The drive towards a more economical use of energy resources leads to the following measures:
1. optimising the supply of heat to living spaces, meaning that a well-designed system heats the rooms in use for a period limited as closely as possible to the time when the space is actually occupied
2. better and healthier use of heat, with a lower temperature of the medium entering the heated space
In practice, this means building:
1. heating systems that, with the greatest possible independence of control, can meet the requirements of a defined heated space, which leads to heating systems being divided into zones ever more frequently
2. systems with a low medium temperature (or, more often, mixed systems)
This practice increasingly shows that the new direction of technological development in heating engineering, apart from the development of the heat sources (boilers) themselves, will lead to an ever more thorough redesign of the subsystems involved in the operation of the heating system.
By service subsystems we mean the mechanical, hydraulic and electronic equipment that ensures the correct pressure drop, the correct control behaviour and safety on the basis of measured values of the relevant variables, from signal conversion through to the triggering of the control elements – in other words sensors, valves and electromechanical actuators, all controlled through an ever more sophisticated electronic interface.
It should be stressed here that integrated control of the heat generation system is part of the comprehensive management of all the building services in a home and represents a new way of designing living spaces: the installation is no longer a "foreign" element in the flat, but becomes a harmonious part of the household.
All the equipment that used to be assembled on site, such as manifolds, pumps, valves and electrical wiring, is now – thanks to proven and established solutions such as relay control – gradually being replaced by assemblies supplied by the boiler manufacturer, which offer the following advantages:
1. they are specifically developed to ensure the optimum connection to a particular appliance, guaranteeing the best performance and fuller use of that appliance's capabilities
2. they make installation considerably simpler
3. they greatly reduce the sizing work for the installation components
It can safely be said that the future of heating installations is moving more and more towards modularity. Examples can be seen both in central heating and in independent systems.
In the first case, there is growing use of modular systems, which give the designer and the installer the option of matching the system's output to the needs of the building by combining heat generation "packages" in the required quantity.
Such equivalent modules have the advantage of adaptability, and practically all the mechanical and electronic components needed for their correct and safe operation are housed inside them. In these cases, installation is limited to connecting the appliance to the hydraulic connections and the flue system.
In independent installations, on the other hand, we are seeing the progressive integration of traditional manifolds, circulation pumps and valves, which are electronically controlled and built into compact units. In the past all of this equipment needed its own installation space, because it was bulky and unattractive. Today, integrated distribution assemblies are used (for example the Immergas DIM zone hydraulic manifold).
These modular assemblies have a very precisely engineered interface for connection to the boiler, as the following diagram illustrates.
The two electronic control systems communicate and jointly manage the entire heat distribution according to the required times, circuits and temperatures.
It can be said that units interconnected in this way represent genuine "software"; that is, the thinking heart of the heating system.
This is the exact opposite of the current legislative concept of a "distribution system"; which is understood from a physical and thermodynamic point of view as a single entity from which heat is simply released. Such an approach is too simplistic.
On the other hand, this point of view calls for a radical revision of both the basic concept of the system and the calculation methodology.
The efficiency of a system conceived in this way, and the effect of the interaction between the heat source and the heat flow control system, call for analysis and detailed investigation on site. Their mutual influence needs to be assessed synergistically, not separately as current legislation prescribes.
Such an assessment requires test equipment and, of course, a test protocol that would make it possible to simulate the operation of the system under conditions as close as possible to real ones. In this context the design engineer becomes the central figure, because simulations could reveal certain phenomena relevant to a realistic assessment of the heating system's properties. We believe that this could be the springboard and the material for future legislation on calculating the properties of heating systems – and that future is hopefully not far off.