Your boiler is making unusual noises because of internal blockages or issues with how it regulates heat or water flow, which can put unnecessary strain on the system.

Technical description

Over-gassed; Sludge/scale in the heat exchanger; Faulty boiler thermostat; Water section push rod sticking; Gas valve sticking open; Dirt/swarf on gas valve facing; Resistance to water flow; Water filter blocked; Venturi blocked; Wrongly positioned feed and vent; Incorrect inhibitor in system; Pump noisy or vibrating.