Your chimney could be on fire and you wouldn't know it.
The New Zealand Fire Service is running an online campaign reminding homeowners to get their chimney cleaned this winter, to prevent the chance of a chimney fire.
In Masterton, the fire service attend a chimney fire every couple of weeks - about the norm, said Masterton fire station officer Doug Flowerday.
He said a chimney fire is very visible from outside the house, with flames and sparks coming from the chimney, possibly coupled with black smoke.
But it might not be apparent to those inside.
The New Zealand Fire Service is called to around 600 chimney fires in New Zealand every year.
The danger is, by the time a homeowner realises the chimney is on fire, it might have spread to other parts of the house.
Carterton fire chief Wayne Robinson said if people see a chimney fire, they should call 111 immediately.
"Then notify the residents of the house involved."
Mr Flowerday said dry wood is best for fires. "The damper the wood, the sootier chimneys become," he said.
Creosote residue builds up and blocks chimneys quickly.
The more resin in the wood, the more build-up of moisture content which will damage the inside of chimneys.
He said cleaning your chimney at the beginning of winter and then again during the season is recommended to ensure chimney safety.
Installation of fire alarms as a safety precaution is also strongly recommended.
Mr Robinson said they had been spared chimney fire callouts this winter.
"Touch wood, Carterton hasn't had any."