Circulation Of Convection Air - Stuv 21 Installation Instructions Manual

Circulation of convection air

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 has more volume than cold
air. Care must be taken to ensure
it is evacuated without generating
a depression in the stove recess (a
deterioration in draught).
Observe the 2/3 relationship with a
minimum of 300 cm². Therefore, if
you open 2 air intake orifices in the
bottom of the stove, you must open 2
or 3 orifices at the outlet.
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 3].
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 are 15 cm in diameter and
therefore have a section of approx.
180 cm .
2
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.
1
2
min Max
100% - 133%
100%
Stûv 21 - installation [en] - 04-2013
SN 132150 - ...
min. 2%
15