Gas Control Valve Failure on Water Heaters — Signs and Replacement

Published: July 20, 2026 — CANRO Heating & Cooling — Greater Vancouver, BC

Signs of Failure

A failing gas control valve shows: no hot water despite pilot being lit, pilot not staying lit, water temperature fluctuating, burner flame yellow or lazy, gas smell near the valve, or error codes on electronic valves. The valve controls both gas flow and temperature regulation.

Diagnosis

A technician measures: gas valve output voltage (should be 24V at the valve solenoid), thermopile millivolt output (should be 300-750 mV), and continuity through the valve safety circuit. Electronic valves require diagnostic code reading.

Replacement

Gas control valve replacement costs $300-600 including parts and labour. On older water heaters (10+ years), consider replacement instead of valve repair — the valve cost is significant relative to a new water heater.

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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.