How to Test a Boiler Gas Valve — DIY Diagnosis

Published: July 21, 2026 — CANRO Heating & Cooling — Greater Vancouver, BC

Visual Inspection

Check the gas valve for: visible corrosion or rust, signs of gas odour (use soapy water solution on connections — bubbles indicate a leak), the valve lever moving freely (if applicable), and the valve coil connector being securely attached. A gas valve with visible damage must be replaced by a licensed gas fitter.

Electrical Testing

Using a multimeter, test the coil resistance across the two terminals on the gas valve solenoid. Compare the reading to manufacturer specifications (typically 20-200 ohms depending on the valve). An open circuit (infinite resistance) indicates a failed coil. Also verify 24V AC at the valve terminals when the boiler calls for heat.

When to Call a Professional

Gas valve testing and replacement should only be performed by a licensed gas fitter. If the gas valve is failing, it can cause dangerous gas leaks or improper combustion. Gas valve replacement costs $400-800 plus labour. Only use OEM replacement valves — aftermarket valves may not meet manufacturer specifications.

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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.