Efficient control

The system can be controlled according to two principles: a set-point system, where the flow temperature is set regardless of external conditions and a climatic system, where the flow temperature is constantly adjusted to the external temperature. Control units of the near future will be advanced control systems capable of optimising consumption as a function of comfort using the PID algorithm.

Set-point temperature control

A set-point system is the most simple way to control temperature. It guarantees the system a constant fluid flow temperature.

The value is set manually via a thermostatic valve. The compact size of this type of control unit means it can be housed in a box connected directly to the manifold - a feature that facilitated its widespread use in the past.

The major limitation is that the user has to adjust the system every time the external conditions change. To reduce the need to do this, the practice has become to calibrate the thermostatic valve to the design temperature (equal to the maximum temperature necessary on the coldest day of winter) and to install thermostatically-controlled electrothermic actuators on the system.

The thermostat compares the temperature set by the user with the temperature of the room. If the temperature in the room exceeds the temperature set by the user it disconnects the power to the actuator which closes the circuit(s). All actuators are equipped with an auxiliary microswitch which allows the circulation pump to be turned off when all circuits are closed, without the need to add link modules.

In the case of a single temperature-controlled room, the room thermostat can be connected to the pump supply. When the set temperature is reached, the fluid flow in all of the manifold circuits is stopped. In these types of systems, the characteristics of the thermostat are of particular importance.

If the room thermostat detects a temperature above the set temperature, it means the screed and fluid are at a higher temperature than necessary. If this happens, the excess heat of the screed will have to be dumped while continuing to provide heat to the room. However, this will not prevent the room temperature from continuing to rise and hours may pass before the screed cools down sufficiently to reduce the temperature of the room.

When the temperature of the room has dropped to below the set temperature, the thermostat will reopen the circuits to allow the screed and fluid to heat up until the room is again at the ideal temperature.

In a set-point control system, the water circulates at a temperature that corresponds
to the value required for the coldest day of winter.

In summary, the room‘s temperature will continually oscillate. The greater the difference between the required water flow temperature and the temperature of the water actually circulating in the system, the more noticeable the phenomenon. This means that the temperature set on the thermostatic valve must not be too high. To minimise the oscillation effect, it is important to select a thermostat with a small differential, although the best solution would be to use a proportional thermostat, such as the built-in Evo thermostat.

This particular thermostat is a modulating thermostat rather than an on/off thermostat. Within a differential of 1.5°C, the thermostat opens the valve for a period of time proportional to the difference in temperature between the value set and the value recorded. This means that as the desired temperature is reached, the amount of heat supplied is progressively reduced, with the effect of reducing temperature oscillation in the room.

Climatic temperature control

A climatic control system is the more efficient way of controlling temperature and offers the greater energy savings.

The amount of heat required to maintain conditions of comfort in a room is linked to external temperature and a building‘s heat loss. Heat requirements increase with decreasing external temperatures and increasing building heat loss. A climatic control system allows you to select a heating curve from among a set of curves, allowing the settings to be adjusted to the specific building.

Once the heating curve has been set, the flow temperature to the system is regulated automatically according to external temperature, adjusting the heat input to the heat demand of the building and thereby ensure continued optimum comfort.

The system does this using a digital electronic control unit to which two temperature probes are connected - one to measure external temperature and one to measure the system flow temperature - and a servomotor. which drives the mixer valve.

The control unit processes the signal from the external probe and, based on the climate code that most suits the building type, determines the ideal value for the flow temperature, comparing it with the actual value measured by the supply probe and, if necessary, operating the mixer valve.

Climatic control adjusts the flow temperature based on heat required.

Climate according to building:
The slope for flow temperature depends on the heat requirements of the building!

The climatic curve or heating curve is the relationship between the external temperature and the flow temperature to the heating bodies calculated by the climatic regulators. Two parameters are required to scale the curve correctly:

  • Minimum external design temperature, for example Milan -5°C
  • Maximum flow temperature to the floor system, for example 40°C floor system

Knowing these values allows us to link the two corresponding lines on the graph, thus producing the curve.

PID: advanced climate control

Advanced climatic control system for optimal management of indoor comfort, from heating in winter to cooling in summer, including air renewal and humidity control.

For a device to keep a certain value constant, such as a speed, temperature, level or route etc., it needs a regulator. Something to correct eventual and inevitable fluctuations from the desired value.

If we think of the automatic pilot of a ship which has to maintain a chosen course, it is easy to understand how wind, currents and waves are sources of error which the regulator has to counter. If we set a temperature in a room, the regulator must be able to correct errors due to internal and external environmental changes such as variations in heat loss to the outside, variations in heat gain due to radiation at the different hours of the day, or internal losses or gains due to the presence of people and the switching on of electrical equipment.

Since every room is unique in its characteristics and energy needs, the control unit must be able to recognise the area with the greater need, automatically setting the system parameters to meet it. In addition, as climatic conditions change, the unit must redefine the problem area in real time.

This allows the unit to manage indoor comfort in both winter and summer and air renewal and humidity control.

This optimised management of comfort is made possible by a proportional-integral-derivative control system, or more simply "PID" - the most efficient system available for controlling room temperature.

The PID controller regulates the system on the basis of 3 inputs:

  • Proportional action: the value for room temperature at that point in time
  • Integral action: past values for room temperature
  • Derivative action: prediction of variation of room temperature

The advanced control system is able to select the most suitable water temperature based on external temperatures and building characteristics. Finally, to ensure comfort when the user wants it, the unit starts and stops the system according to whether movement is detected in the room. In doing so, the set temperature is reached exactly when needed, reducing unnecessary energy consumption and any drop in comfort levels.

Monthly primary energy consumption

Monthly expenditure