If it is necessary to install a heater closer to a combustible
surface than the stated requirements in Section 2 of this
Installation Guide, it must be done in accordance with
Australian Standard AS/NZS 2918:2001 Section 3, Tables 3.1
& 3.2.
Shield Construction:- The shield shall be constructed from a
heat resistant material. The shield must be fixed to the
surface that requires protection and NOT the heater.
The Standard allows three options to reduce stated
clearances.
Single layer of continuous material with Minimum Air Gap of
12mm—Clearance Factor = 0.40
Single layer of continuous material with Minimum Air Gap of
25mm—Clearance Factor = 0.30
Two spaced layers of continuous material with Minimum Air
Gaps of 12mm + 12mm—Clearance Factor = 0.20
The shielding must be open at the top and bottom (vented)
to allow a continuous air flow. It is this air flow that keeps
the surface requiring protection cool. Fixings should not
impede this air flow.
The shielding needs to go far enough along and up the wall
so that the original side and rear required clearances are not
compromised. As the flue is now closer to the wall the
shielding should also protect the wall from the flue pipe.
For example:
Side wall clearance for the Nectre 15 LE is 750 mm.
A 12mm gapped shield on the wall with a factor of 0.40.
Calculate:- 750 mm x 0.40 = 300 mm. This is the new side
wall minimum clearance.
The shielding needs to be large enough so that none of the
original clearances of 750 mm are compromised.
The flue system used when installing the heater MUST
comply with the current installation standard AS/NZS 2918.
Full instructions on the installation of the flue will be supplied
with the flue kit. These MUST be followed closely, including
the minimum exit height from the top of the floor protector
being not less than 4.6m, and the minimum exit height above
the roof line of roof ridge as detailed in the instructions.
The flue must be fitted with either of the following:
1)
Rear flue shield
– 900 mm long, minimum 160
° arc,
stainless steel unpainted
rear flue shield with 25mm
gap between it and the 150mm diameter active flue, OR
2)
Decro-mesh with 900mm long inner shield :
–
a)
A full length, half radius perforated decro-mesh flue
shield extending from the heater through into the
drop box penetrating the ceiling.
b)
A 900 mm half round stainless steel inner reflector
must be fitted inside the decro-mesh. Using tin-
snips, cut three 10mm tabs into the top and bottom
of the inner reflector. Bend the centre tabs in, and
the ones closest to the edge out to create an air gap
between it, the outer decro-mesh, and the 150mm
active flue.
3. Reducing Clearances to Combustible Walls
4. INSTALLING THE FLUE
Tabs bent out
Tab bent in
