Technical Booklet L Combustion Appliances and Fuel Storage Systems·Page 68·5.4
Example of calculation of free area of air vent using Diagram 5.1
This example demonstrates how to calculate the free area of air vents for an 11 kW open-flued appliance installed in a ventilated compartment, with calculations for combustion air, cooling air, and total air requirements.
An open-flued appliance is installed in an appliance compartment such as a cupboard, which is ventilated via an adjoining room. The appliance has a rated output of 11 kW. Air for combustion and the safe operation of the flue enters the adjoining room via vent A, which has an area – (11 – 5 ) x 550 = 3300 mm2. The cooling air for the appliance compartment is exhausted through vent B which has an area – 11 x 1100 = 12100 mm2. 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 – 11 x 1650 = 18150 mm2.
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