Most domestic heating oil boilers in the UK are of a “pressure jet” design.
The heating oil stored in the main tank is pumped through a nozzle under pressure to create a fine spray of fuel and air is also blown into the combustion chamber by a fan. The finely atomised fuel mixes readily with oxygen in the air to produce a flammable mix, that when ignited by an electrode generates a highly efficient burning flame.
Hot exhaust gases pass through a heat exchanger, usually a copper coil, transferring energy to the water circulating through it. This hot water is then distributed throughout the house via radiators which subsequently warm the rooms as appropriate.
Although radiators remain hot, the boiler does not operate all the time. It switches on and off depending on the boiler water outlet temperature setting on the boiler and the room temperature where the thermostat is located. If the heating system is switched on water constantly circulates throughout the boiler, heat exchanger and radiators extracting heat from the burning fuel.
An oil boiler will fire more regularly and use more fuel in colder weather to compensate for the additional heat lost through home walls, floor, windows, and roof etc.
The energy used is proportional to the temperature differential between the house room temperature and the outside ambient temperature. For tips for on how you can save energy in your home, click here to see our Energy Saving Tips page.