Sensowarm (?) heating systems for flats ... how do they work?

Question:i'm not sure if i've remembered the name correctly. it's a system where all of the boiler business is tucked away behind one of the radiators so it's good for flats with not much space. does anyone know what the name is and how they work? are they really dated now ... i couldn't find anything under any variation of the name when i googled it. thanks

Answers:
There are oil filled radiators that plug into electric, maybe that is what you mean?