Flue termination clearances
There are stipulations for all flue terminations whether they terminate on a roof or external wall of a building. This is to ensure that combustion products cannot re-enter windows, grills or air inlets.
Terminating a flue above a roof
Flues that extend to a roof must terminate with a minimum of 500mm from the nearest part of the roof. This means the steeper the roof the greater the flue length will be. The flue end should be at least 1000mm horizontally from any neighbouring structure. If less than this it must end at least 500mm above the structure. If a number of flue terminations are on a roof they must be located at least 300mm apart.
Other flue terminal locations
Flue terminals must not be positioned within certain distances of the gas meter, windows or doors (to prevent product combustion re-entry), or electrical meters. Ensure that the position of the terminal complies with, or exceeds, the minimum distances from building openings and corners, in accordance with NZS5261:2003, Table 16 – minimum clearances required for flue terminals.
Natural draft flues
Natural draft flue terminals must follow the requirements of NZS5261:2003, Table 16 - minimum clearances required for flue terminals.
As a general guideline they should be positioned where wind can blow freely across at all times and where combustion products cannot re-enter windows, grills or air inlets.
Please note:
- Flue terminals should not be installed where they can be touched, especially by children (protective casings are available), and must be clear of any obstructions and shrubbery.
- ALWAYS refer to appliance manufacturer specifications for details on individual appliances.
Minimum clearances required for flue terminals (ref: Table 16, NZS 5261:2003)
| Ref | Item | Minimum clearances (mm) | |
|---|---|---|---|
| Natural draught | Fan forced | ||
| a | Below eaves, balconies and other projections: - Gas appliances up to 50 MJ/hr input - Gas appliances over 50 MJ/hr input |
300 500 |
200 300 |
| b | From the ground, above a balcony or other surface (see Note 6) | 300 |
300 |
| c | From a return wall or external corner (see Note 6) | 500 |
300 |
| d | From a gas meter (M) (see 2.5.4.9 for vent terminal location of regulator) | 1000 |
1000 |
| e | From an electricity meter or fuse box (P) | 500 | 500 |
| f | From a drain pipe or soil pipe | 150 | 75 |
| g | Horizontally from any building structure (see Note 6) or obstruction facing a terminal | 500 |
500 |
| h | From any other flue terminal, cowl, or combustion air intake (see Note 6) | 500 |
300 |
| j | Horizontally from an openable window, door, non-mechanical air inlet, or any other opening into a building with the exception of sub-floor ventilation: - Gas appliances up to 150 MJ/hr input - Gas appliances over 15 MJ/hr input up to - 200 MJ/hr input - Gas appliances over 200 MJ/hr input - All fan-assisted flue gas appliances, in the - direction of discharge |
500 1500 1500 |
300 500 1500 1500 |
| k | From a mechanical air inlet, including a spa blower | 1500 |
1000 |
| n | Vertically below an openable window, non-mechanical air inlet, or any other opening into a building with the exception of sub-floor ventilation: - Space heaters up to 50 MJ/hr input - Other gas appliances up to 50 MJ/hr input - Gas appliances over 50 MJ/hr input and up - to 150 MJ/hr input - Gas appliances over 150 MJ/hr input |
150 500 1000 1500 |
150 500 1000 1500 |
Notes
- All distances are measured to the nearest part of the flue terminal.
- Prohibited area below electricity meter or fuse box extends to ground level.
- See NZS 5261:2003, 2.6.13.3 for restrictions on a flue terminal under a covered area.
- See NZS 5261:2003, Appendix G LPG Cylinder Locations, figure G2 and figure G3, for clearances required from a flue terminal to an LPG cylinder. A flue terminal is considered to be a source of ignition.
- For gas appliances not addressed above the design shall be certified by a suitably qualified engineer.
- Some gas appliances may be suitable for closer installation; refer to the manufacturer’s instructions.
Minimum clearances required for balanced flue terminals, fan forced flue terminals, room-sealed gas appliance terminals or the terminals of outdoor gas appliances
Key
T Flue terminal
I Mechanical air inlet
M Gas meter
P Electricity meter or fuse box