Technical Booklet L Combustion Appliances and Fuel Storage Systems·Page 69·Diagram 5.1
Free areas of permanently open air vents for oil-fired appliance installations
Diagram 5.1 specifies the required free areas (in mm² per kW output or input) for permanently open vents serving oil-fired combustion appliances, with different requirements depending on whether appliances are open-flued or room-sealed and whether they are located in rooms, spaces, or dedicated appliance compartments.
A = 550 mm2 per kW output (see Note 3 and 5)
D = 550 mm2 per kW output
E = 1100 mm2 per kW output
A = 550 mm2 per kW output (see Note 3 and 5)
B = 1100 mm2 per kW output
C = 1650 mm2 per kW output
H = 550 mm2 per kW output
J = H see para 5.3
F = 1100 mm2 per kW input (net)
G = F
No vent needed
Notes:
1. A, D, E, H and J are permanently open vents to the outside. B, C, F and G are permanently open vents between an appliance compartment and a room or space.
2. The area given above is the free area of the vent(s) or the equivalent free area for ventilators of more complex design.
3. Vent A should be increased by a further 550 mm2 per kW output if the appliance is fitted with a draught break.
4. Vents at C, E, G, and J are low level vents. Vents at B, D, F, and H are high level vents.
5. In older dwellings with an air permeability which is more than 5.0 m3/h/m2 the first 5 kW (net) can be ignored.
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