NEWS
Heating up with firewood
People have used wood to heat their homes since time
immemorial; today more than two billion people depend on wood
energy for cooking and heating.
8
JUNE / JULY 2019 //
ISH
I
n view of increasing oil prices, the installation of a
modern fireplace or wood burner can contribute to
lowering heating costs and, at the same time, help to
create an atmosphere of well-being in the home.
Individual stoves can today be integrated into the ‘smart’
infrastructure of an existing or new heating system and
with clear, perceptible additional value in terms of energy
consumption. Alongside this, local availability, security of
supply and a cosy flame in the living room are all strong
arguments for wood burners and their ilk.
Decisions must be made between individual units, such
as wood burners and pellet burners, or, on the other hand,
masonry stoves that have been constructed by artisans on
site. Modern wood burners are production items made of
steel or cast iron and have one or more transparent panes,
which enable the flames to be enjoyed. Often encased in
sheet steel, natural stone or ceramics, they heat up very
quickly and give out a pleasant warmth in a very short time.
Wood burners can be installed in every home that has a
suitable chimney.
Pellet burners can provide fully-fledged room heating
and, at first glance, look like traditional wood burners or
tiled stoves. In terms both of the way in which they are
built, and the technology involved, they are, however,
fundamentally different, as the pellet burning stove is
fuelled by small ‘wooden sticks’ that are made from
compressed wood shavings and sawdust. The fuel is fed in
automatically: the pellets are delivered to the combustion
chamber from a storage tank, which is usually integrated
into the stove, via a screw conveyor and then lit
electronically. A thermostat controls the amount of fuel and
the inlet air to achieve and maintain the desired room
temperature.
Tiled stoves are constructed by a stove builder on site
and each one is therefore adapted to the individual home
environment. The tiles are, however, not merely a
decorative feature because they create a ceramic jacket
around the stove and increase its capacity to store heat.
This kind of stove falls into two distinct types: the floor-
fired stove and the warm-air tiled stove and there are also
solutions that involve a combination of the two. The
floor-fired stove is built of solid masonry, using sometimes
more than a tonne of ceramic material that stores heat well.
The logs are burned directly on the floor of the combustion
chamber. Because of its high thermal mass, the stove can
retain heat for up to 24 hours.
The warm-air tiled stove is the modern version, as it
heats up more quickly and delivers heat after only a short
time. Inside there is an industrially produced firebox made
Installing a modern fireplace or wood burner can contribute to
lowering heating costs.
of steel or cast iron. Combined with metal secondary
heating surfaces, this provides rapid heating, or, with a
ceramic heat store, it creates long-lasting heat.
ENERGY REVOLUTION IN THE HOME: HEAT
PUMPS AND WOOD FIRES
With a combination of heat-pump or solar-thermal
installation and a modern fireplace, both space heating and
hot water systems will be fuelled continuously by
renewable and CO 2 neutral energies.
In Germany, there are about 50 manufacturers that offer
more than 1 000 different appliances and versions. While
wood burners and pellet stoves are free-standing individual
units and can be quickly installed or removed, built-in
fireboxes and tiled masonry stoves are, of necessity,
individually designed units that are constructed and
installed by hand by the stove builder. All solid fuel
appliances can be operated in parallel to a heat pump or a
solar-thermal installation and even combined into a single
all-embracing system.
An air-source heat pump, which harvests the available
heat from the surrounding outside air and transforms it into
heating energy, is now installed in one in three new builds
in Germany. The reason is simple: for every kilowatt of
electricity, they produce (on average throughout the year)
four times as much heating energy.
However, the efficiency of these units is dependent on
the temperature of the environment and the heating levels
required. At times of sharp frost – when the demand for
heat is greatest – air-source heat pumps are no longer able
to work efficiently. In such cases, an electric heating
element switches on and provides heat for both the
domestic hot water and the heating system, even though
this leads to high electricity bills. If the external temperatures
are low, then it makes particular ecological and economic
sense to supplement the heating system with a wood-fired
insert in the fireplace, a wood burner or pellet stove.
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