[davidmanze]

Note most if not all aquarium heaters are not designed to be operated out of water. You might want to double check that it is working as you intend.

 

 I have placed the aquarium heater inside a steel tube which is welded to a steel right angled plate which is bolted to the body of two the safes....... The thermostat is in the upper part of the heater and it's rubber support fits snuggly in the tube. set to 26°. It cuts in and out giving a low level of warmth.  

  It works a treat!