I have an Ariston Class X boiler installed a year ago with a Rowa girl pump in the hot water inlet. But as cold water there was no pressure install a new pressurizer at the exit of the tank. Now the water pressure is perfect for hot cold but the water does not maintain a constant temperature. Continuously heats up to a maximum then it warms up and then heats up again. Which may be? A lot of pressure or flow? Any parameters to configure? Thank you

Indeed the problem was the exchanger that was dirty. When the tank was emptied, the bottom sediments came out and that made the boiler dirty. Thank you!