Boiler Expansion Tank Replacement — Cost and When It Is Needed
Published: July 22, 2026 — BC Wide Home Services Ltd, doing business as BC Wide Heating & Air Conditioning — Greater Vancouver, BC
Signs of Expansion Tank Failure
The boiler pressure gauge rises rapidly when the boiler fires (from 1 bar to 3+ bar), the pressure relief valve discharges water frequently, you hear water hammer or banging in the pipes, the boiler short-cycles, or the tank feels completely full of water (tap test — should sound hollow on top).
Replacement Cost
Expansion tank replacement costs $250-600 including the tank ($80-200 for standard 2-5 gallon tank) and labour ($150-300). Larger tanks for bigger systems cost more. The system must be partially drained. Adding an isolation valve allows easier future replacement.
Emergency Replacement
A failed expansion tank can cause the PRV to discharge continuously, flooding your mechanical room. We provide emergency expansion tank replacement. Same-day service available. Our technicians carry replacement tanks for all system sizes.