Typical hydraulics as factory setting

The factory settings are based on the following hydraulic diagram for solar warm water system with a buffer and service water tank, a boiler fired with wood pellets or oil/gas, and two heating circuits:

The assignments of sensors in outputs according to the diagram are based on the special properties of the various inputs and outputs. The following sensors are not used: S8: input for all sensor types or control voltage 0-10V or current 4-20 mA. S15, 16: input for all sensor types including volume flow encoder (pulse input) They are thus available for other functions, such as the heat quantity counter. Outputs with speed control properties were assigned to the solar and load pumps to ensure that any PID function blocks can be switched.

The diagram above has the following desired functions:

A SOLAR CONTROL from S1 > S3 A1 and another one from S1 > S4 A2
SOLAR PRIORITY, with S1 > S3 A1 having priority over S1 > S4 A2
TWO HEATING CIRCUIT CONTROLS with S10, S12, S13 A3, A8, A9 and S11, S12, S14 A4, A10, A11, and the two flow nominal temperatures ANALOG MODULE Requirement warm water with S2 ANALOG MODULE REQUIREMENT HEATING based on a greater flow nominal temperature in both heating circuits and the effective nominal temperature of the REQUIREMENT WARM WATER compared to the tank temperature of S7 A5 Three LOAD PUMPS with S9, S5 A6 and S9, S2 A7 and S7, S2 A7 - an additional service water load is thus possible from the buffer and the boiler.

The „REQUIREMENT HEATING“ shows that the ANALOG FUNCTION (MAX = look for the highest temperature in the input variables) is required to determine the greater flow nominal temperature of the two heating circuits and the effective nominal warm water temperature. The two heating circuit pumps A3 and A4 should not be released unless the temperature in the boiler or the buffer is high enough. Therefore, a COMPARATIVE FUNCTION is needed at boiler sensor S9 and buffer sensor S7. They are designed as simple thermostat functions (= compare the sensor to an adjustable temperature). However, it is also possible to use the compare function of buffer sensor S7 to compare the sensor with the flow nominal temperature of the respective heating control unit via two separate comparison functions. Only one input variable is available to enable the heating circuit pumps in the respective function. However, as the temperature in either the boiler or the buffer has to be high enough and this information is gathered from two functions (comparison), the information has to be gleaned via the LOGIC FUNCTION (output variable = input variable 1 or 2).

In other words, the following functions are added:

ANALOG FUNCTION (MAX) with two flow nominal temperatures and the effective nominal warm water temperature as an input variable and the result heater requirement (nominal value for the temperature comparison) Two COMPARISON FUNCTIONS with S7 and S9 logic function A LOGIC FUNCTION (OR) with the comparison functions and input variable and the result heater regulator 1 and 2 (Enable pump). If S7 is divided up across two comparison functions as described in a comment above, separate logic functions are required for the two heating circuits.

If the system that is planned only deviates slightly from the one described here, the functions not needed should be deleted (such as only one heating circuit) or the functions should be changed (such as for a warm water system with a pump / valve system) or new functions added (such as an additional boiler fired by solid fuel). If the differences are great, it makes most sense to delete all of the functions and then start a new function list with new parameters.