It's a common household appliance used by many of us in our homes...
Gas heaters are a popular choice for keeping warm during these cold winter months and while they're considered to be more environmentally friendly than the electric alternative they must be used with caution.
Three years ago Vanessa Robinsons two young boys died from carbon monoxide poisoning caused by a leaking gas wall heater in her rental property.
There was no warning and no signs... The leakage from the un-serviced appliance killed her boys silently during the night.
Vanessa somehow survived although the toxicity led to complete renal failure… Heart and liver damage and short term memory loss.
The next thing I remember was being in excruciating pain and I remember bits and pieces... It was a very strange feeling and my head wasn’t thinking properly… Your children leave such an empty space and where you used to go home to your kids there's nothing there anymore… so it’s really, really hard,” says Vanessa.
The landlord was recently cleared over the deaths of her two boys by the Victorian Coroner despite not having the gas heater checked for over six years.
It's devastating incidents like this that gas expert Frans Sterk hopes to prevent.
"It’s very poisonous, they do call it the silent killer, it's odourless, it's tasteless and it's there and you wouldn't know it," says Frans.
Carbon monoxide discharged by faulty gas appliances is a silent killer...
"Every two years you should have your gas appliance checked and serviced," says Frans.
He runs Gaswatch... which specialise in maintaining gas heaters and checking for any signs of carbon monoxide.
"In the past two weeks I had two customers where they were producing carbon monoxide in their living room," explains Frans.
While you won't know it's there, these are some indicators you can watch out for...
"You can have a look on the flu to see if there are any black marks there. You can have a look on the side of the heater for discolouration, that's usually a sign that carbon monoxide is present, if you can see the flame it should be a blue flame not a wavering orange flame inside the heater," says Frans.
According to Frans it doesn't take much for a gas heater to become faulty... A build-up of dust or lint can often be the perpetrator.
"It certainly speed ups the process of blocking up the airways into the heater which causes carbon monoxide to be produced," says Frans.
Phil Evans from the Metropolitan Fire Service says they attended nearly 50 fires in 2012 that were attributed to gas heaters...
"If you don't maintain those pieces of equipment properly you are putting yourself and family at risk you may have them malfunctioning which could lead to house fires and put people in serious danger," says Phil.
He says it's vital to have your gas heater installed by a professional and checked biannually to prevent a fire and eliminate the risk of carbon monoxide poisoning.
"If you don't get them checked what you will find it starts off with mild headaches, nauseous, tired all the time… the effects go on to unconsciousness, vomiting, I think you'll especially find in young kids, babies or the very elderly," says Frans.
But prevention is the key...
"Very often when it is happening it can be too late," warns Hans.