The man cannot be named after a judge granted final name suppression after a request from the youngster's family who want his identity protected.
The unemployed man earlier pleaded guilty to a charge of causing grievous bodily harm with intent to disfigure the boy during the attack on July 20 this year.
It happened at the family home in the Shirley area of Christchurch when police say the boy accidentally knocked over a fan heater, which made a burn mark on the carpet.
The man then lost his temper and "took hold of the heater and forcibly pushed the hot metal protective grill at the front of the heater on to the boy's face, causing deep burns to his facial skin," according to the police summary of facts.
The boy was left with severe third-degree burns to the right side of his face - from his eyebrows to his chin - as well as his ear.
Police said at the time that the boy required major surgery, including skin grafts, to limit the scale of disfigurement.
When police arrested the man the day after the attack, they also recovered the fan heater, which was found with burnt skin tissue still sticking to it.
Detective Sergeant Darren Folau, of the police child protection unit, earlier described it as a "horrific" case.
But he was amazed by the boy's "remarkable resilience".
Child, Youth and Family have been working closely with police to support the child and family.
Today at court, the man waved, mouthed words and interacted with two supporters in the public gallery.
Judge Alistair Garland said the sentence on the burning charge had to send a "clear message that offending of this kind will not be tolerated".
The man was sentenced to six years, 11 months in prison in total, including for his 24th driving while disqualified conviction and two charges of receiving stolen property.
Judge Garland sentenced him to five years, five months jail on the burning charge, plus an extra 14 months on the driving charge, and another four months on the two receiving charges.
In granting him final name suppression, Judge Garland said the interests of protecting the child's identity outweighed the public interest in knowing who he was.
Child, Youth and Family said today it had been working with other agencies to monitor the boy's recovery "ever since he was seriously injured in such a horrendous manner''
"No child should ever have to experience what this little boy went through,'' said CYF's southern regional director Kelly Anderson.
"We, with other agencies, continue to support the boy, his mother and the wider family through what has been a deeply distressing time for all involved.''
