Gas Gas fireplaces are designed to burn either natural gas or propane. They emit very little pollution, need little maintenance, and can be installed almost anywhere, especially in a new home. Gas fireplaces have BTU ratings that measure how much heat is produced by the hour. They are also rated by fuel efficiency; that is, the amount of fuel consumed to generate heat and attain the ideal BTU. Direct-vent and top-vent gas fireplaces have an efficiency rating of 40 to 80 percent, meaning that, at …
