The right level of water pressure ensures proper functioning of the boiler. In fact, if it is too low or too high, there is a real risk that the boiler will shut down and that the heating system will not work. Monitoring the pressure trend is therefore very important.

What happens if the boiler exceeds 2 bar?

To avoid cold or running out of hot water, it is essential to pay attention to any anomalies that arise in the home boiler. Among the elements to keep an eye on is undoubtedly the pressure level, with the help of the manometer, the tool that indicates the bar value.

First of all, it must be remembered that the ideal pressure for a boiler is between 1.2 and 1.5 bar. However, it may happen that the pressure value goes beyond the indicated limits and that the pressure is too high or too low.

• If the pressure is too low, the boiler risks going into lockout. This happens because the safety system inside the heat generator detects an anomaly and therefore does not allow regular ignition. The lowering of the boiler pressure can be caused by a water leak, excessive air, natural evaporation of the water, deterioration of the expansion tank or the first seasonal ignition. 

• Similarly, if the pressure is too high, the boiler may have problems that can compromise its use, including the heating system lockout. The mishap can be caused by too much air or water. In particular, in the case of a pressure level that exceeds the maximum limit of 2 bar, it is possible to intervene by venting the radiators. In this way, the excessive air that prevents the normal flow of water is eliminated. To find the radiator on which to intervene, it must be checked which of those present in the house is only partially heated.

On the other hand, the solution may not be that simple or obvious. It is therefore a good thing to rely on the skills of a specialised technician and have the boiler subjected to periodic maintenance checks.

In fact, it may be necessary to act on the expansion vessel, a metal container that absorbs the desired increase in water, guaranteeing system stability. If it is deflated, there is more air than water inside it and the correct pressure must therefore be re-established.

What should boiler pressure be when the heating is off?

The range between 1.2 and 1.5 bar must be valid in any situation, both with the boiler on and in summer, when its use is limited.

If the boiler does not work for longer periods, the pressure could drop below the value of 1.2 bar. To increase the pressure, it is necessary to act on the filling loop, allowing more water to enter the circuit.

The tap is generally placed at the bottom of the boiler. Once opened, the pressure should quickly rise again to the minimum indicated. However, as previously mentioned, the excessive lowering of pressure is also linked to other factors and only qualified technical assistance is able to precisely identify the cause of the malfunction.

What happens if the boiler pressure is too low?

Too low a pressure leads to boiler lockout: the radiators do not work and the water does not heat up. A code on the display which indicates the type of failure or problem which can be identified by consulting the specific manual.

To ensure that the lockout is due to a pressure lower than 1.2 bar, the value indicated by the manometer must be read. At that point, it is necessary to proceed by opening the filling tap, making sure to close it when the operation is complete to prevent the pressure from continuing to rise.

One event that should not be excluded is that the boiler pressure drops to zero. It's not that common, but it shouldn't be ruled out a priori. The cause is most likely to be found in the formation of limestone in the pipes or in the breakage of a component. To avoid such a scenario, it is necessary to schedule regular maintenance by a specialised technician who also contributes to savings on intervention and repairing costs.

What should the boiler pressure be with the radiators on?

With the radiators on, the pressure can even reach 2 bar. There is no need to be excessively alarmed: by venting the radiator inside which an air bubble has formed, the pressure is brought back to the optimal range between 1.2 and 1.5 bar.

However, if the level tends to exceed the maximum limit, going up to 2.5/3 bar, you must immediately contact a qualified professional for a complete check of the boiler.