Throughout Europe, boilers are the most popular appliance for providing central heating and hot water in the home.

Depending on what fuel is available in the home, boilers can run on natural gas, liquid gas, oil or electricity.

Boilers can be wall hung or floor standing. Wall hung boilers are more popular because they take up less space than floor standing boilers. However, traditionally, floor standing boilers have a higher output and are especially suitable for larger properties.

Types of boiler:

Open vent boilers - Sometimes known as heat only boilers, provide central heating and hot water using a boiler, a hot water storage cylinder housed in an airing cupboard and water tanks in the loft.

Combination boilers - Combination boilers or combis, provide central heating and instant hot water so they do not need a separate water storage cylinder.

System boilers - System boilers are often referred to as sealed system boilers. They provide central heating and hot water via a storage cylinder housed in an airing cupboard. However, there is no need for water tanks in the loft, as with an open vent boiler.

Some boilers have an integral hot water storage tank. These combination-store, or combi store, boilers are usually floor standing.

Boilers can be either conventional or condensing.

The term condensing, or high efficiency, means the boiler recovers more heat from the amount of oil or gas that is burnt, making it more efficient than conventional boilers. By recovering and using heat that would otherwise be lost up the flue, the best condensing boilers are more than 90% efficient. Although condensing boilers cost more initially, they are very economical to use, and can pay back the initial extra cost in fuel savings. Condensing boilers also have lower emissions of toxic gasses making them much better for the environment. - Description added by: Baxi

The most important groups of fuels are fossil fuels, bio-fuels, hydrogen and nuclear fuel (uranium). Of these fuels, only bio-fuels and hydrogen are strictly renewable, but in both cases, this really depends on the energy source used to produce it. We have traditionally been heavily dependent on fossil fuels (first coal, then oil and now natural gas) and more recently on nuclear power. In the future, we will need a more sustainable range of fuels for all potential uses. New technologies such as fuel cells may require a wider range of fuels (e.g. hydrogen) and widen the range of applications for which fuels may be used (e.g. methanol-fuelled fuel cells to power laptops). There are many controversial topics surrounding fuels, from carbon emissions and climate change through the potential for bio-fuel crops to compete with food crops to the whole debate around nuclear power generation. - Description added by: David Lockie