Technical Booklet L Combustion Appliances and Fuel Storage Systems·Page 17·Diagram 1.3
Classification of Combustion Appliances by Flue Type and Operation
Combustion appliances are classified into three main types (A, B, C) based on their method of evacuating products of combustion, with further numerical qualifications indicating the existence and mode of use of fans and draught diverters.
The letters A, B and C are further qualified by numbers to identify the existence and mode of use of fans and draught diverters, as applicable (e.g. B11 for an open-flued natural draught appliance with draught diverter).
Type A - Flueless appliances
Type B - Open-flued
Type C - Room-sealed
Open-flued Room-sealed
Natural draught installation
Fanned draught installation
Forced draught appliance
Flueless
Note: CEN CR1749 classifies gas appliances according to their method of evacuating the products of combustion.
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