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[Buffer] function block Configuration parameter
Explanation of [Flow temp raise]
The target temperature of the buffer [Buffer target] is
increased by this value when the buffer is demanding
heat from the boiler.
This ensures that the boiler temperature is sufficient
for reaching the target temperature in the upper
section of the buffer. As long as the boiler has not
reached the target temperature [Boiler tgt.], the boiler
is operated in the high-output range.
Example:
[Buffer target] = 70 °C
[Flow temp raise] = 5 °C
=> The accumulator tank demands 75 °C from the
boiler. The boiler target temperature is therefore 75°C.
Explanation of [Enable temperature]
This parameter defines the minimum temperature of
the boiler for charging the buffer. Buffer charging can
only occur when the boiler has exceeded this tempera-
ture.
Explanation of [Chrg. at buffer top/middle] and
[Chrg.at buffer middle]
The additional [Buffer top/middle] and [Buffer middle]
temperature sensors enable the boiler to be started
earlier, in order to charge the buffer. The two functions
[Chrg. at buffer top/middle] and [Chrg.at buffer middle]
are available for this purpose.
If you set the function [Chrg. at buffer top/middle] to
[Yes], buffer charging starts as soon as the [Buffer top/
middle] temperature sensor drops below the buffer
target temperature [Buffer target].
The function [Chrg.at buffer middle] has the same
effect if the [Buffer middle] temperature sensor
drops below the target temperature.
However, this causes the boiler to fire up more
frequently.
CAUTION!
Do not set functions [Chrg.at buffer middle] and
[Switch off at buffer middle] to [Yes] at the same
time.
Otherwise, the boiler will be switched continuously on
and off.
Explanation of [Switch off at buffer middle] and
[Switch off at buffer middle/bottom]
The additional [Buffer middle] and [Buffer middle/
bottom] temperature sensors enable buffer charging
by the boiler to be stopped early. The two functions
[Switch off at buffer middle] and [Switch off at buffer
middle/bottom] are available for this purpose.
If you set the function [Switch off at buffer middle] to
[Yes], buffer charging stops as soon as the [Buffer
middle] temperature sensor reaches the configurable
switch-off temperature [Buffer bottom off].
The function [Switch off at buffer middle/bottom]
has the same effect when the [Buffer middle/
bottom] temperature sensor reaches the configurable
switch-off temperature.
These functions reduce the buffer volume to be
charged. This makes sense if a solar heating
system that charges the buffer lower section is
connected to the buffer, for example.
CAUTION!
Do not set functions [Chrg.at buffer middle] and
[Switch off at buffer middle] to [Yes] at the same
time.
Otherwise, the boiler will be switched continuously on
and off.
Explanation of [Buffer bottom off]
This parameter ends charging of the buffer storage
tank by the boiler. As soon as the [Buffer bottom]
temperature sensor in the buffer storage tank has
exceeded the configured [Buffer bottom off] tempera-
ture, charging of the buffer by the boiler is stopped.
The factory setting for this parameter is 40°C.
The value should be at least 5 - 10°C above the
average return temperature of the consumers, but no
more than 70°C.
A high [Buffer bottom off] temperature reduces the
number of boiler starts and improves boiler running
time.
Explanation of [Enable difference]
This parameter is only active when the buffer
absorbs the residual heat from the boiler after a
heating period.
The boiler temperature must be higher than the [Buffer
bottom] temperature by this value in order for the boiler
pump or buffer charging pump to switch on.
Explanation of [Effective buffer volume [l]]
The effective buffer volume is the buffer volume from
the highest point of the buffer to the height of the return
connection to the boiler.
If several buffers are connected in series, the
effective volume of each individual buffer is
added together and the total volume entered in the
control system.
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