Most of the heat from an open flued gas fire or solid fuel fire goes straight up the chimney. By comparison 100% of the heat generated by a flueless gas fire goes to heating the room. Tests commissioned by Burley compared a 2.5kW flueless gas fire (Burley Environ), a typical 6kW inset flued gas fire (quoted efficiency 59%), a decorative flued gas fire and a 2kW electric fire. These tests showed that the flueless gas fire produced over 3 times more heat per kilowatt than the flued gas fire and over 12 times more heat than the decorative gas fire. In other words the flued gas fire lost over 70% of the heat up the chimney and the decorative fire lost over 90%. If the 15 million flued gas fires in Britain were replaced by flueless fires, the country would save around 23,500,000,000 kilowatts of gas every year (costing £1,600,000,000) which in turn would reduce carbon dioxide emissions by over 4,200,000 tonnes every year.

Chimneys and flues are fraught with potential problems, all of which will stop a flued fire from operating safely.

1. The fabric of the chimney could collapse.
2. A nest or debris could block the flue.
3. Atmospheric conditions or open doors can create a down draught.
4. Extractor fans can create a draught to reverse the pull of a chimney, causing it to spill the products of combustion into the room (this makes flueless gas fires particularly popular and safe for use in pubs and restaurants).

Burley's flueless gas fires suffer from none of these problems.