It had been a damp week in Auckland so Sandy Martin pulled out her dehumidifier and switched it on before she left for work.
During the day the unit, which was more than 10 years old but still going strong, overheated. It set the room alight as it melted.
Martin's clothes, furniture and irreplaceable keepsakes were destroyed - including home videos and baby clothes. Anything that survived was left coated in thick grease.
"The room was totally black," the mother-of-two said. "There were smoke webs hanging from the ceiling, where nylon and plastic had melted."
Firefighters said the house, in a quiet Pakuranga cul-de-sac, was saved only because her bedroom door and windows were closed. The fire extinguished itself after sucking the oxygen in the room dry.
Martin said: "I could have lost my whole house."
With no smoke alarms in that area of the house, the alarm wasn't raised until her 20-year-old son, Aaron, arrived home from work.
The family dog, Pippa, was inside and Martin feared she would have been caught in the blaze if it had spread.
"Aaron found the house full of smoke. Pippa was running around like a mad thing. I got a phone message from him that said 'Mum you better get home, the house is on fire'.
"He turned the electricity mains off and called the fire service. To come home to the fire brigade being here ... Everything was a mess. My heart was in my throat."
Martin was grateful no one was hurt and said it was a wake-up call that smoke alarms needed to be installed in every bedroom.
"You just never think it's going to happen to you."