The Health and Safety Executive (HSE) has urged homeowners to ensure they only employ qualified and registered technicians to work on their gas appliances.
The call follows the conclusion of a case at Kings Lynn Magistrates' Court where a self-employed heating installer was fined £2,000 and ordered to pay costs of £1,000 after carrying out substandard gas work.
Ryan Neale, of Blenheim Road, King's Lynn, Norfolk, completed the work despite not being Gas Safe registered – a legal requirement.
HSE inspector Paul Unwin said: "This case highlights the need for householders to exercise caution when they select people to work in their home.
"They should always check the person they commission is registered with Gas Safe and competent to carry out the work, and obtain references for similar works done."
Russell Kramer, chief executive of Gas Safe Register, added that people should always ask to see their engineer's ID card. Gas safety credentials can also be checked by calling 0800 408 5500 or going to www.gassaferegister.co.uk.