egel: for some reason the central heating controller that most builders fit for new houses in UK is still rather basic, with a simple on/off timeswitch and on/off thermostats. Penny pinching, I suspect!
However, surely the *boiler* is always either on or off, and this discussion is about the *controller*. The advantages of a condensing boiler are a separate issue. The controller determines when the boiler is on, depending on the heating requirements, and may be anything from simple to sophisticated. The latter should be more efficient.
ds1: I would have thought that thermostatic radiator valves were for stopping a room getting too hot, not stopping it getting so cold it freezes? Anyway, if the rooms are not near freezing, there is no point in running the boiler at all, as it just heats water for no purpose, thus is inefficient.