Leamington Magistrates have fined an installer £4,000 for an 'immediately dangerous' gas fire installation.
Crane, who trades as Peter Crane Plumbing & Electrical, installed a gas fire in house in September 2009.
The occupants of the house fell ill with flu-like symptoms including tiredness, headaches and vomiting after using the fire for around four hours a day.
The Health & Safety Executive (HSE) found the heating appliance produced high levels of carbon monoxide, although a catalytic converter within the appliance reduced these to safe levels.
HSE inspector, Peter Snelgrove, said Crane had failed in his duty of care by installing a fire that was "immediately dangerous".
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