Two neighbours died in hospital, days after an explosion which happened as one of the neighbours tried to replace a faulty valve on a gas heater.
Emergency services were called to Church End, near Coleshill, Warwickshire, on 17 December.
An inquest heard retired gas fitter Frank Adey, 80, had been helping Audrey Ward, 77, replace the valve in a portable heater.
The heater then exploded when the ignite button was pressed.
Mr Adey died on 18 December and Mrs Ward on the 27th. Both had suffered severe burns and died in hospital.
The inquest heard that Mr Adey had always replaced Mrs Ward's gas canister but on this occasion he had noticed the valve was faulty.
He has sought advice from a shop and bought a replacement valve and fitted it, but the explosion occurred when it was lit.
Coventry's deputy coroner Louise Hunt recorded verdicts of accidental death.