The Potterton Profile is a very reliable boiler, but it does have some problems, mainly with the circuit boards and fans.
You may be experiencing the fan cycling on and off and then settling after a while.
This can be either the fan is running slow, not being able to operate the air pressure switch, the air pressure switch may be faulty or sticking, or most commonly a fault with the PCB.
How to identify the part I need?
407677 - this is the main circuit board that fits all Profile boilers and also Prima boilers.
409583 - fan, this fits Profile 30 - 60
409569 - fan, this fits Profile 80
409573- fan, this fits Profile 100