Strange noises, similar to a whistle or a metallic sound rather than a bang: these are signs that the boiler has a problem that needs to be dealt with immediately. This situation can in fact lead to a lockout or get worse, making it unusable.


When should I worry about the boiler?


Making sure that the boiler works correctly is very important both to keep it in good condition and for the safety of the people living in the house. It is therefore necessary to pay attention when the boiler makes any unusual and strange noise.

The strange noises that a boiler makes when the hot water is turned on are mainly:

  • metallic noise;
  • thud or popping noise;
  • whistle;
  • gurgling.

Depending on the type of sound, the cause may be different and requires the assistance of a specialised technician to be resolved.

  • Metallic noise. It comes from the boiler and can be heard more frequently, especially when it is turned on. It can derive from the fan or a tool to expel the combustion fumes.
    Over time the fan may loosen or be damaged. When active, it ends up touching other components of the heat generator, causing a metallic noise. The stalling of the fan leads to the bolier’s lockout, with all the resulting inconveniences.

  • Dull noise. It is emitted when the boiler starts up and at that moment it makes a bang similar to a bursting noise. It is generated by the flame which is lit inside the boiler for the production of domestic hot water.
    It happens if the operation does not take place correctly: there is probably a bad regulation of the mixture of combustible gas and air needed for ignition. It is therefore easy to understand how this unexpected event requires timely intervention.

  • Whistle. It is related to gas flow. If it is too low or at minimum, the boiler will make a hissing noise when reducing the burner rpm. The gas nozzle needs to be adjusted.

  • Gurgling. The reason for this unusual noise is most likely due to a problem with the primary heat exchanger.
    It could be blocked by limescale, an inconvenience that often occurs with older boilers and on which correct maintenance has not been carried out. As in other cases, the intervention of a specialised technician is necessary for a thorough chemical cleaning or for the replacement of the heat exchanger.

Why is the condensing boiler making noise?


Even condensing boilers, which belong to a more technologically advanced generation, can make strange noises, just like traditional ones.

The reason is to be found, for example, in the limestone inside them and on the heat exchanger. Another hypothesis concerns the excessive speed of the water flowing.

A particular situation is the one in which the boiler starts making noise with the hot water running from the tap. It is an indication that one of the components of the generator has a malfunction. The use of domestic hot water activates the boiler and its elements: the heater, the burner, the pump and the fan.

Pressure also comes into play, with the presence of air bubbles which prevent the normal and regular functioning of the boiler.

Considering the many factors involved, the skills of a professional expert are the best solution to adopt.



Why is the boiler making noise with the radiators on?


A frequent question from users is: “Why does the boiler make noise when I turn on the heating system?”.

The boiler has a double function: it produces domestic hot water and it lets the radiators warm up. The answer to the question is therefore to be found in some boiler malfunction.

In most cases there is the complicity of scale deposits on the primary exchanger. Limestone is particularly invasive in areas where the water is hard due to the high mineral content, including magnesium and calcium. At high temperatures they generate calcium carbonate, or limestone.

To remedy and solve the setback, the heating system must be cleaned with special products. Washing the system with these restorative and protective substances favours the removal of incrustations and deposits.

To preserve the boiler from further hitches, a specific treatment of the system is recommended, directly on the water inside it with chemical additives or with an anti-limescale filter.



How to fix a noisy boiler


Any interventions to eliminate the noise from the boiler must be carried out by a specialised technician. In fact, the experience of a professional is needed to identify the origin of the sound before continuing and working on the system.

If the problem is not addressed properly, the boiler can go into lockout. It means it stops working, leaving your home without heat and hot water, and a simple reset is not enough to fix the problem.

Accurate maintenance of the heat generator helps to preserve it from hitches and nasty surprises that favour annoying setbacks and inconveniences. Also in this case, the assistance of the specialised service is always the most efficient solution.

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