Circulation Of Convection Air - Stuv 22 Installation Instructions Manual

Circulation of convection air

1
combustion zone
convection zone
2
3
min Max
100% - 133%
100%
Stûv 22 - installation [en] - 02/2015
18
SN 160580- ...
Natural or forced convection ?
Natural convection is sufficient in most
cases [diagram 1].
This configuration obviously allows
easier (no electrical connection) and
less expensive installation and ensures
completely silent operation.
However, a fan unit :
– enables the amount of air to be
increased and for it to be distributed
further : this is vital if you set up
an air circuit with longs lengths of
ducting,
– allows the temperature to be made
constant more quickly in the space
to be heated,
– enables the air temperature to
be reduced in the outlet vents
(therefore preventing combustion
of the ash and the depositing of ash
on the surrounding plasterwork),
Air passage
Hot air is more voluminous than cool
air. To facilitate the abstraction of hot
air, more air outlets to the stove than
inlets are required.
Therefore, if you open two air inlet
holes in the base of the stove, you
min. 2%
have to open three in the outlet.
In France : minimum of 400 cm² for
the inlet and 500 cm² for the outlet.
Other regulations to be observed :
air inlet section
air outlet section
These air sections must correspond to
the vents opened on the system.
Examples in the table below.
air inlet
section
320 cm
2
320 cm
2
320 cm
2
Configuration of the ducts
If you do not install a fan, ducts are
not mandatory. However, please
note that a fibrous insulating material
inserted in the recess can give off
volatile particles. In this case, thanks
to the ducts, any contact between the
convection air and these materials can
be avoided.
Whether you install a fan or not, the
ducts must rise in a gradual gradient
(min 2%) towards the outlet to
prevent heat traps [diagram 2].
To ensure balanced air flow, the
duct system has to be configured
symmetrically (number of ducts, their
height, the number of bends, their
degree of insulation). This factor is
even more important with natural
convection than forced convection.
In practice...
The ducts have a diameter of 150 cm.
The air inlets and outlets have to be
set up so they cannot be obstructed.
If you install grills on the air inlets/
outlets, ensure that the passage of
useful air in these grills (surface of
the openings) is at least equivalent to
the section of the air inlets/outlets to
prevent pressure loss.
≥ 2/3
air outlet air inlet section
section air outlet section
320 cm 1 ≥ 2/3
2
640 cm 1/2 < 2/3
2
500 cm 2/3 ≥ 2/3
2
number of vents to open
on the fireplace
OK 2 inlets / 2 outlets
OK 2 inlets / 4 outlets