Technical Booklet L Combustion Appliances and Fuel Storage Systems·Page 60·4.18
Flue outlet terminal for small diameter natural draught open-flued appliances
Natural draught open-flued appliances with a flue diameter not exceeding 170 mm must have an outlet terminal complying with BS EN 1856:1 and BS EN 13502.
A flue serving a natural draught open-flued appliance, with a diameter not greater than 170 mm, should be fitted with an outlet terminal that complies with BS EN 1856: 1, and conforms to BS EN 13502.
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