A family of seven from Sydney's east have been taken to hospital after a carbon monoxide leak that has been traced to a pool heater, prompting emergency services to warn of the importance of properly maintaining gas-powered appliances.

Fire and Rescue teams attended the house in Wentworth Road, Vaucluse, on Monday afternoon after the family reported experiencing symptoms of asphyxiation, including nausea and dizziness.

Emergency services soon detected the presence of carbon monoxide in the house. The source of the toxic gas appeared to be a gas pool heater, Superintendent Joshua Turner from Fire and Rescue NSW said.

The family - five children and two adults - were taken to the Sydney Children's Hospital and Prince of Wales Hospital in stable conditions.