Ah but, the more radiators you have in use, the more quickly the water cools, so the more work the boiler has to do to keep it at a constant temperature. Basically your rooms get heated by heat transferring from the hot water to the surrounding air, so wherever a room gets warmer, more enrgy is being taken from the hot water, so boiler does more and you pay more.

So it would be cheaper to switch off some radiators in the loop. Also look into getting thermostatic controls for each of your radiators. These go in place of the normal tap, but close off when the radiator gets hotter than it needs to. Means you don't have to rely on a central thermostat, and can have different rooms at appropriate temperatures - nice and cosy in the sitting room, cooler in the kitchen and so on.

it will have numbers on M ..........

yeah the thermostats do...and then I have on the opposite side another thing I can turn and it's that which confuses me...lol

ohhh it's like a 'heating master class' huh...lol

i think thats the valve.........don't mess with that LOL

you might get wet LOL

mind you rads should be aired after the summer i bet you all know that anyway ...they will run more effienty with no air in LOL