Air rises to high points; where a pipe run traps it with no escape, the bubble can resist water pressure enough to stop flow, particularly in low-pressure hot water systems. In drains, trapped air causes gurgling and slow, surging flow.
Supply air locks are usually purged by flushing; drainage air problems point back to venting design.
Describes trapped air interfering with flow in pipes.
High points of supply pipework and unvented sections of drainage.
A CCTV drain inspection is the standard way to confirm whether this is what's happening in your pipes: the camera shows the condition on screen, a locator pinpoints the exact position and depth, and you get a recorded report before any repair decisions are made.
A CCTV drain inspection shows exactly what's happening inside your pipes — no guesswork.