Heat Man is one of the Robot Masters created by Dr. Wily in the end of issue #8. He is featured in issue #10, where he is the third Robot Master to fight Mega Man. Ironically, he complains about the high temperature of the building and wonders if the robot he is based on, Fire Man, also isn't resistant to heat. While Mega Man offers a chance to surrender, he politely declines and immediately attacks him, although not before thanking him for the offer. Mega Man defeats him with one shot of Bubble Lead. Still functioning and cooled off, Heat Man tells Mega Man that the rest of the Robot Masters are ready for him. Mega Man responds by shooting him in the head at point-blank range with the Mega Buster, destroying him. This uncharacteristic act of brutality from Mega Man clued Dr. Light in on Wily's plan of infecting Mega Man with a virus.
Heat Man and the Robot Masters were reconstructed by Ra Moon and he, Dr. Wily and Quick Man explore Lanfront Ruins. While not angry at Wily at being destroyed, Heat Man asks why Wily didn't tell him about the heat regulator installed on his back. They find an ancient robot that is repaired and named Shadow Man. All of Wily's Masters subsequently serve as part of an army assembled by him and Dr. Eggman in the Skull Egg Zone to battle Mega Man and Sonic the Hedgehog's allies. Together with other fire-equipped Robot Masters like Burner Man, Pharaoh Man, and Magma Man, he was deployed against Blaze the Cat, but their fire was then turned against them by the pyrokinetic. These events were later written out of the timeline due to Mega Man reversing the doctors' Genesis Wave.
Because of Ra Moon reconstructing them, Heat Man and the rest of Wily's robots ended up serving Ra Moon after the alien supercomputer betrayed the doctor. Heat Man, alongside Bubble Man, Flash man, and Metal Man, later confronted Mega Man as well as Guts Man, Bomb Man, Cut Man, and Rush shortly after the latter group's arrival at the Amazon. Heat Man utilized his Atomic Fire ability to force Mega Man into a lake, the latter also questioning how they are even present due to their destruction earlier. Heat Man proceeded to taunt Mega Man with "coming back from the dead." Heat Man later attempted to attack Mega Man again, although he was stopped by Mega Man's Bubble Lead ability again, having copied it from Bubble Man immediately beforehand.
He later appears, alongside the rest of Wily's first series of robots, Guts Man, Cut Man, and Break Man, to aid Mega Man and Guts Man in fighting Ra Moon, although he is eventually shot down by Ra Moon during the battle. He was subsequently revived and repaired after Ra Moon's defeat, and joined his Mega Man 2 brothers in beginning work on a new Wily Castle while the rest of Wily's Robot Masters hunted down the renegade Shadow Man. Following the completion of these tasks, the Mega Man 3 series stole Gamma's Energy Elements and scattered to draw out Mega Man.
Heat Man and his brothers had their Integrated circuits and weapon data taken and implanted in the Doc Robot. His body and those of his brothers were stored at the Wily Castle while their minds worked together to control their new form. This arrangement didn't last long, as the feuding personalities overloaded the body after their fight with Mega Man.
Heat Man and his brothers were later revived by Dr. Light and his team, and Air Man wound up cooling Heat Man off as they were all being repaired. Dr. Light then offered all sixteen of Wily's former Robot Masters the opportunity to serve new purposes. Heat Man was one of eight, led by Quick Man, who chose to be deactivated instead, and was placed on display in the Robot Master Museum.