I always fitted just green without problem.
They always came out that carped up it was difficult to tell what the original colour was anyway.
I always thought green for one type of valve and red for another?!?
The condensate trap forms part of the flue system.
You should not be
Advising on clearing it.
Attempting to clear it unless you are qualified and know what you are doing.
Sounds like either of the motorised valves.
Just because the radiators are not staying on it doesn't mean the ch valve can be eliminated if the microswitch is sticking inside the valve