RELATIONSHIP TO COMBUSTIBLE MATERIALS
(F4.17) The requirements of F4.17 will be met by -
a. a constructional hearth at least 125mm thick and with plan dimensions in accordance with the diagrams to this specification; or
b. where the appliance will not cause the temperature of the top surface of the hearth on which it stands to be more than 100º C, a free-standing, solid, non-combustible hearth at least 12mm thick.
Diagrams to (F4.17a): Constructional hearth sizes
Diagram
(F4.18) The requirements of F4.18 will be met where the appliance is positioned on a hearth in accordance with the diagrams to this specification -
Diagram 1 to (F4.18): Locating a solid fuel appliance on a hearth
Diagram
Notes:
1. The 150mm does not apply where the appliance is located in a fireplace recess, nor does it apply where the back or sides of the hearth either abut or are carried into a solid, non-combustible wall complying with (F4.19b).
2. A solid fuel appliance may be located on a superimposed hearth provided the superimposed hearth is positioned partly or wholly on a constructional hearth in accordance with Diagram 2 to (F4.18).
Diagram 2 to (F4.18): Locating a solid fuel appliance on a superimposed hearth
Diagram
Notes:
1. In this specification -
SUPERIMPOSED HEARTH means a finish of solid, non-combustible material, usually decorative, at least 50mm thick and positioned on a constructional hearth.
2. The 150mm does not apply where the appliance is located in a fireplace recess, nor does it apply where the back or sides of the hearth either abut or are carried into a solid, non-combustible wall complying with (F4.19b).
3. At least 225mm for a closed appliance.
4. At least 300mm for an open appliance and for a closed appliance that may properly be used with its front open.
5. No part of the appliance shall project over any edge of the constructional hearth.
6. At least 150mm to combustible material measured horizontally.
(F4.19) The requirements of F4.19 will be met where -
a. the hearth is located in a fireplace recess in accordance with BS8303: Part 1: 1994; or
b. any part of the building, other than the floor, not more than 150mm from the hearth, is constructed of solid, non-combustible material in accordance with the diagram and table to this specification -
Diagram to (F4.19b): Solid fuel appliance or hearth adjacent to any part of a building
Diagram
Table to diagram (F4.19b): Hearth and appliance adjacent to any part of a building
|
Location of hearth or appliance |
Thickness (T) of solid, non-combustible material |
Height (H) of solid non-combustible material. |
|
where the hearth abuts a wall and the appliance is not more than 50mm from the wall |
200mm |
at least 300mm above the appliance or 1.2 m above the hearth whichever is the greater. |
|
where the hearth abuts a wall and the appliance is more than 50mm but not more than 300mm from the wall |
75mm |
at least 300mm above the appliance or 1.2 m above the hearth whichever is the greater. |
|
where the hearth does not abut a wall and is not more than 150mm from the wall [Note 1] |
75mm |
at least 1.2 m above the hearth. |
Note:
1. There is no requirement for protection of the wall where X is more than 150mm.
(F4.21) The requirements of F4.21 will be met by -
a. a fireplace recess, incorporating a constructional hearth, constructed in accordance with Clauses 7 and 8 of BS8303: Part 1: 1994, and to the minimum thickness shown in Figure 2 to BS8303: Part 3: 1994; or
b. a prefabricated appliance chamber of solid concrete components which -
i. is connected to a chimney or flue-pipe, and
ii. is supplied by the same manufacturer, with pre-made jointing arrangements, assembled on site using a cement specified for the purpose by the manufacturer, and
iii. is of insulating concrete with a density of between 1 200 and 1 700 kg/m3, and
iv. is installed on a constructional hearth, and
v. has components of the minimum thickness shown in the table to this specification -
Table to (F4.21b): Thickness of solid fuel appliance chamber components
|
Component |
Minimum thickness (mm) |
|
Base |
50 |
|
Sides |
75 |
|
Back panel and top slab |
100 |
|
Hood and bar lintels |
100 |
OIL-FIRED COMBUSTION APPLIANCE INSTALLATIONS
(F5.2) The requirements of F5.2 will be met by an appliance that complies with the OFTEC Standard appropriate for the class of the appliance.
