Designer radiators come powered by either a central heating system or connection to a mains electrical circuit. It all depends on the radiator in question and the technology and design that it uses.
When the connection is made via an electric plug socket (or outlet) all that is required is the plugging in of the appliance. This is no different to plugging in a kettle or a TV. However, if the radiator requires hard wiring this is a job for a qualified electrician and it should not be attempted by a novice.
If, as is more probable, the radiator connects to a central heating system powered by a boiler, the job is one for a plumber or heating engineer and not someone who dabbles with DIY.
Connecting a new radiator to a central heating system can be fraught with disaster for anyone who is unsure of what they are doing. If you make a mistake, then you could end up with serious water damage and this will more than exceed any anticipated savings that doing the job yourself may have offered. There is also the possibility that you may inadvertently damage your expensive designer radiator.
The best solution is to employ the services of a qualified plumber who will be able to drain the system, or disconnect the flow, from the supply leading to the radiator during fitting. He or she will also be able to ensure that the radiator is correctly filled with water and that any air is removed from the system. Radiators also require balancing at the valve and this is something that an experience plumber will do far more efficiently than a novice.
Most designer radiators come with their own thermostatic controls, however if you have purchased a bathroom towel rail, many of which are now sold at budget prices, this may not be included. If this feature is absent your plumber can easily fit a thermostatic valve to the radiator and this will give precise temperature control within the area that the radiator services.
Like all skilled trades, plumbers and electricians are not cheap and many will have a minimum call out charge to cover their time and costs.
Fitting a single radiator is not of course a big task, however your tradesman probably has to schedule it into a morning or afternoon and you may therefore be charged for that period of time. (Remember this includes travel, use and wear of tools etc.) The point is, if you have put time and money into selecting a feature radiator you do not want to risk damaging it, or your property, by trying to install the radiator yourself.