The printed circuit board or Pcb as it is commonly known is the boilers central control. It constantly checks every process that occurs via the sensors, switches and thermostats. It also enforces the safety protocols, making sure that the boiler ceases to function if any of the internal readings point to any kind of error or fault. The printed circuit board is essentially the brains of the appliance, ensuring everything is running correctly and safely. this is located behind the user control section of the boiler. It runs and monitors the entire boiler ensuring it monitors all the temperatures, airflow pressures, water pressures, water flow within the boiler and controls the gas supply to the burners. This is achieved by receiving information from these safety devices within the boiler such as thermisters, temperature sensors, air pressure switches, transducers, pressure switches, gas valves and many more. If any of the safety devices detect excessive readings or fail to work the information is sent back to the printed circuit board which in turn switches off the boiler to ensure safety to life and property. The printed circuit board regulates all the gas pressures sent to the burner it also runs the fan and monitors its condition, it runs the pump and monitors the flow of water that the pump is creating and also ensures the boiler runs safely and efficiently all the time. There are a number of different types of printed circuit boards and these are categorised as Main or Primary, Ignition, Display and Interface.