There are lots of different types of Electric Boilers and they can all directly replace a normal Gas boiler. There is even a Combi Electric boiler to replace a Combi gas boiler.
Sizes Range from 2kw to 12kw . More than one can be fitted in parallel to increase the heat output.
The only requirement is a dedicated electric feed direct to the consumer unit. All the other components of your existing gas system can be reused.
There are many advantages to a Electric boiler
They are more efficient (around 99.8%) than the best condensing boilers, therefore offsetting some of the usage cost.
The usage cost can be offset further by have PV Panels installed or other micro generating projects running.
The is no vent or chimney required, so if you are upgrading an old boiler you will not be forced to reposition it to an outside wall.
These boilers come in many different shapes and sizess allowing a much greater choice in the location, for example located in the Airing cupboard next to the hot water tank or an under stairs cupboard
No Servicing required as they have no moving parts. As long as the central heating system is inhibited the heat exchanger to should last a very long time.
No gas certificate required. This makes them an excellent choice for landlords.