Technical Booklet L Combustion Appliances and Fuel Storage Systems·Page 56·4.9
Example calculation of free area of air vent for open-flued boiler
Demonstrates the method for calculating cooling air and combustion air vent areas for a 15 kW open-flued boiler using Diagram 4.2 methodology.
An open-flued boiler with a rated input of 15 kW (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 –
The cooling air is exhausted via vent D, which has an area of –
15 x 500 = 7500 mm2
The cooling air and the air needed for combustion and the safe operation of the flue enters via vent E, which has an area of –
15 x 1000 = 15000 mm2
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