Direct-vent style gas heaters are safer for children than other models of gas heaters, but there are still significant safety issues for children with these appliances. Children can still seriously injure themselves on hot surfaces on some models.
Most direct-vent heaters do not have an exposed flame, so it is harder for children to burn themselves as compared to some older or outdoor-use heaters that have open flames. However, surfaces on these heaters can still reach high enough temperatures to cause burns. This is particularly a concern on fireplace-style, direct-vent heaters that have viewing ports, since the glass and mesh screens in the viewing port can become hot quickly.