Firefighters were shocked to find a makeshift heater, made from a portable camping stove with an up-turned terracotta pot bolted on top, when they attended a NSW home on Sunday afternoon.

They were initially called to assist paramedics bring an elderly woman down from her two storey building as she had gone into cardiac arrest.

But what they also discovered at the woman's Hawks Nest home - on the mid-north coast of NSW - was the extremely hot home-made heating device which could have potentially 'blown up' the house, the Daily Telegraph reports.

Firefighters were shocked to find a makeshift heater made from a portable camping stove with an up-turned terracotta pot placed on top when they attended a NSW home on Sunday afternoon

The extremely hot home-made heating device which could have potentially 'blown up' the house, a Fire and Rescue NSW spokesman said

The woman was taken to hospital after firefighters helped remove her from the building by using a slide ladder from the veranda, according to the Fire and Rescue NSW Facebook page.

While they believe the makeshift heater may not have caused the woman's cardiac arrest, firefighters say the device 'put her at great risk of starting a fire in her home and carbon monoxide poisoning'.

'When they get hot, the gas cylinder that's inside the machine, which is about the size of your average can of fly spray, has enough LPG inside that container to blow up your house,' a Fire and Rescue NSW spokesman also told the Telegraph.

Earlier this year, NSW Fair Trading banned a number of low-cost gas cookers and issued a safety warning against them.

The portable cookers, commonly used for camping, can potentially 'overheat and explode'.

Firefighters are urging householders to use heaters that are approved and meet Australian Standards.