Caroline Merkel, 48, and her son Dylan, 21, had been feeling light-headed and generally unwell for the past several weeks.

After thinking it might be her iron levels, Ms Merkel picked up some vitamins.

It wasn’t until she saw an awareness add on television about carbon monoxide poisoning that things clicked.

After some phone calls to public housing, a plumber recorded three times the normal level of carbon monoxide in her home on Monday.

The heater was removed and the family are waiting for a new one to be installed.

Ms Merkel has been living in the same public housing home for almost 25 years and in that time the gas heater had never been serviced.

“Public housing check smoke alarms annually, but there’s nothing in the system stating they need to check gas heaters,” she said.

“We were potentially living in this house with a killer.

“The gas heater was like a ticking time bomb and it was only a matter of time before it went off.”

Ms Merkel and her son have seen their doctor and have been advised to have blood tests.

“I just want people to be aware that this can and does happen,” she said.

“It can be fatal for not only the young but also the elderly who sit in their homes for extended periods.

“We never had the heater going all night and our bedrooms are towards the back of the house.”

A Department of Family and Community Services spokesman said a contractor visited the property on Wednesday and disconnected the unit.

He said a new heater would be installed today.

The department refused to discuss its policy regarding the servicing of gas heaters.

In 2010, two boys Tyler and Chase Robinson, aged six and eight, died in their Mooroopna home from carbon monoxide poisoning.

The Chase and Tyler Foundation was established to helpprevent similar deaths.