What does air in a hydronic water system cause?

Air in a hydronic water system can lead to several issues, including reduced efficiency and uneven heating. It can create air pockets that block the flow of water, causing some areas to be less heated or even cold. Additionally, trapped air can lead to noise in the system, such as gurgling or banging sounds, and can contribute to corrosion over time. Regular bleeding of the system is essential to maintain optimal performance and longevity.