There are several issues that could affect your boiler and cause it to stop igniting, such as faulty fan or gas valve, frozen pipes and others discussed in the following section. Try checking if your gas oven or hobs are turning on to check if your home has a sufficient supply.
No pilot light
If your boiler isn't igniting, it's likely that there is no pilot light. A common cause of pilot light going out is a blocked jet. Pilot light’s jet is small and can easily get blocked with even the slightest bit of debris. The good news is that the jet can be cleaned or easily replaced by a Gas Safe Engineer.
Your burner could be blocked
A burner can get blocked due to the production of carbon monoxide which occurs when a boiler burns gas. If your boiler’s burner is blocked, you have a couple of options to fix this issue depending on the burner's current condition. For a burner in a good condition, it may be possible to simply clean out the blockage, however, if the burner is in a bad condition, it is advisable to replace it completely.
A boiler fan extracts combustion gases from your boiler. If your fan is faulty, the boiler won’t ignite as a safety precaution. If you suspect that your boiler fan is faulty, it is important to not turn on the boiler and get it repaired as soon as possible.
Faulty gas valve
A gas valve is a device that allows gas to flow into a burner or appliance. If the gas valve is faulty or blocked, it may not allow gas to flow properly, which could stop your boiler from igniting. A gas valve that does not close properly can allow gas to escape, posing a fire hazard, contact an engineer to repair this issue as soon as possible.
If even the slightest bit of water is frozen in the pipes, it will block the pipes and the boiler will not ignite and be able to produce heat. To fix this, the pipes will need to be thawed. Once the pipes are thawed, the boiler should start working again.