5 x Control unit operation
40
FA ROTEX Solaris - 08/2007
5.2.6 Solaris FlowSensor
The optional Solaris FlowSensor ( 16 41 05) is used to measure flow (V) and feed temperature (T
V
). With the sensor
connected and working:
– the measurement values V and T
V
are displayed.
– after the filling procedure, the control unit works with the actual system temperature difference between feed and return
flow temperatures.
When the system has detected the FlowSensor and if a sensor fault develops, the display shows a corresponding error message
(see Chapter 6.1). The system then works in the emergency mode without the FlowSensor.
No error message is displayed, if the FlowSensor is disabled by the heating technician. The control unit works without the
measurement value V and the feed temperature (T
V
) is assumed to be the same as the solar panel temperature (T
K
).
5.2.7 Output calculation, maximum values and yield count
With an installed FlowSensor, the system calculates and balances the system operating data, e.g. instantaneous heat output,
solar heat yield, etc. Maximum and calculated values can be displayed (see Chapter 5.3). Values greater than 0, which are not
deleted, are still displayed even after disconnecting or disabling the FlowSensor (no updating).
5.2.8 Speed control of circulation pump P1
When all operational conditions have been fulfilled, the Solaris R3 control unit:
– Switches on both pumps with full output up to the max. possible flow.
– Switches off pump P2 when the adjusted minimum running time "Time P2" has elapsed (not in case of booster operation).
– Reduces the output of pump P1 in steps until the difference between feed temperature (T
V
) and return flow temperature (T
V
)
is within the set-value limits (see Fig. 5-2) or until the flow falls below the minimum value V2 (Fig. 5-3).
– Switches the pump to the next output stage after a safety period t
2
has elapsed (Fig. 5-3).
If the pump output is too low, it is possible that the flow in the solar circuit is interrupted. If the flow drops below the value V2
(Fig.5-3) for at least 10 seconds, the control unit detects an interrupted flow and the previously valid pump output stage is stored
as the minimum limit. All lower pump output stages are disabled.
Subsequently, the temperature-dependent control of P1 remains between the determined minimum and maximum output stages.
Hereby, the temperature difference between T
V
and T
R
is measured continuously and compared with the set-value. If the
temperature difference between T
V
and T
R
is too large, the output of pump P1 (max. 10 stages) and therefore the flow through
the solar panel array is increased until the set-value is reached. If the temperature difference is too small, pump output is reduced.
While pump P1 is running, its instantaneous output "Flow" is displayed as a percentage next to the measured flow value.
Fig. 5-2 shows the typical operating curve of a Solaris system with modulated pump control.
The system calculation and balancing functions (e.g. solar heat yield) are no substitute for a calibrated
calorimeter. These values may not be used for invoicing heating costs or similar legally valid accounting
purposes.
TK Solar panel temperature
DT Temperature difference (difference between Solaris feed and
return flow temperature)
S1 Upper set temperature difference ("temperature difference 1")
S1 Lower set temperature difference ("temperature difference 2")
T1 Frost protection temperature ("TR frost")
T2 Booster temperature ("TK max")
T3 Restart inhibit temperature ("TK perm")
— Set value for temperature difference
- - - Switching limits for pump modulation
Fig. 5-2 Pump output control as a function of temperature difference
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