Boiler does not switch to the second stage. Troubleshooting

Greetings! Here is another article about boiler malfunctions and this time we will analyze an interesting case when the Miura boiler does not switch to the second stage in automatic mode, while there are no visible problems or alarms.

In fact, the problem was that the boiler could not increase pressure and stop, it was working all the time. After that, it was noticed that it did not use the second stage (High Combustion) to supply more fuel to the injector.