G4/AS1: Ventilation

G4 VENTILATION ACCEPTABLE SOLUTION G4/AS1 Gas-fuel appliances b) remove exhaust air from the room either: i) mechanically at one third the inlet rate, or ii) naturally via high-level openings having a free ventilation area of no less than 600 mm2 per kW of total gas consumption for all appliances in the room. 3.2.2 Flue construction 3.2.2.1 A flue system shall have: a) the cross-sectional area of a natural draught flue system external to the appliances, no less than the cross-sectional area of the appliance outlet; or b) the flue designed to comply with AS/NZS 5601.1, section 6.7 and Appendix H; and c) if a draught diverter is not fitted: i) flue products discharged to the atmosphere only at the flue terminal, unless the discharge at other locations can be achieved without hazard to persons, property or appliance operation, and ii) a method of automatically shutting down the main burners of forced or induced draught appliances, should the normal free discharge of the flue be interrupted. 3.2.3 Draught diverters 3.2.3.1 Draught diverter installations shall discharge the total flue products including excess air and draught diverter dilution air, at the flue terminal without spillage from the skirt of the draught diverter. 3.3 Flue locations on dwellings 3.3.1 Flue terminals 3.3.1.1 The location of a flue terminal on a dwelling shall have: a) outlets from natural draught flues or chimneys, positioned relative to surrounding construction to avoid wind causing down draughts in the flue; and b) flue pipes which extend through the roof, terminated no closer than: i) 500 mm to the nearest part of any roof, and ii) 2.0 m to the roof level of a flat roof intended for personal or public use, and iii) 500 mm above any parapet; and c) flues which terminate on the wall of a building located clear of inlets for outside air in accordance with the minimum clearances specified in AS/NZS 5601.1, section 6.9 and Figure 6.2. 3.4 Another solution for gas-fuel appliances 3.4.1 Gas installations 3.4.1.1 As an alternative to Sections 3.1, 3.2, 3.3, gas installations may be designed and installed to comply with AS/NZS 5601.1 Sections 1, 3, 4, 5 and 6 and Appendices A – M and O – R. COMMENT: Compliance with this standard may exceed the performance criteria of Building Code clause G4 Ventilation. MINISTRY OF BUSINESS, INNOVATION AND EMPLOYMENT 28 JULY 2025 Page 14