So how does a boiler actually work?

A modern boiler is a sophisticated machine, needing several internal components to function safely, such as a Pressure Release Valve (PRV) which regulates water pressure, an expansion vessel to accommodate increased pressure due to the water heating process and a fan to discharge waste gases caused by the heating process through a flue.

In addition, a number of devices external to your boiler can also be very useful, such as a main thermostat that monitors room temperature to switch your boiler on and off as the room falls and rises in temperature. You can also use a time switch to turn your boiler on and off (depending on room temperature) at certain times of the day, such as when you wake up or get home from work.

If you fit Thermostatic Radiator Valves (TRVs) to your radiators, you can even control the temperature of an individual radiator in a particular room so that it is hotter or colder than the rest of the house.