Why are your pipes making loud noises when you turn on thermstat for heat?

Loud noises from pipes when you turn on the thermostat for heat can be caused by several issues. One common reason is the expansion and contraction of metal pipes as they heat up, which can create banging or clanging sounds. Another possibility is trapped air in the system, leading to water hammer or knocking noises. Additionally, sediment buildup in the boiler or pipes can cause irregular water flow, resulting in similar noisy disturbances.