There could be several reasons why some radiators are hotter than others in the home. It might simply be the case that certain radiators have higher heat outputs than others.
Or, if you know the radiators to have identical heat outputs when working properly, it is likely that trapped air is present in the colder models, which can lead to reduced heating efficiency.
The solution is to bleed the colder radiators, which can be done relatively simply by following the steps in our guide on how to bleed a radiator.