If you are replacing an older model of boiler, the chances are that you will have a regular (or traditional) boiler.
Regular boilers are similar to a system boiler, since they heat your central heating and hot water cylinder directly. However, a regular boiler has all its major components separate from the boiler itself. For example, control valves, pumps cold feed tanks are normally found near the hot water cylinder making these boilers not as efficient as a system boiler. A regular boiler will still need separate major components and a cold feed tank.