Appendix A: Checklist for checking and testing of hearths, fireplaces, flues and chimneys
Hearth, fireplace, flues and chimneys
The checklist can help you to ensure hearths, fireplaces, flues and chimneys are satisfactory. If you have been directly engaged, copies should also be offered to the client and to the Building Control Body to show what you have done to comply with the requirements of Part J. If you are a subcontractor, a copy should be offered to the main contractor.
Appendix B: Opening areas of large or unusual fireplaces
(SEE PARAGRAPH 2.7)
B1 The opening area of a fireplace should be calculated from the following formula:
B2 Examples of L and H for large and unusual fireplace openings are shown in Diagram 45.
Diagram 45 Large or unusual fireplace openings. (Note: for use with this Appendix, measure L, H and W in mm)
Appendix C: Example calculation of the ventilation requirements of a gas-fired appliance
(SEE DIAGRAM 32)
C1 An open-flued boiler with a rated input of 15kW (net) is installed in an appliance compartment such as a boiler room, which is ventilated directly to the outside. The design of the boiler is such that it requires cooling air in these circumstances.
C2 The cooling air is exhausted via vent D, which has an area:
C3 Vent E allows the cooling air to enter, as well as admitting the air needed for combustion and the safe operation of the flue. It has an area:
C4 The ventilation areas in cm² can be found by dividing the results given above in mm² by 100.
Appendix D: Example calculation of the ventilation requirements of an oil-fired appliance
(SEE DIAGRAM 40)
D1 An open-flued appliance is installed in an appliance compartment such as a cupboard, which is ventilated via an adjoining room. The air permeability of the dwelling is 6.0 m3/(h.m2) at 50Pa. The appliance has a rated output of 11kW,
i.e. 6kW more than the rating at which permanent ventilation openings become necessary for the adjoining room.
D2 Air for combustion and the safe operation of the flue enters the adjoining room partially through infiltration, with the balance entering via vent A, whose area is calculated as follows:
D3 The cooling air for the appliance compartment is exhausted through vent B, which has an area:
D4 All of the air for combustion and the safe operation of the flue as well as cooling air enters the appliance compartment through vent C, which has an area:
D5 The ventilation areas in cm² can be found by dividing the results given above in mm² by 100.
Appendix E: Methods of checking compliance with requirement J2
SEE PARAGRAPHS 1.36 AND 1.54)
E1 This Appendix describes ways of checking the compliance with J2 of existing, relined or new flues, and (where included in the work) the combustion appliance. It applies only to natural draught flues intended for open-flued appliances. The procedures described are used only to assess whether the flue in the chimney, the connecting fluepipe (and flue gas passages in the appliance) are free of obstruction and acceptably gas-tight. In addition, appliance performance tests, including flue spillage tests to check for compliance with J2, should be carried out when an appliance is commissioned to check for compliance with Part L and as required by the Gas Safety (Installation and Use) Regulations.
E2 Tests on flues should be carried out at the most appropriate time during the building work. Where possible, for example, smoke tests should be performed when the structure of a chimney is visible and before the application of finishes such as plaster or dry lining that could obscure sight of smoke leakage during testing.
Testing applications
Tests for existing flues
E3 Flues in existing chimneys can be obstructed by nests, debris resulting from deterioration of the structure (e.g. brickwork, flue lining material or pieces of chimney pot) and by soot and tar. Flues in existing chimneys may also leak as a result of holes or cracks appearing in the structure and linings, particularly at joints. The top, exposed part of a chimney is particularly prone to decay. A way of checking the state of a flue prior to bringing it back into use would be to do the following:
a. Sweep the flue. This is intended to clean the flue to demonstrate that it is essentially free from obstructions and to enable better visual inspection and testing of the flue. Tar deposits caused by burning wood may be especially hard to dislodge and should be removed. The debris that comes down the chimney when sweeping should be examined for excessive quantities of lining or brick that are signs that further repairs are necessary.
b. Carry out a visual inspection of the accessible parts to identify:
Deterioration in the structure, connections or linings which could affect the flue’s gas-tightness and safe performance with the proposed combustion appliance. Examine the interior of the flue and the exterior of the chimney including in the roof-space. The presence of smoke or tar stains on the exterior of a chimney/ breast is a sign of leaks that possibly indicate damage;
Modifications made whilst the flue was
out of service, such as the fitting of a ventilator terminal, which would be incompatible with using the flue with the intended appliance;Correct lining and lining sizes for the proposed new application.
c. Perform checks where necessary to demonstrate that the flue is free from restriction: a visual check may be sufficient where the full length of the flue can be seen. In cases of doubt, a way of checking this would be to carry out a coring ball test.
d. Check the gas-tightness of the flue by carrying out a smoke test.
