constructed in accordance with Clause 9 of BS8303: Part 1: 1994.