Your Gas Hob Is Not Lighting Properly Or Staying On

Not being able to light your hob is undoubtedly a major problem: how can you prepare and cook all your delicious dishes if it will no longer work? But no need to panic. Instead, find out about the various issues that can cause this problem.

THE POSSIBLE CAUSES FOR THIS FAULT:

• The gas jet is blocked

• The thermocouple is defective

• The valve is in the "low" position

• The air flow is not properly adjusted

• The openings on the burner crown are obstructed

• The openings on the burner crown have water in them

• The spark plug is split or broken

• The spark generator isn't working

• There is air in the hoses or pipes

• The safety cut-off on the pressure regulator has been activated

WARNING
Before doing any work on your appliance, make absolutely sure you disconnect it from the power supply and switch the gas supply off at the valve.
There is a risk of receiving an electric shock.
Wear suitable protective gloves if you need to dismantle anything.
There is a risk of getting cut or injured.

The gas jet is blocked

The gas nozzle (also known as a jet) may the part that's causing your hob to no longer ignite. Spilt or boiled-over liquid (e.g. milk, water, etc.), or liquid left behind after cleaning can actually block gas jets. When this occurs, a spark will be generated as normal but the gas won't be able to reach the burner, which means there will be no flame.
To get access to the jet and unblock it, first remove the burner crown and flame cap. To clean it out, simply use an ordinary toothbrush or, if the jet is too blocked, a fine needle.
Tip: be very careful not to enlarge the hole in the jet when unblocking it. It is made to a very precise diameter, and this is key to it operating correctly. Unless it's too badly blocked (such as by carbonised sugar for example), there shouldn't be any need to replace this part.

The thermocouple is defective

A thermocouple is a kind of safety device found on most makes of gas hob. It works by ensuring that a flame is actually being produced by the ring. If the flame goes out (for whatever reason), it will cease to come into contact with the thermocouple, which will then close the valve on the burner. If you press the ignition button for more than 10 seconds to get the flame going, then, when you release the button, the flame goes out, the thermocouple probably needs replacing. Check the condition of the small rod next to the burner crown: it should be neither distorted, broken nor worn, and the flame needs to be coming into constant contact with this part. In the majority of cases, it's the thermocouple that needs to be replaced when this type of fault occurs.

The valve is in the "low" position

The valve on each ring can be adjusted by means of a special low flame/simmer adjustment screw. This enables you to set the rate of gas flow when the knob is in the minimum position (i.e. when the flame is at its lowest: the setting used for simmering). If the "low" position provides too weak a flow of gas, the ring ignition system will not function properly, or may even not work at all. Ensure, therefore, that the low flame screw is correctly adjusted, turning it clockwise to reduce the flame or anticlockwise to increase it.

The air flow is not properly adjusted

Some burners (mainly those on older generation hobs) are fitted with an air collar that allows you to adjust the amount of air mixing with the gas. If this collar is not correctly positioned, you may not be able to ignite your burner. As well as ensuring a flame is actually produced, the right gas-air mixture also stabilises the flame and prevents it from giving off smoke. To obtain a flame with these characteristics, therefore, the rate of air flow must be properly adjusted. To carry out this adjustment, simply reposition the air collar.

The openings on the burner crown are obstructed

As you already know, the flame you require for cooking purposes emerges through the openings in the burner crown. However, if these openings get blocked by dirt or fat, for example, the flame will not be able to pass through them, i.e. it will get smothered. To resolve this problem, simply unblock the openings using a fine-pointed tool such as a toothpick.

The openings on the burner crown have water in them

Has your burner crown recently been cleaned or had water spilled on it? If so, it's very likely there is still water in its openings and this is what is preventing the ring from lighting. As it happens, this is very easy to fix, with no major work required: to get everything functioning properly again, simply leave the burner crown to dry properly.

The spark plug is split or broken

The spark plugs on gas hobs, which are often composed of ceramic and a piece of metal, generate the spark that serves to ignite the flame. Without this spark next to the burner, it would not be possible to produce the flame. If the spark plug is melted or broken, the spark will either not be produced, will be too weak, or will not be generated in the right position. In all these cases, the spark plug will fail to ignite the gas. You can easily check the condition of the spark plug: simply look to see if it has any splits or cracks or if any of the ceramic has chipped off. If it does have any of these issues, you will need to replace the spark plug in question to get the ring working properly again.

The spark generator isn't working

The spark generator supplies the spark plug with the electricity it uses to produce the spark. If the spark generator on your hob is no longer working, none of the spark plugs will produce a spark, and as a consequence, no flame will be produced. All the rings will therefore be affected by the same ignition issue. You will need to replace the entire spark generator, as it is not possible to open them up in order to locate the exact cause of the problem.

There is air in the hoses or pipes

If the rings on your gas hob have stopped working after the hose or gas bottle has been replaced, or after you have just moved into a new house/flat, it is very likely you have air in the hoses/pipes. This excess air will prevent the flame from igniting. So you will therefore need to purge the pipes/hoses. To do this, turn on your largest ring and leave it on for several seconds to allow the air to escape from the pipes/hoses. Test afterwards by lighting the smallest ring. Warning: if you smell any gas whatsoever when doing this, turn the ring off immediately.

The safety cut-off on the pressure regulator has been activated

Inserted inside gas bottles, pressure regulators serve to reduce the pressure of the gas as it leaves the bottle and enters the hose. On modern pressure regulators, manufacturers have added a safety device that prevents accidents by cutting off the gas if the hose is suddenly ripped or pulled off (such as if you move your cooker a little too forcefully, for example), or if there is a major leak. Each time the bottle is replaced or the valve is opened or closed, you need to either press the button or move the lever to release the safety cut-off.