EPA stoves fall under a general category of appliances that use either a baffle to create a reburn effect of the combustion byproducts in the combustion chamber or a catalyst to help create a complete burn at a lower temperature, while filtering out harmful emissions. In order for the EPA stoves to work properly, they use smaller, well insulated combustion chambers. Where non-EPA models typically just consist of a generic combustion chamber, EPA models are engineered to work in conjunction with their air injection systems, creating a hot and clean burn, while allowing longer burn times. Almost all municipalities now require EPA appliances for new installations and non-EPA models that have not been grandfathered in can no longer be installed. However, EPA appliances are vastly superior to their predecessors and once their operation is mastered by a consumer, they are fantastic to use.