Gas Valve Failure: Why a Solenoid or Gas Valve Leaks or Will Not Open

Valves Used in Gas Appliances

Symptom 1: Valve Will Not Open

Symptom 2: Valve Will Not Seal (Internal Leak)

An internal leak is the most dangerous valve fault because the appliance can still appear to function: the FFD may show a flame, the operator sees a normal burner, but gas continues to a closed or adjacent circuit. This is exactly why internal tightness is measured separately in F2, not inferred from the valve clicking closed.

Symptom 3: External Leak

• Leak at the body seal, diaphragm or gasket, often after a pressure or temperature cycle;
• Leak at the fitting to the valve, caused by under-torque or a damaged flare;
• Cracked or porous body from a defective component.

External leaks are caught by the external-tightness gate and can be located with bubble solution; an internal leak is invisible to that test and needs the downstream check.

Why Valves Fail: Cleanliness and Incoming Parts

Many valve failures are cleanliness failures. A particle of metal, seal material or debris in the gas path can lodge on the seat or bind the spool; a dry valve stored for a long time can open stiffly on first energising. This is why the gas path must be kept clean during assembly, incoming valves should be controlled by part and batch, and the gas supply used in testing must be filtered. Repeated failures in one position point to a supplier or component batch rather than workmanship, while a single random stuck valve is usually contamination. Ageing, voltage drift and thermal cycling also weaken coils and seals, so a valve that passes at assembly should not be assumed to stay perfect without an endurance or ageing check.

Testing the Valve on the Line

1. Measure coil resistance and insulation, then energise and confirm the valve opens at the defined voltage;
2. Record open and close time (linked to the FFD timing in F1);
3. Check internal tightness (no gas through a closed valve) and external tightness (no leak at the body);
4. Repeat over several cycles to catch intermittent sticking;
5. Log action, timing and tightness against the serial number.

Dedicated solenoid valve test equipment measures the electrical and sealing characteristics of the valve itself, while a gas cooker test bench verifies the valve as it behaves in the appliance. A valve that will not open produces an ignition failure (F4); one that will not close creates the CO and gas-fill risk in F5.

Incoming Inspection, Batch Traceability and Voltage

The cheapest place to catch a bad valve is at incoming inspection, before it reaches the appliance. A simple incoming check for coil resistance, pull-in voltage, external and internal tightness, and a number of open/close cycles separates a defective batch at the goods-in point and lets the factory return it to the supplier instead of reworking finished cookers. The valve part and batch should be recorded so that a field failure can be traced to the supplier and the production date; without that link, a repeated valve fault cannot be separated from an assembly error and the same batch can silently reach the line again. A defined incoming limit, based on the component specification rather than on a single good sample, prevents the limit from drifting with a convenient supplier.

Voltage deserves attention on export lines. A solenoid rated for one supply voltage can behave differently on another, and low or unstable supply voltage produces a weak or intermittent opening that looks like a mechanical fault on the appliance. Coil and supply should be confirmed together, and where a valve is used across markets with different electrical arrangements, the correct coil variant must be fitted for the destination rather than assuming one part suits all. Keeping the coil variant, valve batch and appliance destination on the same record removes most of the late “valve works at the factory, fails abroad” complaints that are otherwise the hardest to reproduce, and it gives the export team a clear answer when a distributor asks which valve and batch were fitted.

Common Mistakes

• Hearing the valve click and assuming it seals, without an internal-tightness check;
• Replacing the control board when the real fault is a stuck spool or a dead coil;
• Testing the valve once and missing intermittent sticking on later cycles;
• Ignoring cleanliness and an unfiltered gas supply that contaminates the seat;
• Not measuring pull-in voltage, coil resistance or closing time;
• Treating a repeated position failure as workmanship rather than a component batch.