Boiler Water Hammer — Causes and Fixes for Vancouver Homes

Published: July 21, 2026 — BC Wide Home Services Ltd, doing business as BC Wide Heating & Air Conditioning — Greater Vancouver, BC

What Causes Water Hammer

Water hammer in boiler systems is caused by: trapped air in pipes creating shock waves, expansion and contraction of pipes rubbing against framing, or a sudden stop of water flow when zone valves close quickly. It is more common in systems with iron pipe or copper pipes that are not properly anchored.

DIY Fixes

Bleed air from all radiators to remove trapped air. Check that pipe supports and hangers are secure — pipe rubbing against joists or studs creates noise. Insulate pipes where they contact framing. Reduce boiler water temperature slightly — lower temperature reduces expansion noise.

Professional Solutions

If DIY fixes do not resolve water hammer: install air elimination devices (air scoop or Spirovent) to remove micro-bubbles, add water hammer arrestors near zone valves, or install pipe expansion loops. A technician can identify the specific cause and recommend the most effective solution.

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Safety Reminder

If you smell gas, suspect carbon monoxide or believe there is an immediate danger, leave the property and contact emergency services or the appropriate gas emergency authority. Do not remain inside — exit the building immediately and call for help from outside.