Overview Solar 1 Boiler/Buffer



This function block realizes a solar control with one solar circuit and switching between boiler and buffer. Via a switchover valve, the solar yield is charged into either the boiler or the buffer.

If the solar temperature is higher than the temperature of the respective storage tank by the Hysteresis solar on and its temperature is below its maximum, the valve switches to this storage tank and the pump turns on:
  • Without Boiler priority, the storage tank whose switch-on condition is met first is charged.
  • With Boiler priority, the boiler is charged first; only once it has reached its Boiler maximum does the valve (VP = 1) switch over to the buffer.
With the pump switched on, the speed is controlled via a P controller (Gain) so that the temperature of the active storage tank (boiler or buffer) is held as setpoint; the result is present at the output Pump analog 0-100%. The pump is switched off when the difference falls below the Hysteresis solar off or the solar, boiler or buffer temperature reaches its maximum value.


Inputs

BO Temp. boiler Temperature boiler.
PU
 Temp. buffer
 Temperature buffer.
SO
 Temp. solar
 Temperature solar (collector).

Outputs
PU
 Pump digital
 Pump digital on/off.
PA
 Pump analog 0-100%
 Pump analog. As an alternative to control via switching hysteresis, a pump with analog control can be used at this output.
VP Valve buffer Valve switchover boiler/buffer: 1 = buffer, 0 = boiler.

Parameters
Solar maximum
 Maximum temperature solar. If the temperature exceeds this value, the pump is switched off even if the storage tank temperature has not been reached.
Boiler maximum Switch-off temperature boiler. If the boiler temperature exceeds this value, boiler charging is ended.
Buffer maximum Switch-off temperature buffer. If the buffer temperature exceeds this value, buffer charging is ended.
Hysteresis solar on
 Difference between solar and storage tank at which the control becomes active.
Hysteresis solar off
 Difference between solar and storage tank at which the control becomes inactive.
Gain Control setting; the higher the value, the faster the analog output changes with a change in temperature.
Boiler priority If this parameter is active, the boiler is charged first. Only once the boiler maximum is reached is switching to buffer charging performed.

See also common parameters of all function blocks.