Open and closed-loop heating control

To keep the rooms cosy and warm, a well-functioning heat circuit is essential even when there is hail and snow outside. As you know, this circuit is formed by the heat generator, the heating pump, the heating pipes, the radiators and various safety-critical components such as expansion vessels and safety valves. All this is combined with the system technology featuring open and closed-loop control functions which ensure that all components interact perfectly and deliver heat to the rooms via the radiators or heating surfaces in an effectively metered and reliable manner.

Open and closed-loop control – what's the difference?

The two terms "open-loop heating control" and "closed-loop heating control" are often abbreviated to "heating control", as if the two terms were interchangeable. But there is a small but subtle difference between the two.

Open-loop heating control refers to the processing of an input variable in order to achieve a target variable. In other words, the open-loop heating control ensures that the heat generator switches on (automatically) as soon as the input variable, for example the outside temperature, falls below a certain value. In this case, the heat generator provides heating energy until the target variable, for example 21 degrees Celsius in the living room, is reached.

Compared to open-loop heating control, closed-loop heating control goes one step further. It doesn't just process an input variable to achieve a target variable. It also monitors the achievement of this target variable. It does this by measuring the current temperature in a reference room and comparing it with the target variable. If the two values differ, an instruction is given and executed, thereby ensuring that the actual value corresponds to the target value. Closed-loop heating control also takes into account interference factors such as open windows, additional heat from solar radiation and the presence of people.


Combination of open and closed-loop heating control

In practice, the whole heating process is somewhat more complex. For example, not just one, but several control units are installed in or connected to a Viessmann boiler to process the information. In the case of advanced heating systems, therefore, experts speak of a combination of open and closed-loop heating control. This is the only way of ensuring that the target variable is not only achieved safely, but also economically and in a technically efficient way.

If the outside temperature sensor is defective or there is a fault in the heating system control, a heating contractor should be contacted immediately due to the complexity of the closed-loop control system.

Closed-loop heating control from Viessmann

"Power is nothing without control", according to a famous advertising slogan. We can also interpret this accordingly as meaning that only the open and closed-loop control system makes a product what it is: an intelligently conceived end result. Viessmann's Vitotronic closed-loop control system with communication capability is the beating heart of every heat generator. Whether we're talking small boilers, wall mounted boilers, medium sized and industrial/commercial boilers, or heat pumps, there is a suitable Vitotronic version for every system. The open and closed-loop control system ensures economical and safe operation and is also very user friendly. Menu guidance is intuitive whilst operating convenience is exceptionally high.

The most convenient way of controlling a heating system is with a remote control. Viessmann has developed several models for this purpose. They can control one or more heating circuits, depending on the type. Simultaneous open-loop control of up to four boilers (cascade control) is also possible. Important functions such as the display of all relevant information are pre-installed in all models and available ex works.

For even greater convenience, the Viessmann heating system can be controlled via an app. This requires an interface such as Vitoconnect, a web-enabled mobile device such as a smartphone or tablet, and the Viessmann ViCare app. If all requirements are met, heating system owners can even control their systems while on the move, for example, to adjust the temperature or change the switching times. They also have the option of contacting their heating contractor with a single tap of the screen. It is also possible to use a combination of remote control and app. Detailed information on this subject can be found on the Viessmann apps page.

Many heating systems are weather-compensated. This means that the heat generator adjusts the flow temperature depending on the outside temperature. Once the system has been adjusted and customised by the heating contractor, system owners can sit back and enjoy the heating convenience.

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