Why do I need a Room thermostat?
Jeff I’m a bit confused by the thermostat to be honest. That’s just going to feed back the temperature of one room to the boiler right? Can you explain how that helps given we have (9 rooms, 5-bed, 2-bath, living + kitchen)? Currently we end up “fine tuning” the rads in each room to suite our needs. Surely we’ll be in the same position with a single remote temperature sensor? There is always quite a big temperature difference between the ground floor and the third, usually around 3-5C, so I can’t see how we are going to be able to avoid setting each radiator separately. So I’m not sure what the thermostat will do for us.
The thermostat controls the boiler and turns the boiler off when the air temperature (yes recorded in one place usually the hall or lounge). The radiator valves do not control the boiler and at least one radiator should be on all the time (have no control). If all the radiators are off and the boiler is on you'll get boiler lockout. Overheating and shutting down, bad for the lifespan performance and efficiency.
Basically the roomstat and thermostatic valves are complementary.
If there are warmer spaces they can be controlled/limited via the thermostatic valves and the room stat used as an overall control.
Without a room stat people tend to heat the property until they feel it is too warm. The extra energy consumed to take them from comfortable to too warn is wasted.
Also see central heating principles and energy saving tips.