Good morning, my boiler doesn’t have that button. It turns on and off. If you do not have the room temperature thermostat, it is regulated with the internal thermostat when having the bridge. Once the water reaches the temperature that the boiler is programmed for and when the temperature drops it starts again. But when you remove the bridge, that doesn’t work, it doesn’t start until you close the relay. I take this opportunity to comment that in the graphics, I don’t know if more hours could be added, I explain myself. When you pass the pointer through the graph, it tells you the desired temperature, actual temperature, whether the heating is working or not. In that balloon, could you add the hour with minutes? A greeting!