New masonry and flueblock chimneys
E4 Check during construction that liners are installed the right way up, with sockets facing upwards and joints are sealed so that moisture and condensate will be contained in the chimney.
E5 Flues in new masonry chimneys can be obstructed, particularly at bends, by debris left during construction or by excess mortar falling into the flue or by jointing material extruded from between liners and flueblocks. The flues should be checked to demonstrate that they have been correctly constructed and are free of restrictions and acceptably gas-tight.
A way of checking the condition of a new flue prior to bringing it into use would be to do the following:
a. Carry out a visual inspection of the accessible parts to check that the lining, liners or flueblocks are of the correct materials and of suitable size for the proposed application.
b. Perform checks where necessary to demonstrate that the flue is free from restriction: a visual check may be sufficient where the full length of the flue can be seen. In cases of doubt, a way of checking this would be to carry out a coring ball test or to sweep the flue, which may be more effective at removing flexible debris that might not be dislodged by a coring ball.
c. Check the operation and gas-tightness of the flue by carrying out a smoke test.
New factory-made metal chimneys
E6 A checklist for the visual inspection of a newly completed factory-made metal chimney is given in BS EN 15287-1:2007 and additional checks or particular variants may be included in manufacturers’ installation instructions. Following inspection, the chimney should be subjected to a smoke test.
Relined flues
E7 A flue which has been relined may be checked to show that it is free from restrictions, such as from surplus material (where that can occur) and that it is acceptably gas-tight by using the same tests as would be applied in the case of a newly built flue. However, a flue which has been relined with a flexible metal liner in accordance with Paragraph 3.36 of this Approved Document may be assumed to be unobstructed and acceptably gas-tight. (The use of a coring ball or inappropriate sweeps brushes can seriously damage a flexible metal flue liner.)
Appliances
E8 Where a combustion appliance is provided and connected up to the flue system as part of the work, the complete system of appliance and flue should be tested for gas-tightness in addition to testing the flue separately as above. For gas appliances, an appropriate spillage test procedure is given in BS 5440-1:2008. For oil- and solid-fuel fired appliances, suitable test procedures are given in BS 5410-1:1997 and BS EN 15287-1:2007 Annex O respectively.
Flue test procedures
Coring ball test
E9 This test may be appropriate for proving the minimum diameter of circular flues. It may also be used to check for obstructions in square flues but will not detect obstructions in the corners. (A purpose-made coring ball or plate may need to be used if the flue is rectangular.) It is not applicable to fluepipes and should not be used with flexible metal flue liners. It should be carried out before smoke testing.
E10 A heavy ball, with a diameter about 25mm less than that of the flue, is lowered on a rope from the flue outlet to the bottom of the flue. If an obstruction is encountered, the blockage should be removed and the test repeated.
Smoke testing
E11 Where an existing flue is to be checked with a smoke test, it should first be swept.
E12 Two smoke testing procedures are described below. Test I confirms the gastightness of the whole flue and may be used for one serving a solid fuel appliance or if there is any doubt over the condition of a gas or oil flue. Test II may be used where the flue is to serve a gas-fired appliance. Neither test is a substitute for any spillage or flue draught interference test required when commissioning the appliance. Other smoke testing procedures could be used where these form part of the procedure for the installation of an approved flue or relining system
Smoke test I
E13 All doors and windows in the room served by the flue should be closed. The flue should first be warmed to establish a draught, e.g. with a blow lamp or electric heater. A suitable number of flue testing smoke pellets are placed at the base of the flue, such as in the fireplace recess or in the appliance if it is fitted, and ignited. When smoke starts to form, the base of the flue or fireplace opening should be sealed or the appliance should be closed, so that the smoke can only enter the flue. (For example, the recess opening should be closed off with a board or plate, sealed at the edges or, if the pellets are in the appliance, its doors, ashpit covers and vents should be closed.)
