The air causes loud noises in radiators, heat exchangers, pipes and pumps. It makes it extremely difficult to adjust systems and it promotes corrosion, and thus, the formation of dirt and magnetite. Air in the system leads to a significant reduction in heating and cooling performance, premature wear and tear on major system components, or, much worse, a blockage.
This, in turn, could lead to a complete failure of the system and all the hassle that comes with it, such as dissatisfied consumers and residents. If a system is designed and operates without an air removal solution, it becomes much easier to predict how the system will perform in the medium to long term future.