Boiler flames

Why won’t my oil boiler fire?

If your oil boiler is not firing up, or firing but then cutting out soon after, you may have a problem that is known as oil boiler lockout. Read on to discover what this means, what could be causing the problem and how you can solve the problem as quickly as possible.

What is oil boiler lockout?

Your oil boiler is designed to automatically shut down or ‘lockout’ if it detects that there is a fault in the system (usually via the flame sensor). This happens when the sensors detect that the fault could cause damage to internal components and/or present a safety risk if the boiler were to continue operating. If your boiler is in lockout mode you may see an error or fault code on the display panel or a coloured flashing light confirming this.

What causes oil boiler lockout?

Common causes for oil boiler lockout include:

  • A leak in the system causing low boiler pressure
  • A fault in the thermostat, e.g. a problem with the radio frequency (RF) pairing which means that the boiler does not know when to fire up
  • The fan which works with the flue to expel harmful fumes from your home may be broken, which will cause the boiler to lockout for safety reasons
  • The air pressure switch, which detects whether the fan is operational, may be broken and causing the boiler to lockout for safety reasons
  • The printed circuit board (PCB) which controls all of the different components may be faulty. This can be hard to diagnose and will require investigation by a trained engineer

How to fix oil boiler lockout problems

Check if a fault code is showing

Each boiler manufacturer and model has its own series of fault codes. These can often identify the cause of the boiler lockout so you can decide whether or not an engineer is needed. If you have the boiler handbook, this should have a troubleshooting guide explaining the different fault codes. If you don’t have a copy of your manual handy, you should be able to find it online. For Worcester Bosch boilers, you can search for manuals online here.

Check that you have not run out of oil

Remember that sometimes the simplest solution is correct - it is possible that you may have simply run out of fuel. Check the level of oil in your storage tank either with an electronic gauge or by using a ‘tank-stick’ or ‘dipstick’ (just as you’d check the oil in your car). If you have a low oil level in the tank, it may not be enough to fire the system. It is fairly common for oil tank gauges to get broken or stuck with age, so this may be why you have experienced the problem.

Check the boiler pressure

If the boiler pressure is too low or too high then the boiler may lockout and you will need to adjust the pressure before you reset the boiler. Oil boiler pressure should usually be around 1.3 bar depending on the model, but generally all boilers should be between 1-3 bar. If the pressure is too high, you may need to bleed water from the radiator bleed valve or the drain cock. If it’s too low, you will need to use the boiler pressure gauge to increase it. If you find that your boiler pressure is regularly dropping, you may have a leak which you will need an OFTEC registered service engineer to fix.

Check the condensate pipes/vents

If you are experiencing boiler lockout during cold weather, it is possible that the condensate pipe/vent which enables the harmful fumes to escape your home have frozen shut in cold weather. If this is the case, check our handy blog here on how to fix a frozen condensate pipe.

Try resetting the boiler

When the boiler locks out it will automatically cut off the oil supply as part of the safety mechanism. If you have oil and everything appears to be in order, try resetting the boiler. It’s best to consult your boiler manual for how to do this but it is usually a simple operation.

If these steps don’t solve the issue and your boiler keeps cutting out, you may need to contact a professional heating engineer to diagnose and fix the problem. Your boiler may need a service which includes cleaning dirty filters, removing airlocks and cleaning blocked nozzles. In some cases, there may be a more severe problem which will require replacement parts or even a boiler replacement.

Safety first - only attempt to carry out basic maintenance on your oil boiler such as restarting it or adjusting the pressure as instructed in the user handbook. Never attempt to perform any other repairs. Instead, always contact an OFTEC registered heating engineer.

Looking to replace or service your boiler? D.R. Plumbing & Heating have been serving the North Wales region for over two decades and specialise in gas and oil boiler installation. We enjoy a reputation for our friendly, professional and prompt service along with excellent workmanship. Call today to book a free, no-obligation quote. If you would prefer us not to visit you at home, we can also assess your boiler and prepare a quote by video call.

Call now on Wrexham 01978 291 923 or Mold 01352 620 125.

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