A heating engineer who duped customers into believing he had official gas safety qualifications has been jailed for 21 months.

David Hoskin carried out work replacing boilers in the homes of 10 people – some elderly – while not having the necessary Gas Safe registration.

Maidstone Crown Court heard that although he had worked in the industry for several years, he had allowed his safety qualifications to lapse.

Hoskin also duped people into believing he had worked for British Gas, could get them £400 cashback as part of a government-backed boiler scrappage scheme and told one customer he would remove an asbestos tank in his loft for £150 as it was an imprisonable offence to have one.

The court heard he also "abused and threatened" a 72-year-old woman, telling her he would take a charge out on her house if she did not pay £750 of an outstanding bill.

Hoskin admitted four fraud offences, seven of engaging in a commercial practice which was a misleading action, four offences of engaging in an unfair commercial practice, and one of engaging in a commercial practice which was aggressive, between December 2009 and March 2010.

Passing sentence, Judge Philip Statman said Hoskin, who has previous convictions for deception and one for a similar offence of making a false statement, offered a service based on him having the competence and skills required.

"You told your customers that you were fully qualified to conduct this work and you were not," he said. "They trusted you. They thought you had the requisite skills and qualifications but you were not Gas Safe registered under the regulations at the time."

Alison Ginn, prosecuting, told the court some customers were left footing additional bills to rectify faults with Hoskin's work. She said the actual total financial loss ranged between £1,500 and £5,000.

One woman's boiler failed days after being installed and an 85-year-old man was later advised the heating system fitted by Hoskin should be replaced.

However, Judge Statman said he accepted Hoskin had not deliberately targeted elderly and vulnerable victims.