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If your boiler won’t turn on, you could be left without heating and hot water until the issue is resolved. We understand that this can be a real nuisance for the whole household, so we’ve put together this guide to help you find the problem and work out how to fix it.
There are several possible issues that could prevent your boiler from igniting. We’ll look at each of these in turn over the course of this guide. As well as helping you to identify the problem, this post also explains some common tricks you can try before calling an engineer.
Never attempt to mend any part of your boiler on your own. If you suspect that your boiler has a fault, you should always call a Gas Safe-registered engineer to take a look. Find an installer to fix your boiler. Alternatively, visit our boiler repair page for more information.
There are a range of reasons why your boiler might not be turning on. Here, we’ve explained the possible options starting with those which occur most often.
The most common cause of a boiler not igniting is that your home has already reached the temperature you’ve set on the thermostat. If the temperature is set to 18°C and your thermostat shows that the house is at 19°C, the boiler won’t come on as your home has already been heated to the requested temperature.
Don’t worry if this is the case – just set the desired temperature to 20°C (i.e. above the current temperature in your home) and you should find that your boiler turns on. If this doesn’t work, then read on to learn more about the other problems that could be preventing your boiler from igniting.
Your boiler needs electricity to ignite. In many cases, our engineers find that a boiler not coming on is a sign of an electrical problem (and nothing to do with the appliance itself).
Do the other parts of your home still have electricity? If the lights and electrical appliances elsewhere in your home aren’t working, it might be that you have a power cut (particularly if you’ve had heavy snow, strong winds, or other extreme weather conditions). In this case, your boiler won’t work until your electricity is up and running again.
Sometimes an overnight power outage can cause your boiler's programming to reset. This might change the time settings that control the appliance, preventing it from coming on as it should in the morning. If your boiler won’t ignite, it’s worth checking that the control panel settings are correct and as you’d expect them to be before considering any other possible issues.
A tripped fuse in your consumer unit could also be preventing your boiler from getting the power it needs. Find the consumer unit in your home and make sure that all of the fuses are switched on. Additionally, make sure the isolation switch next to your boiler is turned on.
Your boiler needs a certain gas pressure to run, therefore issues with your gas supply such as insufficient or no gas pressure can result in your boiler not igniting and displaying a fault code.
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.
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.
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.
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.
There are a few simple and safe boiler fixes you can do yourself before calling an engineer.
Attempting to fix a boiler issue yourself can be incredibly dangerous. Boilers contain high levels of heat and pressure, and can cause serious injuries if not handled correctly.
Additionally, if the boiler is not properly fixed, the issue could get worse, leading to even more serious problems. It is always best to call a gas safe engineer to fix a boiler issue, as they will have the experience and knowledge necessary to get the job done safely and correctly.
To mange and book your boiler repair appointments online, register your Vaillant appliance, and activate your smart home subscription, visit myVAILLANT Web online service appointment.
If you're looking to replace your boiler, check out ofFind a Boiler tool to find your new Vaillant heating system. All you need to do is answer a couple of questions and we'll help you find the perfect replacement.
