I have a 3 story house with a cellar. The combi boiler is on the 1st floor. The radiators get hot on the ground floor and the 1st floor but don't get hot on the 2nd floor and the cellar, only the pipes get hot, until the thermostatic valves on the other radiators start cutting the radiators of on the 1st and ground floor. Then these other radiators start getting hot.
I've bled the radiators already but makes no difference.
Does any one know the cause? could it be that the pump isn't powerful enough?
