Boiler Parts That Fail Most Often — Replacement Guide
Published: July 22, 2026 — BC Wide Home Services Ltd, doing business as BC Wide Heating & Air Conditioning — Greater Vancouver, BC
1. Expansion Tank — Most Common Failure
The expansion tank bladder fails after 5-10 years, causing pressure fluctuation and PRV discharge. Replacement cost: $250-600. Symptoms: pressure rises rapidly when the boiler fires, PRV drips water. This is the most common boiler issue we encounter.
2. Circulation Pump — Second Most Common
Circulation pump failures cause no heat. The pump may make noise, leak water from the shaft seal, or simply stop running. Replacement cost: $400-900. Grundfos pumps are the most common and readily available. Most replacements are completed same-day.
3. Zone Valve — Common in Multi-Zone Systems
Zone valves fail on the motor or the internal mechanism, causing loss of heat in one zone. Replacement cost: $300-600 per valve. If one zone valve fails, others in the system may follow — consider proactive replacement of all zone valves when one fails.