Retired engineer Malcolm Stocks suffered neck and facial burns in the incident – and though they were not severe they precipitated his death.
The 66-year-old of Redbrook Maelor, near Whitchurch, died at the Wrexham Maelor Hospital a few hours after the accident on April 9.
An inquest into his death, held at Ruthin, heard that in 2015 Mr Stocks, who was divorced, was diagnosed with Chronic Obstructive Pulmonary Disease (COPD) and asbestosis in 2015.
Consultant pathologist Dr Mark Atkinson, who carried out a post-mortem examination, gave the cause of death as COPD, with the burns as a contributory factor, but reported that Mr Stocks did not, in fact, have asbestosis.
His daughter Eve Doyle said her father had been heavily medicated and his condition had deteriorated over the past two years. In January this year he began palliative care.
In a statement read at the hearing his sister Melinda Pharaoh, who was staying with him, said she was awakened shortly after 1am by her brother screaming.
His hair and clothing were alight and she doused the flames with a wet towel before calling the emergency services.
She said her brother, who had nasal tubes supplying him with oxygen, sometimes had difficulty coughing and so lit a cigarette to clear his throat.
Recording a conclusion of accidental death, John Gittins, coroner for North Wales East and Central, said that although the COPD was a natural cause the burns more than minimally contributed to his death.