Grant EUROFLAME 50/70 User, Installation And Servicing Instructions page 16

Minimum size of air vents required - see Figs. 7 and 8
50/70
Vent A 113 cm² (18 in²)
Vent B 226 cm² (36 in²)
Vent C 85 cm² (13 in²)
Vent D 226 cm² (36 in²)
Vent E 338 cm² (52 in²)
Note: If the boiler is in a compartment, this must be added to the areas required for ventilation.
Fig. 8 - Combustion and ventilation air supply for conventional flue boilers
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3 - GENERAL BOILER INFORMATION
Fig. 7 - Air supply for room sealed balanced flue boilers
50/90, 70/90
145 cm² (23 in²)
290 cm² (46 in²)
118 cm² (18 in²)
290 cm² (46 in²)
436 cm² (68 in²)
Euroflame Oil Boilers
90/120
194 cm² (30 in²)
388 cm² (60 in²)
166 cm² (26 in²)
388 cm² (60 in²)
580 cm² (90 in²)