But the pump still needs to be connected to the boiler so the overurn is controlled (time or temperature.If it's an external pump then that's probably not the case
The existing cable could be used to power the pump and provide the required overrun..Pump is in airing cupboard next to control panel. Boiler is in outhouse some 20m away. Boiler has pump over run capability but not used as a few years ago, before I moved in, it replaced a really old boiler without overun and nobody gave it a thought.