I have a problem with my central heating system, its going into its 3rd winter its a worcester/bosch Greenstar 30CDi combi boiler, the main problem is the upstairs radiators seem to need constantly bleeding ( there are 4 upstairs) especially the radiators nearest and furthest the boiler. The downstairs radiators are fine (there are 3).As a aside the little pressure gauge does not appear to reading anything but I don't recall seeing it reading when the system was new.The other thing the electric thermostat at the bottom of the stairs does not seem adjusting any temperature.
My sister had this problem and it was only sorted when she called in the plumber and he completely emptied all her rads and flushed through some sort of cleaner as he said they're full of dirt and rust which accumulates over the years and stops them heating through prop.. He also said a lot of plumbers leave the cleaner in but you really should have the plumber back to empty it all out and then re-fill them with clean water.. As I say she has had no prob since - this was done about 4 years ago..
Just went back to boiler with a clear head I discovered there is a little tap on the bottom of boiler which when I turned increased the pressure on the gauge, I set in the green and bled out radiators and it seems perfect fingers crossed.