E14 Smoke should be seen to issue freely from the flue outlet or terminal. When this is established, the top of the flue is sealed. The full length of the flue should then be checked, bearing in mind Paragraph E19; there should be no significant leakage. The test should be allowed to continue for at least 5 minutes. The closures at the top and bottom of the flue should then be removed.
Smoke test II
E15 All doors and windows in the room served by the flue should be closed. The flue should first be warmed to establish a draught. A suitable flue-testing smoke pellet is ignited at the base of the flue or in the intended position of the appliance, so that the smoke is drawn into the flue with the rising draught. (If the pellets are placed in a recess at the base of the flue, the opening between the room and the recess should be partially closed, such as with a board, but so as to leave an air entry gap of about 25mm at the bottom.)
E16 Smoke should be seen to issue freely from the flue outlet or terminal and not to spill back into the room. There should be no significant leakage of smoke from the length of the chimney inside or outside of the building.
E17 Smoke tests I and II are in line with the recommendations in BS 5440-1:2008.
Notes in relation to testing
E18 Where warming of the flue is specified, this is intended to establish a draught, but this may take more than 10 minutes in the case of large or cold flues.
E19 Appliances, where fitted, should not be under fire at the time of carrying out the test. During a smoke test, smoke should not emerge from the outlet of any other flue, as this indicates leakage between flues. When checking for smoke leakage from a flue, it should be borne in mind that smoke from a faulty flue can emerge some distance away from the original fault. In such cases, the smoke could emerge from such places as barge overhangs in the end of terrace dwellings or from window reveals in cavity walls.
E20 The purpose of carrying out smoke testing is to check that flue gases will rise freely through the flue and to identify whether there are any faults, such as incorrectly sealed joints or damage that would cause the flue gases to escape into the dwelling.
E21 It should be noted that smoke pellets create a pressure significantly higher than the pressure required in the product standards for natural draught chimneys and for flues having a gas-tightness designation of N1. Flues to this designation are permitted to have a leakage rate of up to 2 litre/s/m² flue wall area. Some smoke leakage may therefore be seen during smoke tests and it can be a matter of expert judgement of whether leakage indicates failure.
E22 However, wisps of smoke visible on the outside of the chimney or near joints between chimney sections do not necessarily indicate a fault. If forceful plumes, or large volumes of smoke are seen, this could indicate a major fault such as an incorrectly made connection or joint, or a damaged section of chimney that requires investigation and remedial action followed by a repeat of the test.
Appendix F: Assessing air permeability of older dwellings in relation to permanent ventilation requirements
F1 The minimum requirements for permanent ventilation for certain appliances depend on a knowledge of the air-tightness of the dwelling where they are to be installed, Dwellings built after 2008 are likely to have evidence of the air-tightness either through an individual air permeability test certificate or through representative testing of the same design of dwelling on the same housing development.
F2 Older houses are unlikely to have been tested but are unlikely to achieve an air permeability of less than 5.0 m3/(h.m2) at 50 Pa unless the building fabric has been substantially upgraded. That would include all or most of the following measures:
Full double (or triple) glazing
Effective closures on trickle vents and other controllable ventilation devices
All external doors with integral draught seals and letter box seals
Internal and external sealing around external doors and window framesFilled cavity or solid walls
Impermeable overlay and edge sealing of suspended ground floors
Careful sealing at junctions between building elements such as between walls and floors or ceilings
Careful sealing around loft hatch
Careful sealing around chimney or flue penetrations
Careful sealing around internal soil pipe
Careful sealing around domestic water and heating pipes passing into externally ventilated spaces
Careful sealing of all service penetrations in the building fabric (electricity, gas, water, drainage, phone, TV aerial, etc.)
Internal warning pipe for WC
All cable channels for light switches and power sockets sealed
All cable entry for lighting and ceiling roses sealed. Recessed lighting should not penetrate ceilings separating loft spaces.
F3 Failure to implement even a few of these measures will typically mean that the overall air permeability will probably exceed 5.0 m3/(h.m2) at 50 Pa. However, individual rooms in some older houses with solid walls and solid floors can be inherently air-tight when fitted with modern glazing. The situation may therefore need to be assessed with respect both to the overall dwelling and to the individual room where the appliance is to be fitted. If in doubt then assume that the air permeability is lower than 5.0 m3/ (h.m2) at 50 Pa and fit the appropriate permanent ventilation or seek specialist advice. Further information on sources of air leakage can be found in GPG224 Improving airtightness in dwellings.
