how to fix baxi 105e c/h fault?

hi guys /girls,
i have just fitted a new diaphragm in differential valve then put it all back together, the boiler works fine ,there is hot water,the temp for the rads is up to 80c ,pump is running ,there is no air from auto vent but hot water not reaching rads,it is a if there is some restriction to flow pipe,any help would be much appreciated,thanks