With most systems there are lock shield valves which you can use to force water to other rooms.
The idea of a central thermostat is going out although I still have one. Using thermostatic radiator valves is the new way so each room is controlled independent.
They are not the answer to all problems one of the other common ideas is to use a thermostat with a timer built in so at different times of the day you get a different temperature. I use one of these around £25 and works well in my house.
But these can mess up when used together with radiator valves so it's not a case of one size fits all.
If there is a neutral at the room thermostat you could replace it with radio controlled type so effectively move the thermostat to any room.
So simple idea first on the hot rooms radiator there will likely be two taps. One with knob to turn it on and off and one without. The one without is called a lock shield valve and is used to balance the flow of water through the system.
What I normally do is first turn it off and allow at least the pipes feeding the radiator to cool. Once cool I turn it back on 1/4 turn at a time with around 15 mins between each turn and feel the pipes. As soon as one gets hot I stop. Now at around 1/2 hour between I monitor radiator heat. If too cold I open a little more.
This will mean water is pushed around the rest of house better. You then may find another room becomes the hot room. So you may need to repeat with another room.
Once done all radiators should get hot together each time central heating starts so room temperatures become more even.
If the bedroom radiator is hot but not putting enough heat into the room. Of course bigger radiator will help. But also spraying radiator mat black will help. May not look as good but look at any car radiator and what colour is it. Yes you have guessed it mat black. If you don't like colour at least spray the back of it.
Again simple methods often the best as well as making the bedroom radiator more efficient you can also make living room one less efficient. Stuff some material behind the radiator so reducing air flow around it.
Does that help?