Appendix G: European chimney designations
G1 This informative appendix provides a summary of the European chimney designation scheme. The essence of the scheme is a series of code letters based on the general chimney designation scheme of BS EN 1443:2003, an example of which and their explanation is given below.
Designation
G2 The designation of a chimney consists of :
Chimney EN 1234 – T 450 N2 D 1 G50 Number of corresponding chimney standard Temperature class
Pressure class N or P or H Resistance to condensate class, W (wet) or D (dry)
Corrosion resistance class Sootfire resistance class G or O followed by distance to combustible materials
G3 European chimney standards have been developed based on the material of the flue liner e.g. clay/ceramic, concrete, metal, and plastic. Some material based standards have adopted a different shortened designation e.g. for clay flue liners a designation Liner – EN 1457-300-A1-N2 means it is suitable for a chimney with the designation T600 N2 D 3 G, with a nominal size of 300mm.
G4 The designation of the corrosion resistance class of a metal chimney product is dealt with in BS EN 1856-1 and BS EN 1856-2 by a two-fold approach. A minimum material specification and thickness is allowed which is dependent on that which is permitted in member states regulations, where these exist. Products upon which a declaration has been made in this manner are designated Vm. The alternative approach involves the choice of one of three corrosion resistance tests. Products meeting the tests carry the designation V1, V2 or V3, as appropriate allow the product to be designated with the Corrosion resistance class 1, 2, or 3 respectively. The material specification still forms part of the overall designation, and appears alongside the ‘V’ letter, e.g. Vx-L40045. The material specification for the liner (or connecting pipe) is formed by the letter ‘L’ followed by five digits. The first two digits represent the material type and the last three digits represent the material thickness in multiples of 0.01mm.
G5 For the UK, guidance on the minimum material specification appropriate for the various applications in terms of corrosion resistance (solid fuel, gas and oil) is given in the UK National Annex to BS EN 1856-1 and -2.
For further examples of shortened designation refer to the specific product standards.
G6 In selecting an appliance for a given chimney designation, the appliance, irrespective of the fuel used, is required to generate combustion products with characteristics equal or less than those designated for the chimney. When selecting a chimney suitable for a given appliance, any chimney with performance characteristics equal to or higher than those appropriate for the appliance may be used.
Temperature classes
G7 Temperature classes are set out in Table G1 and expressed as ‘T’ followed by a number which is less than or equal to the nominal working temperature, i.e., the average flue gas temperature obtained during the nominal/ rated output test (usually the maximum operating level);
Table G1 Temperature classes
Pressure classes
G8 Pressure classes are set out in Table G2 and expressed as either ‘N’, ‘P’ or ‘H’ followed by either ‘1’ or ‘2’. N relates in general to natural draught chimneys i.e. operating under negative pressure where the value 1 or 2 allows for a different class of product; metal chimneys to BS EN 1856-1 have the class N1. In the UK the value N2 will be assigned as a minimum to masonry chimneys. P and H relate to chimneys which operate under positive pressure e.g. for fan assisted applications and diesel generators respectively. The pressure designation depends on the gas tightness it achieves, the lower number being the more onerous, the higher allowed leakage for positive pressure application being intended to external installations.
Condensate resistance classes
G9 Condensate resistance class – expressed as either ‘W’ for wet or ‘D’ for dry operations. A product designated ‘W’, able to contain condensates within the flue, is aimed at condensing appliances. A product designated ‘D’ would usually have flue gas temperatures high enough to avoid condensate formation.
Corrosion resistance classes
G10 Corrosion resistance classes are set out in Table G3 – this is fuel dependant and expressed as 1, 2 or 3.
Sootfire resistance classes
G11 Sootfire resistance class – expressed as either ‘G’ with sootfire resistance, or ‘O’ without, A product assigned the designation ‘G’ has been tested at 1000ºC for 30 minutes.
Distance to combustible material
G12 The designation of the minimum distance from the outer surface of the chimney to combustible material is given as xx expressed in millimetres (e.g. the distance ‘x-x’ identified in paragraph 1.45 and diagram 13).
Table G2 Pressure classes
Table G3 Corrosion resistance classes (from BS EN 1443-2003)
