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Subject to change due to technical improvements
Buffer, hot water tank
Buffer, hot water tank
Our heating circuit control system
normally works well without a buffer storage tank
When the boiler can control the heating circuits
itself, it runs for a minimum interval at times of
low heating demand to maintain delivery to the
heating circuits, so it uses the house as a buffer
during periods of slight room temperature variation
(approx. 0.5 °C). If room sensors are installed, the
boiler waits to begin a new firing cycle until the
room temperature actually falls below the target
temperature, thus reducing the number of on/off
cycles to a minimum that saves energy and reduces
wear on the boiler. The transition from firing to
standby is orderly. As long as there is gas-emitting
wood in the combustion chamber, combustion air
continues to be fed in and the resulting residual
heat is supplied to the heating circuits. The control
system calculates the situation in the combustion
chamber from the temperature and the residual
oxygen in the flue gas.
When is a buffer really necessary?
•
When the heat from minimum boiler runtime
cannot be taken up by a hot water tank smaller
than 300 litres during summer hot water
preparation
•
When regulation of the heating elements is done
externally (separately) from the boiler control
system (for example, individual room temperature
control) and the boiler thus has no access to the
heating circuits for its required minimum runtimes
•
When the design output is less than 70% of the
boiler's rated capacity in wooden houses with low
thermal capacity
•
For above-average hot water needs or high peak
demand (a pellet boiler needs up to 20 minutes
from standby to maximum output and this must
bridged with a buffer)
•
For air heating systems or also individual heating
fans that are started without warm-up time for the
boiler.
•
For integration of a solar heating system with a
low-temperature heating system
At low heating loads,
either install a buffer
or set short heating time slots
For very well-insulated brick walls (not for wooden
construction), the house itself is an excellent thermal
store. If the boiler output is too high, it can be
adjusted to the house's heating requirements by
limiting the heating time to three short time slots
spread over the day.
If there is very low heat consumption during the
transitional period in autumn/spring (e.g. heating
only in the bathroom), then a buffer storage tank is
needed for this low heating load.
For a wooden house with radiator heating, where
there is not even the screed of an underfloor heating
system to act as a thermal store, the installation of
a buffer should be considered. With a design output
less than 70% of the boiler's rated output, an
underfloor heating system operating only with time
slots will cause large temperature variations in the
rooms and a buffer storage tank is required. Heat
produced by the boiler and not currently needed in
the house can be stored in a buffer storage tank and
returned to the heating system when needed.
A sufficiently large hot water tank
To operate the pellets boiler in summer without a
buffer storage tank, a hot water tank with a capacity
of at least 300 litres is needed to take up the heat
from an entire firing cycle. For better convenience,
one should choose a 300-litre tank.