Lesson 8
Air in Systems
Spot where trapped gas sits in a radiator, bleed it safely, and know what it means when you keep having to.
Builds on
A radiator that gurgles
Sam’s bedroom radiator ticks and gurgles when the heating comes on, and the room never gets quite as warm as the others. Water in a heating system carries dissolved air, and fresh water brings more in. As the water heats and moves, some of that gas comes out of solution as bubbles, the way a glass of tap water left in the sun grows bubbles on its sides.
Bubbles that reach a radiator can collect in one pocket. Water can’t circulate through a space full of gas, so that part of the panel never gets the hot water and stays cold. The gurgle is water moving past the pocket.