Conventional chimneys are easily recognisable. The stack rises well above the roofline and is topped by a traditional chimney pot or, possibly, a gas terminal.

You will see a metal flue cowl on your roof. Some are all metal whilst others may terminate through a short terracotta pot (but without a chimney stack).

Many modern homes have been built with such flues. You can readily identify them by either a raised ridge terminal or by a metal flue cowl on your roof.

Some properties have no chimney or flue, in which case a balanced flue or powered flue is needed. Even without a chimney or flue, most fires can be fitted into your home, so there's no need to be left out in the cold.

Flueless gas fires are very efficient and are becoming more and more popular.

Balanced flues do not require an electricity supply. They operate via a twin-walled pipe which exits horizontally through an external wall or vertically through the roof. The outer pipe draws air from the outside while the inner pipe expels the products of combustion.

A powered flue uses an extractor unit mounted on an outer wall to vent the combustion gases directly outside. A mains electricity supply is needed to operate the system.