25Operating and Installation Manual for Solar Module VR 68 0020054784_00
Glossary
Deactivation difference
The deactivation difference is the difference between
the collector temperature and the storage temperature
at which the solar pump switches off, thus stopping the
transfer of solar heat to the solar cylinder. With Vaillant
controllers, the deactivation difference can be adjusted
within a specific range.
Caution: The deactivation difference must be at least 1 K
smaller than the set activation difference!
Activation duration controlling
ED controlling is the abbreviation used for activation
duration controlling in solar controllers. Activation
duration controlling serves to keep the solar circuit at
the activation value, and thus in operation, for as long
as possible. To achieve this, periodic impulses are
provided by the solar pump by switching it on and off
with reference to the difference between the
temperature of the collector and temperature at the
bottom of the cylinder. Once the activation difference is
reached, the function is started (if activated) with 30 %
of the activation duration, i.e. the solar pump is switched
on for 18 s then switched off for 42 s. The activation
duration increases as the temperature differential
increases. Activation duration controlling is activated at
the installer level.
Activation difference
The activation difference is the difference between the
collector temperature and the storage temperature
when the solar pump switches on and starts transferring
solar heat to the solar storage tank.
Holiday function
If the VR 68 is operated in holiday mode, the solar yield
and reheating functions are deactivated for the specified
holiday period. The storage temperature is controlled
automatically via the frost protection function.
Anti-legionella function
The temperatures in solar cylinders are frequently low
for longer periods – this encourages the growth of
germs (e.g. legionella). The legionella protection function
can be activated one day a week only or every day at a
specific time to prevent legionella multiplying. The
legionella protection function ensures that the solar hot
water cylinder is heated to a temperature higher than
60 °C for one hour. The circulation pump and legionella
protection pump are activated via the anti-legionella
function in order to ensure that the entire contents of
the cylinder and the circulation system are heated. The
function is deactivated after 2 hours at the most, even if
a temperature of more than 60 °C was not achieved.
Maximum temperature of solar storage tank
In order to obtain the maximum yield from heating the
cylinder with solar energy while at the same time
providing the option of protection from scalding and
calcification, you can set a maximum limit for the solar
cylinder temperature.
For this purpose, the sensor "upper cylinder temp." SP1
is used for storage tank 1 if it is connected to the storage
tank in question. Otherwise, the sensor "lower storage
tank temp." SP2 is automatically used. For the second
cylinder (swimming pool) SP3 is used.
If this maximum temperature specified is exceeded,
the solar pump is switched off. Solar heating is only
reactivated when the temperature at the active sensor
falls back to 1.5 K below the maximum temperature.
The maximum temperature can be set separately for
each sensor.
Tube collector function
see solar pump kick function
Solar yield
The solar yield is determined from the following:
– the difference between the collector feed and return
temperatures,
– the flow rate set at the control valve of the flow rate
limiter (value is set during installation),
– the running time of the solar pump.
The expert technician adjusts the flow rate limiter during
the installation and enters the flow rate in the
installation assistant.
The total solar yield is calculated by the solar controller
and can be called up or reset at the operation level for
the operator.
Solar circuit safeguard
If the solar heat supplied exceeds the current heat
demand the temperature in the collector increases
rapidly which results in the formation of vapour bubbles
in the system (stagnation).
If the collector temperature exceeds the temperature
protection value (130 °C) for more than 10 seconds
(default setting), the solar pump switches off. This
protects the components of the solar circuit from
overheating. The solar pump switches back on
automatically as soon as the collector temperature
falls to 30 °C below the switch-off temperature.
Solar pump kick function (tube collector function)
The solar pump kick function is only activated if tube
collectors are used.
Depending on the design, there may be a delay when
recording the actual temperature of tube collectors. This
can be reduced using the solar pump kick function.
When the temperature at the collector sensor rises by
2 °C, the solar pump is switched on for 15 s (solar pump
kick). This transports the heated solar fluid faster to the
point of measurement.
Glossary
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