(F5.3) The requirements of F5.3 will be met where the oil-fired appliance is provided with an air supply in accordance with Section 4 of BS5410: Part 1: 1997.
(F5.4) The requirements of F5.4 will be met where the oil-fired appliance, located in an appliance compartment, is provided with air for cooling in accordance with Clause 4.4.3 of BS5410: Part 1: 1997.
REMOVAL OF PRODUCTS OF COMBUSTION
(F5.7) The requirements of F5.7 will be met where the chimney or flue-pipe is constructed and installed in accordance with the requirements of BS5410: Part 1: 1997.
(F5.8) The requirements of F5.8 will be met where the flue gas temperature is measured in accordance with OFTEC Appliance Standard OFS A100 for boilers or OFS A101 for cookers.
(F5.10) The requirements of F5.10 will be met where the terminal is separated from openings, obstructions or combustible material by at least the distance shown in the diagrams and table to this specification -
Diagram 1 to (F5.10): Flue terminal positions for oil-fired appliances
Diagram
Table to diagram (F5.10): Flue terminal positions for oil-fired appliances
|
Location |
Minimum distance to terminal in mm |
|
|
Pressure Jet |
Vaporising |
|
|
A Directly below an opening, air brick, opening window etc |
600 |
n/all |
|
B Horizontally to an opening, air brick, opening window etc |
600 |
n/all |
|
C Below a plastic/painted gutter, drainage pipe or eaves, with protection |
75 [5] |
n/all |
|
D Below a balcony or a plastic/painted gutter, drainage pipe or eaves |
600 |
n/all |
|
E From vertical sanitary pipe work |
300 |
n/all |
|
F From an internal or external corner |
300 |
n/all |
|
G Above ground or balcony level |
300 |
n/all |
|
H From a surface or boundary facing the terminal |
600 [6] |
n/all |
|
J From a terminal facing the terminal |
1200 |
n/all |
|
K Vertically from a terminal on the same wall |
1500 |
n/all |
|
L Horizontally from a terminal on the same wall |
750 |
n/all |
|
M Above the highest point of an intersection with the roof |
600 [1] |
1000 [7] |
|
N From a vertical structure to the side of the terminal |
750 [1] |
2300 |
|
O Above a vertical structure not more than 750mm from the side of the terminal |
600 [1] |
1000 [7] |
|
P From a ridge terminal to a vertical structure on the roof |
1500 |
n/all |
Notes:
1. Terminating positions M, N, and O for vertical balanced flues should be in accordance with manufacturer’s instructions.
2. Vertical structure in N, O and P includes tank or lift rooms, parapets, dormers etc.
3. Terminating positions A to L are only permitted for appliances that have been approved for low level flue discharge when tested to OFTEC Standard OFS A100 for boilers or OFS A101 for cookers.
4. Terminating positions must be at least 1 800mm from an oil storage tank unless a wall with at least 30 minutes fire resistance and more than 300mm higher and wider than the tank is provided between the tank and the terminating position.
5. Where a flue terminates not more than 600mm below a projection and the projection is plastic or has a combustible finish, then a heat shield of at least 750mm wide must be fitted.
6. The distance from an appliance terminal installed at right angles to a boundary may be reduced to 300mm in accordance with Diagram 2 to (F5.10).
7. Where a terminal is used with a vaporising burner, a horizontal distance of at least 2 300mm is required between the terminal and the roof line.
8. Notwithstanding the dimensions above, a terminal should be at least 300mm from combustible material.
9. n/all = not allowed.
Diagram 2 to (F5.10) Separation between a boundary and terminal at right angles