Test and examination criteria for vented gas fireplace heaters for use with natural and propane gas, which allows the view of flames and provides the simulation of a solid fuel fireplace and furnishes warm air to the space in which it is installed with or without duct connections. A vented gas-fired fireplace heater is designed to comply with minimum thermal efficiency requirements and may be controlled by an automatic thermostat. Direct vent appliances may be installed in manufactured (mobile) homes and recreational vehicles.