As of Friday 20 June 2014, Weiss Heat Transfer Units will be prohibited from sale and use. There have been three recent instances of these units catching fire.
The units operate in ceiling spaces and move air through ducts to heat houses. Units manufactured up to May 2012 are affected: Weiss Heat Transfer Units FV 602, FV 603, FV 652 and FV 653. They were sold through Mitre 10 and possibly other retailers.
What to do
If you have a unit immediately turn it off. Get advice from either the manufacturer (0800 208 008) or a registered electrician.