Tekno Training

Impianti intelligenti per un pianeta mig

Tekno Training

Impianti intelligenti per un pianeta mig

The heating system

2021-11-25 09:45:00

Explained in simple words ... for the layman!

How it works and how to avoid calling the technician unnecessarily (Sheet X10.010)

Do you want to know more about your heating system? Are you tired of feeling disoriented and uncomfortable every time the boiler or system has some problem? Would you like to understand if it is really necessary to call a technician or is it something that can be solved independently? Do you feel "ignorant" every time your plumber uses some technical term to illustrate his intervention?

Let's try to explain in simple words how this system works ... so that everyone can better manage the heating of their home, ensuring the correct operation of the system and avoiding unnecessary maintenance!


The heating system, at least in the simplest or standard version, consists of a boiler, distribution manifolds and a certain number of heating bodies (generally radiators). It is practically a "closed circuit", where the water that circulates is always the same (called "technical water"). The circulation pump inside the boiler circulates this technical water from the boiler itself to the distribution manifolds (larger diameter pipes) and from these to the individual radiators (smaller diameter pipes), and then draws the water back into the boiler.

Crossing this "closed circuit" the water is passed into the "main exchanger" inside the boiler (the one represented graphically with a blue and red rectangle). In most cases it is a section of finned and serpentine-shaped tube, although there are different and more complex types.

The exchanger is touched by the flames of the underlying gas burner (assuming a natural gas boiler) and in this way the water is heated. The heat transfer from the flame to the water of the system is facilitated by the presence of "fins" or "blades" which only serve to increase the heat exchange surface.

The so-called "thermostat" or "chronothermostat" is positioned in the most representative room of our home, where we set the desired air temperature (usually the well-being temperature is 20°). When the temperature detected by the thermostat falls below the set value, it is this device that sends the heating system ignition signal to the boiler. By the way... the difference between thermostat and chronothermostat lies in the fact that with the first we can establish a single well-being temperature (example: 20°), while with the second we can set different temperatures at different times of the day (example: 20° during the day and 18° at night).

Therefore, the operation of the heating system can be roughly summarized in the following stages:

  1. The temperature of the room where the thermostat is positioned drops below the value set by us (usually 20°) and the thermostat sends the ignition signal to the electronic board on the boiler.
  2. The electronic board of the boiler ignites the gas burner (assuming a natural gas boiler) and the system circulation pump.
  3. The water taken from the system radiators (blue pipes) is passed through the “main exchanger”, lapped by the flames of the gas burner, and heated until it reaches a suitable temperature (normally 70-75°).
  4. The water heated in this way (70-75 °) is pushed by the circulation pump towards the radiators (red pipes). Over time, the surface of the radiators reaches the same temperature as the water and in this way begins to heat the air in the rooms. This heat transfer results in a cooling of the water at the exit of the radiators (usually 10° less). This means that the temperature of the technical water leaving the boiler is about 70-75° (red pipes), while that returning from the radiators is about 60-65° (blue pipes).
  5. The circulation of water in the heating system, as well as the operation of the gas burner (assuming a natural gas boiler) continues until the room temperature set with the thermostat is reached (for example 20 °). When this temperature is reached, the thermostat sends the block signal to the boiler.


Some simple tips for managing the heating system

The closed circuit of the heating system must logically be filled with water ... the famous "technical water". For the correct operation of the system, the filling of the circuit is carried out through the so-called "filling valve", positioned under the boiler itself, until an optimal pressure is reached (normally 1.5 bar). This loading operation must be performed with the system off. During the operation of the heating system, part of this water can escape from the system itself, for example due to small leaks (usually in correspondence with the connections between the system and the boiler, manifolds or radiators), or due to `` venting operation of the radiators (see next point).

It is important to periodically check the pressure of the heating system, especially at the beginning of the season (September / October), because if the pressure drops below a limit value, the boiler blocks! Therefore, if the boiler does not work, before calling the plumber it is advisable to check the system pressure value and restore it if necessary. Attention ... the pressure value can be read on the so-called "boiler pressure gauge", with a graduated scale in bars, and not on the "boiler thermometer", which instead serves to control the system water temperature and is characterized by a scale graduated in degrees centigrade!

Within the closed circuit of the heating system, air bubbles may form over time. This air tends to accumulate inside the radiators, especially in the highest part of the system on the upper floors (let's not forget that a bubble in a water container tends to rise upwards). Sometimes the air accumulated inside a radiator can be in such quantity as to compromise its performance. How do we know? Just pass your hand over the entire surface of the radiator and check that the temperature is sufficiently uniform: if one part of the radiator is cold compared to the rest (with the system on!), It means that the heating body contains a large amount of air. ! No need to call the plumber ... just bleed the air through the "vent valve" supplied with the radiator. It opens slowly, letting the air out until water begins to flow out. At this point the operation is repeated with all the radiators that have the same problem, then the system pressure is checked using the "boiler pressure gauge": having released a considerable amount of air, the water goes to occupy the spaces that were previously occupied by air and therefore the system pressure must be consequently reduced. Don't worry ... we just have to "load" the system, as explained in the previous point!

If the thermostat or chronothermostat that controls the heating system is powered by batteries, it may happen that the boiler does not start because the batteries are flat and the device is unable to send the ignition signal to the boiler itself. This can happen especially after the summer or a long period of inactivity of the system. So the advice is always the same: before calling the plumber it is good to check the state of the batteries!

These are simple and trivial advice, which cannot and does not want to solve all problems. But ... if we happen to be left in the cold on a winter Sunday (it always happens on a Sunday!), now we may be able to solve the problem by simply charging the system or perhaps replacing the thermostat batteries. The satisfaction would be priceless!!!



N.B. Source of some images: web


by Marco Colmari
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