Steven Knight’s body was found at his home on Victoria Road, Platt Bridge, when he did not go to work on Sunday, November 21.
But Bolton Crown Court heard it was not possible to say why the 49-year-old had not been able to escape the blaze.
He may have been intoxicated after drinking alcohol, blacked out due to an undiagnosed medical condition, asleep or overcome by smoke.
Mr Knight went to the pub on Saturday, November 20 with friends and his children, Georgia and Devon Knight. He left between 10pm and 10.30pm and walked to his home nearby.
Devon left soon afterwards and popped in to see his dad for a short time, who was cooking on the stove.
But the next day Mr Knight, a self-employed joiner, did not go to work at 10am as arranged and Viqar Akram, who he was working for, went to check on him just before 2pm.
He told the court Mr Knight had not answered phone calls or text messages, and there was no response when he knocked on the door.
Mr Akram noticed the windows of the house were black and managed to get inside.
He said: “Everything was black. The gas was on and the pan was on the floor.”
He found Mr Knight and attempted to resuscitate him, but emergency services attended and confirmed he had died.
A post-mortem examination found he died from smoke inhalation, with his carbon monoxide level at 60 per cent – compared to one to two per cent in non-smokers and five to six per cent in smokers.
Consultant pathologist Dr Naveen Sharma said: “This was 10 times the levels which are ordinarily found in smokers and this was within the range found in carbon monoxide fatalities.”
Tests showed he had 210mg of alcohol in 100ml of blood – nearly three times the legal limit for driving of 80mg.
Dr Sharma said alcohol did not cause his death, but it can cause drowsiness and could be one reason why he did not escape the fire.
The inquest also heard Mr Knight sometimes had a “funny turn”, where he would black out, but doctors had not been able to establish why.
He could sometimes predict when it would happen and had told friends he thought he was due to have a black out in the days leading up to his death.
Fire investigator Peter Stone, from Greater Manchester Fire and Rescue Service, told the court the blaze had started in the kitchen.
The gas hob was “significantly damaged” and the extractor fan had fallen onto it, while there was a chip pan on the floor.
There were no working smoke alarms in the house to warn Mr Knight of the fire, but he said people could be incapacitated “relatively quickly in a large amount of smoke”.
He concluded oil in the chip pan had caught fire, before being knocked to the floor when the extractor fan collapsed onto the hob.
Coroner Peter Sigee said while it was possible that alcohol played a part in Mr Knight not responding to the fire, there were several other possible explanations. He recorded he died as a result of an accident.