In the olden dayes, we used separate thermostats (in glass tubes) and heaters. When combo units became the rage, I discovered you could disect one and convert it to thermo only operation. If I wanted a "heat controller" (thermomstat) I would buy a good automatic heater and convert it. Email me for details once you have bought one. Dave Dave Gomberg, Experimenta San Francisco CA USA gomberg at wcf_com