Radiator knocking reduced after air and flow balancing
The sound occurred at startup and moved between radiators, pointing to system flow rather than pipe expansion at one location.
✓Contractor Confirmedrecorded confirmation level
01 / OBSERVED
→Knocking radiators when heating starts
02 / CONFIRMED CAUSE
→Air and unbalanced hydronic flow
03 / REPAIR
→The system was bled, pressure checked and balanced.
04 / VERIFY
Startup cycles became quiet and room temperatures stabilized.
WHAT CHANGED THE DIRECTION
The evidence that separated the cause
Supporting clues
- Startup trigger
- Sound moved through system
- Uneven radiator temperatures
Checks performed
- Cycle timing record
- Radiator temperature comparison
- System pressure check
Field lessonRecord when a sound occurs in the system cycle, not just where it seems loudest.
