Stuv 21 - How Does Your StûV 21 Work

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SN 34245 - 132149
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Stûv 21 - directions for use [en] - 0118
How does your Stûv21 work ?
It heats !
When the stove is working (i.e.when
the lighting stage is finished) the
bed of embers will glow and the
logs will produce large flames. The
temperature in the combustion
chamber[a] is very high and the heat
dissipates in two ways :
– by radiation through the glass door,
– also by convection : the air circulates
in the double wall[b] around the
combustion chamber and reheats
before dissipating around the
room[c].
Conserving heat
The flue[d] is full of hot gases that
are much lighter than the air outside
and therefore rise out of the flue that
is holding them. The flue therefore
literally sucks in the gases contained
in the stove. However, it is important
that the gases and the heat that they
contain do not escape too easily from
the flue [fig.1: operation in closed-
door mode].
Two mechanisms stop them :
– firstly, the air needed for
combustion cannot get into the
stove unless the regulator lever is
used[e] – this allows you to control
the quantity needed to obtain the
desired rate ;
– the hot gases cannot enter directly
into the flue : they have to pass
through a system of deflectors[f]
which form a second bottleneck.
Owing to these bottlenecks, the
heat increases in the stove which is
one of the objectives aimed at. The
higher the temperature is, the more
fully combustion takes place (better
efficiency) and the lower the level of
noxious waste.
Exactly what’s required
where it’s required !
The air required for combustion
is strictly reduced to the amount
necessary and, when the stove is in
operation, it is distributed as follows :
– a small amount feeds the base
of the flames via the valve, You
determine the rate at which the
stove operates by adjusting the
amount of combustion air using this
valve[e] ;
– another amount of air penetrates
into the combustion chamber
through slits on either side of the
stove's opening. It sweeps the
glass door to prevent smoke from
condensing there and inflames the
residual gases in the upper part of
the stove. This is commonly known
as post-combustion.
In open-fire mode... [fig. 2]
... You can enjoy the crackling of the
embers, the scent of the wood fire
and the pleasant sensation of heat
radiated directly from the flames of
the primitive fire.
... But your stove heats less well and
consumes more wood.
Lots more air floods into the
combustion chamber[a]. The gases
(and the heat they contain) are
less impeded and escape much
more quickly into the chimney [d].
Combustion is therefore incomplete.
Your Stûv21 provides optimal and
eco-friendly heating as well as greater
efficiency in the “closed” position.
Therefore, we recommend this mode
of usage and advise you to restrict use
in open-fire mode to short periods
(e.g. barbecues).