Gas fired infra-red heaters are highly efficient producers of infra-red energy that can be used in numerous heating applications. Their greatest uses to date have been in the heating of industrial and commercial buildings, spot and area heating, commercial food broiling and cooking and in process heating ovens. Solaronics gas infra-red heaters, high and low intensity, convert a high rate of their input to infra-red output. Input energy not converted into infra-red is released as convected heat and water vapor. Unvented units, high or low intensity, return a total of 92% of input to the space they occupy. Vented units, only low intensity may be vented, return up to 90% of input to the space they occupy. The longer the unit, the higher the percentage.