Understanding CE designations
One of the key features of the European Standard for metal chimneys is a user-readable classification system that designates the features of the product. A label showing the classification must go with each flue component. Understanding the classification can make the job of selecting the right flue much easier and will allow you to compare different flues. It’s easy to use so long as you know the keys. The diagrams below unlocks the coded information.
EN 1443 – T400 N2 D 3 Gxx
the minumum designation required when burning wood in open or closed appliances and coal.
Temperature class – is the maximum flue operating temperature it has been approved for.
Pressure class – is the pressure it has been tested to N negative, P positive, H high pressure. The accompanying number is the amount of leakage at pressure tested at.
Resistance to condensate class – is whether suitable for Dry or Wet application. D or W
Corrosion resistance class – is what type of fuel it may be used for. 1,2,3, (see table)
Sootfire resistance class – G means it has been tested to 1000 deg C for 30 minutes within a test and the gas tightness was still met after the test. The xx is the distance to combustibles declared by the manufacturer when tested.
Please be aware that you can test a chimney without an enclosure and declare a Gxx distance which would give a different result if tested within an enclosure Gxx due to restricted ventilation when enclosed. The letter O means it has not been sootfire tested and thus is not suitable for use with solid fuel. It will show either G or O.
Each type of chimney system has a test method, for a metal chimney it is BS EN1856-1:2009 so within this test we have to meet the general requirements of EN 1443 using specified materials and test methods.
One of the key features of the European Standard for metal chimneys (EN 1856) is a user-readable classification system that designates the features of the product. A label showing the classification must go with each flue component. Understanding the classification can make the job of selecting the right flue much easier and will allow you to compare different flues. It’s easy to use so long as you know the keys. The diagram below unlocks the coded information.
Picking out a few of the main points:
Temperature Rating Maximum temperature (°C) for continuous use of the flue. T400 is suitable for multi-fuel. T200 is suitable for gas and oil.
Corrosion Resistance This is fuel dependent as follows;
V1 Resistant to attack from products of combustion from gas.
V2 Resistant to attack from products of combustion from light oil (sulphur content up to 0.2%) and natural wood. If the flue passes the V2 wet test then it is also deemed to comply with D3 & V3 under dry conditions.
D3 Resistant to the products of combustion from burning wood under dry conditions.
V3 Resistant to attack from products of combustion from heavy oil (sulphur content > 0.2%), solid fuels and peat.
VM Not tested but rating declared by the manufacturer.
Liner Material and Thickness 316L, is the highest quality grade and is expected to withstand the corrosion effect of multi-fuel, wood or heavy oil. The code for 316L is L50. Light oil is less corrosive and normally 304 (L20) has proved adequate in dry conditions, but in the increasingly common wet conditions created by high efficiency condensing boilers, the higher grade is required (316L). The thickness is the steel thickness in mm.
Soot Fire Resistance and Distance to Combustibles Expressed as either G, for soot fire resistance or O for not, followed by the declared minimum distance to combustibles expressed in mm. To obtain the G classification means that the product has been tested at 1000°C for 30 minutes and remains intact. The temperature of combustible material at the designated distance must not exceed 100°C at an ambient temperature of 20°C.
Distance to Combustibles for Connecting Flue Pipe Connecting flue pipes to BS EN 1856-2 also have an additional classification M (Measured) or NM (Not Measured). If not measured the minimum distance to combustibles should be 3 times the internal diameter of connecting flue pipe. Connecting flue pipes to BS EN 1856-1 should be used in accordance with the manufacture’s declared distance to combustibles.
Flue Testing The flue should be fully tested in an enclosed combustible shaft.