If outdoor vent pipes cannot be installed, two vents should be reserved according to this requirement. The area of each vent must be 0.15 square meters per 100KW of boiler input power.
If outdoor ventilation ducts cannot be installed, two vents should be set aside as required. Each vent area must be 0.15 square meters per 100KW of boiler input power.
If it is not possible to install an outdoor vent, two vents should be left according to this requirement. The area of each vent must be 0.15 m2 per 100kW of boiler input power.