A schoolboy was killed by poisonous fumes which leaked into his bedroom as he slept.

An old central heating boiler directly below 12-year-old Joshua Ingamells' room belched odourless and tasteless carbon monoxide gases.

His body was found by his father, Graham, after he called out to his son at 6.45am to get him up for school.

As a coroner ruled the cause was accidental death, Joshua's family today made a tearful plea to homeowners to have their central heating checked, adding: "Words cannot express our loss. We didn't know we were in danger."

Joshua, a student at 1,000-pupil St Richard's Catholic College, in Bexhill, was pronounced dead at the Conquest Hospital, St Leonards, in February Mr Ingamells, a builder, said: "As soon as I opened his door I knew something was badly wrong. There was a warm, humid smell - something I've never smelt before."

The Hastings inquest heard yesterday Joshua had 61 per cent carbon monoxide saturation in his body. Fifty per cent is fatal.

The boiler which fed the Ingamells' five-bedroom detached house in Fairlight Road, Hastings, had been seen by an engineer only once in 16 years.

However, an inspection after the tragedy found it was in "exceptionally poor" condition.

The tragedy happened on February 10, the morning after Joshua, his sister and father visited an uncle in Bexhill to celebrate a birthday.

Joshua asked to return home at 10pm to complete some homework. All three came home while their mum, Margaret, and two other siblings were out of the house. Mr Ingamells told Joshua it was getting late and his last words to him were: "Don't worry Dad. I'm on top of my homework. Wake me at the normal time."

At 6.45am the following morning Mr Ingamells was woken by his son's alarm clock from his bedroom.

He said: "I sat up and called out to Joshua. I called again without any response so I jumped out of bed, went into his room and the heat just hit me."

Joshua was there lying on his back. Mr Ingamells shook him before running downstairs into the office where the boiler was located and turned it off.

After dialling 999, he was advised to switch the main gas supply off.

Mr Ingamells and his daughter had managed to escape any serious intake of fumes because their bedrooms were further away. However, the daughter, who was not named, collapsed on a landing and was taken outside for air.

Mr Ingamells said because the boiler had not broken down, there had been no reason to call in engineers.

Roger Koster, a former British Gas engineer for 30 years who now runs a gas consultancy in Brentwood, Essex, said boilers should be serviced annually. He added: "The appliance itself was elderly. It was in exceptionally poor condition."

He added there was no legal responsibility on anyone to service boilers. East Sussex Coroner Alan Craze said many people operate on the philosophy that if it is not broken, don't fix it.

He added: "People know as a matter of theory their central heating appliances need to be serviced regularly."

Outside Hastings Magistrates Court, Joshua's uncle, Paul Ingamells, read a statement.

He said: "Joshua was a very special boy. He was dearly loved by all his family and all who knew him.

"We've all been devastated by this tragedy. Words cannot express the sense of loss. We were unaware of any dangers to our family at any time.

"We do hope other families realise the dangers of everyday household appliances we can all take for granted.

"We would urge other families to be diligent in getting their boilers checked regularly even if they seem to be working all right. Perhaps invest in a carbon monoxide alarm to prevent a tragedy like this happening again."