A malfunction of the boiler can seriously affect the supply of domestic hot water or the activation of the heating system. Often the malfunctions may seem unusual; they may in fact depend on factors or events that have nothing to do with the boiler itself: this is the case, for example, of the lack of gas supply, of a malfunctioning tap ...
Boiler block: what are the most common causes?
Accumulation of limescale
Limestone is generally the main cause of the lack of hot water supply; the micro limestone debris accumulates behind the filters in correspondence with the dispensers; consequently there is a reduction in the water flow such as not to allow the boiler to activate.
Another cause could be the interruption of the gas. In this regard, you must make sure that one of the kitchen stoves lights up. If there is no gas, the causes could be different.
There may be some work on the conduct by the supplier, in which case you can consult the provider company. The lack of gas could also be due to the gas valve that feeds the boiler; it may be damaged or blocked. In both cases there is no do-it-yourself intervention, you need to consult a technician.
Damage to the electrical system
Another blockage of the boiler can be caused by the lack of electricity or by damage to the electrical system. In the latter case, the system that generates the spark that starts the pilot flame may have been damaged: the two electrodes may have oxidized.
In some old models of boilers, the electricity that activates the electrodes is given by a battery that may have run out.
The latest generation boilers are equipped with a display that indicates in real time the status of the boiler; if the boiler should lock up, an abbreviation on the display would indicate the probable problem: to verify the cause, simply decode the abbreviation from the instruction booklet of the boiler itself.
Some lockout states can be reset, just reactivate the boiler, other models require the intervention of competent technicians.
Boiler block, do-it-yourself checks
Among the checks that can be performed without the intervention of the technician we have: power supply; fuel supply, water availability, water pressure value which corresponds to 1.5 bar.
Low pressure boiler block
On each boiler there is a pressure gauge which indicates the pressure which must be between 1.5 and 2 bar. If the pressure drops below 1.5 bar, the boiler blocks; in this case it is possible to restore it very easily by acting on the adjustment tap. But be careful not to go beyond the suggested value: if too much water is allowed in, the pressure will go above 2 bar.
To decrease the pressure it will be sufficient to open the vent of a radiator, in which case you will need to equip yourself with a container to collect the water.
Air in the radiators
Even in the case of excessive air in the radiators there is a malfunction of the heating. In this case it will be necessary to remove the excess air: it will be sufficient to open the vent of each radiator and leave it open until all the air has escaped. Along with the air, water will also come out so, even in this case, it is advisable to have a container to be placed under the breather. Once the operation is complete, double-check the water pressure which may have dropped below the minimum threshold.
Insufficient exhaust gas draft
The blockage could also be caused by a lack of correct exhaust gas draft: if the fumes are not expelled correctly, a special sensor prevents the system from functioning. To restore it, check the flue gas exhaust system, clean it and, if necessary, unblock it from dirt.
Boiler block, technician intervention
It may happen that a technician replaces one or more boards before identifying the cause of the fault. In this case it is your right to ask, at the end of the work, to reassemble the replaced boards: in this way you will avoid a greater outlay of money if they are not damaged!
For further information, we recommend reading the article "Boiler repair, how to do it"