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Hydraulic balancing with intelligent control valves for daycare centre

Artificial intelligence in control engineering

The St. Ulrich children’s day care center of Burgberg in Germany's Allgau region

contains an intelligent underfloor heating system circuit regulation system with self-learning control valves.

The same problem every year:  The St. Ulrich children’s day care center in Burgberg calls up Herz & Wesch GmbH promptly at the beginning of the heating season and complains about the non-functioning underfloor heating system.  The day care center consists of a mixed complex divided into an old and a new section. Both parts of the building are supplied by a joint central heating system - just not in a way they would prefer. Neither building section had so far had an individual room control system, but rather only manual adjustment knobs on the distributor which people used to even out the poorly heated areas with the strongly heated areas.

In addition, Herz & Wesch GmbH detected substantial flow volume problems in several circuits. Manual hydraulic balancing using the flow volume meter proved to be extremely difficult due to the missing flow diagrams and therefore unknown pipe lengths of the individual heating circuits. A worrisome initial situation which normally requires extensive calculations which still only yield an estimated result.

TECHNICAL DEVELOPMENTS LEAVE MUCH TO BE DESIRED
The principle of a heated surface is at least as old as our modern calendar. Heating a floor is however still a problem occupying many minds today, and the control and balancing of these systems is still a very critical topic. The goal is to find all possible sources of error and implement a new underfloor heating system which outshines all that have come before. These requirements, in short, necessitate an automatic hydraulic balancing system and a requirements-based regulation of the heated surface.  There is, however, a huge gap between theory and practice here.

The technical progress of the last 20 years, with product innovations such as the flow volume controller and recently the "flow volume-constant valve" have unfortunately not brought any real satisfactory solution. These new valves are certainly simple and quick in installation, however they require exhaustive manual calibration on the basis of planning calculations.   Even with modern technology, these settings are time-consuming, require specialist personnel, and place a burden of liability on the tradesman doing the implementation. An additional weak point: Today's control drives only recognize two states (open/closed), and the calculations for the flow volume are based on the worst case. Therefore, in 99% of all cases, the set flow volume on the yearly average is much too high.  In addition, most underfloor heating systems are calibrated only once: during initial installation. Adaptations to room uses which have changed over the years or even to structural modifications (e.g. room divisions) are seldom made.  Seen objectively, the hydraulic balancing of today's systems is neither easy nor convenient for the tradesman, nor does it meet our requirements for energy efficiency.


RECOGNIZING AND ELIMINATING WEAK POINTS
A hydraulic balancing solution for the next generation should in essence meet the following three criteria: 

  1. Time saving and convenience during installation as well as absolute certainty of a correct hydraulic balance for the tradesman
  2. Improvement of the energy efficiency of the entire system
  3. Absolute mass market suitability through manufacturer-independent compatibility with all systems

The "EGO" control valve steps up as the problem solver here. With its infeed and return sensors, it records the temperature differences constantly, and, thanks to its artificial intelligence, it also adapts the flow volume continuously. Hydraulic balancing is therefore not just performed in the design phase, but rather for all intermediate loads. EGO optimally controls the flow volumes variably between 0.2 and 3 l/min. To avoid contamination of the valve for low valve openings, the control valve opens the valve completely for one time at regular time increments in order to flush it. A temperature monitoring function monitors each circuit and closes the valve when the infeed temperature is greater than 60 degrees, which is indicated by a red LED.

REQUIREMENTS-BASED CONTROL AND OPTIMAL ADAPTATION TO THE ROOM USAGE
After the system is installed , the "EGOs" perform a resilient hydraulic balancing at the site. The new control valves therefore completely eliminate the human error factor in heating circuit regulation. Sensors on the lines measure temperate differences – the rest is performed, in accordance with manufacturer specifications, by Al and the microchip through calculation of the correct temperature difference and the associated valve setting.  

And this is done not only upon commissioning, but rather continuously. On the basis of constantly available measurement values, the EGO-Kl recognizes the system environment independently, learns the usage behavior of the residents and adapts the entire underfloor heating system, even after a change in room usage after years or after structural changes.

The installation is as easy as can be and differs for conventional control valves only in one small matter – simply inserting the clip, which is already pre-installed and fits all standard pipe diameters, attaches the temperature sensor to the infeed and return pipes. You need neither a special commissioning nor a parameterization, nor additional components such as a router, gateways, or an app control system. This is a substantial difference from the "home automation systems" currently on the market.

For these reasons, EGO control valves only were installed as plug-and-play solutions on each individual heating circuit in the St. Ulrich day care center. EGO can be used here on all standard distribution systems. In addition, each room receives its own room thermostat so that the desired room temperatures can be set everywhere. The children of the day care center can look forward to a cozy rest of the winter with even heat distribution throughout the entire building.

As part of the new strawa data records for home stations, the EGO control valve will also be available in the future in the liNear software.

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