Just got a reply from Hagen/Fluval
Dear Mr XXX
Thank you for your e-mail.
The E heater may have need to be reset, to do this turn off the heater and re-position the heater on a 45 degree angle, then turn on the heater and turn down the temp as low as it will go,18" ,then turn up the heater as high as it will go ,34" ,after this set the heater at the desired temp and leave at a 45 degree angle making sure it is totaly submerged
We have had no problems with the heaters,the only issue we have had, is that the heaters need to be positioned on a 45 degree angle to disperse the heat .The heater are so sensitive, they will sometimes read the water temp inside the heater guard if positioned verticaly.
If non or the above helps please call me or return it,along with your proof of purchase to your supplier for replacement under warranty,as it has a 5 year warranty with them.
Hope this helps
Aquatic Customer Service/Technical Advisor
Rolf C. Hagen (UK) Ltd.
Whitwood Industrial Estate
Castleford, West Yorkshire
phone: +44 (1977) 55 66 22
fax: +44 (1977) 51 34 65
Don`t know if this will help. Perhaps someone could try this idea.