NCC 2019 Volume Two
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Part 3.10.7 Boilers, pressure vessels, heating appliances, fireplaces, chimneys and flues
Appropriate Performance Requirements
Appropriate Performance Requirements
Where an alternative heating appliance is proposed as a Performance Solution to that described in Part 3.10.7, that proposal must comply with—
- Performance RequirementP2.7.3; and
- the relevant Performance Requirements determined in accordance with A2.2(3) and A2.4(3) as applicable.
Acceptable Construction Manuals
3.10.7.0 Application
Performance RequirementP2.7.3 is satisfied for a heating appliance if it is installed in accordance with one of the following:
(a)
* * * * *
(b)
Domestic solid-fuel burning appliances: AS/NZS 2918.
Acceptable Construction Practice
3.10.7.1 Application
Compliance with this acceptable construction practice satisfies Performance Requirement P2.7.3 for heating appliances.
3.10.7.2 Open fireplace construction
An open fireplace, or solid-fuel burning appliance in which the fuel-burning compartment is not enclosed must have—
(a)
all masonry constructed in accordance with Part 3.3; and
(b)
a hearth constructed of stone, concrete, masonry or similar non-combustible material so that—
(i)
it extends not less than 300 mm beyond the front of the fireplace opening and not less than 150 mm beyond each side of that opening; and
(ii)
its upper surface does not slope away from the back hearth; and
(iii)
combustible material, such as flooring or framing members below the hearth, is situated not less than 150 mm from the upper surface of the hearth (see Figure 3.10.7.1); and
(c)
walls forming the sides and back of the fireplace up to a height of 300 mm above the underside of the arch or lintel which—
(i)
are constructed in 2 separate leaves of solid masonry not less than 180 mm thick, excluding any cavity; and
(ii)
do not consist of concrete block masonry in the construction of the inner leaf; and
(iii)
are constructed of masonry units with a net volume, excluding cored and similar holes, not less than 75% of their gross volume, measured on the overall rectangular shape of the units, and with an actual thickness of not less than 100 mm; and
(d)
the fireplace must be constructed on footings complying with 3.2.5.5.
Figure 3.10.7.1 Fireplace clearance from combustible materials
3.10.7.3 Chimney construction
The construction of a chimney must comply with Part 3.3 and the following:
(a)
The walls of the chimney above the level referred to in 3.10.7.2(c) must be lined internally to a thickness of not less than 10 mm with composition mortar parging.
(b)
The chimney or flue must terminate not less than 300 mm above the highest part of the building within a horizontal distance of 3.6 m of the chimney or flue (see Figure 3.10.7.2).
Explanatory information:
Explanatory information:
The requirements of this Part are to be read in conjunction with the building sealing requirements in Part 3.12.3. However, it should be noted that Part 3.12.3 does not apply in all States and Territories.
Figure 3.10.7.2 Section showing height and position of chimney
3.10.7.4 Installation of insert fireplaces and flues
An insert fireplace and flue must comply with the following:
(a)
The insert fireplace must be tested and passed the tests required by AS/NZS 2918.
(b)
The insert fireplace must be fitted into a masonry fireplace (including chimney) constructed in accordance with Part 3.3.
(c)
The flue must be double skin and have been tested and pass the tests required by AS/NZS 2918.
Figure 3.10.7.3 Typical installation of fireplace flue inserts
(d)
There must be a clearance of 50 mm between the outer flue and adjacent materials.
(e)
The flue must terminate in accordance with Figure 3.10.7.2.
(f)
The hearth must be constructed in accordance with 3.10.7.2(b) and (d).
3.10.7.5 Installation of free standing heating appliances
The installation of a free standing heating appliance must comply with the following:
(a)
The appliance must—
(i)
be installed with safety clearances determined by testing in accordance with AS/NZS 2918; or
(ii)
be located not less than 1.2 m from adjoining walls (other than a masonry wall); or
(iii)
have a heat shield between the adjoining wall (other than a masonry wall) and the heating appliance in accordance with Figure 3.10.7.4 Diagrams a and b.
(b)
Where a heat shield is used, it must be installed in accordance with Figure 3.10.7.4 Diagram a and b and it must be not less than 90 mm thick masonry constructed in accordance with Part 3.3.
(c)
The heating appliance must be installed on a hearth—
(i)
complying with 3.10.7.2(b), except that the hearth must extend 400 mm from the appliance in accordance with Figure 3.10.7.4 Diagram a and b; or
(ii)
where a heat shield is installed, in accordance with Figure 3.10.7.4 Diagram a and b.
(d)
The flue must—
(i)
have been tested and passed the tests required by AS/NZS 2918; and
(ii)
be installed in accordance with Figure 3.10.7.5; and
(iii)
terminate in accordance with Figure 3.10.7.2.
(e)
Flue types or installation of flues in areas not specifically covered by Figure 3.10.7.4 Diagram a, b and Figure 3.10.7.5 must be installed in accordance with AS/NZS 2918.
Figure 3.10.7.4 Acceptable location of free standing heating appliances
Diagram a - Elevation
Diagram b - Plan view
Figure 3.10.7.5 Acceptable flue installation details
Note to Figure 3.10.7.5: Flue pipe size — 150 mm maximum (for other sizes see AS/NZS 2918).
3.10.7.6 Installation of boilers and pressure vessels
The installation of a boiler or pressure vessel heating appliance within a building, must comply with the following:
(a)
The distance between the vent of any explosion relief device and any adjacent wall, roof, ceiling or other solid construction must be calculated in accordance with Table 3.10.7.1.
Table 3.10.7.1 Minimum clearances for explosion relief
Clearance from
Minimum Clearance (metres)
Adjacent wall or ceiling/roof
0.4(V/3)1/3 or 0.4 m, whichever is the greater
Two walls at right angles; or one wall and a ceiling/roof
0.6(V/3)1/3 or 0.6 m, whichever is the greater
Note to Table 3.10.7.1: V is the internal volume of the boiler or pressure vessel being vented, up to the connection of the flue.
(b)
Floor surfaces beneath a boiler or pressure vessel must be water resistant and formed to drain away from supports and structural building elements.
(c)
Where a safe tray is provided to trap liquids, it must be manufactured from a material resistant to corrosion from the contents of the boiler or pressure vessel.
(d)
Building elements surrounding a boiler must be protected from any furnace heat by refractory material or effective air spaces so that—
(i)
steel elements do not exceed a temperature of more than 300°C; and
(ii)
concrete elements do not exceed a temperature of more than 200°C; and
(iii)
timber elements do not exceed a temperature of more than 150°C.
Explanatory information:
Explanatory information:
The requirements of 3.10.7.6 are limited to a boiler or pressure vessel heating appliance within a building. Therefore, the provision does not apply to a boiler or pressure vessel outside of these limitations, such as a portable gas appliance.
Table 3.10.7.1 provides the minimum clearance required which is based on the volume of the space being vented. The minimum clearance is determined by a formula which includes the volume of the space being vented.
The intention of the explosion relief provisions is that, in the event of an explosion, the extent of damage is limited.
The minimum clearance determined in the first row is 0.4 m from an adjacent wall or ceiling/roof.
The minimum clearance determined in the second row is 0.6 m from two walls at right angles, or one wall and a ceiling/roof. This scenario poses a higher risk of damage from over pressure experienced during a deflagration and therefore both the ventilation and clearances are increased.