As said with electric it is simply a fan heater, as with any fan heater it is the fan which is most likely to fail, so it needs some safety system to ensure the element switches off should the fan fail, normally a thermal fuse, which is not really a user replaceable part so the better the fan the longer it lasts.
My Myson is also hydraulic i.e. a heated liquid is circulated from a central liquid heating device. I normally call it a boiler, however if it did boil the water I would need to get it repaired or replaced. I use water but it could be any liquid worked in one place where it used oil and a water and inhibitor mix is quite normal. hydraulic is in my dictionary. I will guess it is a Latin word so likely a few different spellings.
The Myson I use is in the living room, there is a variable speed fan set to a slow speed because of the noise. During the day one does not hear it running, but at night when ambulant noise is low then it seems very loud and we have to turn up TV volume to compensate. It is now 30 years old so has stud the test of time. However the fan has stopped and I have needed to add a drop or two of oil through the years to get it running again. If it had been electric it would have blown the thermal fuse so would have likely been thrown out.