flexicom 30cx -no hot water?

Hi, my flexicom 30cx,approx 2 years old, was fine this morning, returned home to no hot water flow from any of the hot water taps. Switched on/off etc, swore and kicked it..still no hot waterflow.
Central heating fine and is working.I assume that as the boiler fires up and heats the water for central heating there is a problem with some kind of switch / valve that allows the water to be heated? Can you help please