Boiler Not Firing Up for Central Heating – Causes & Fixes

If you turn your boiler on and suddenly find that it’s not making the familiar firing up noise when you turn the heating on or run a hot tap, there’s certainly a problem.

There could be a number of reasons for the boiler not firing up, but before you call out the local plumber for professional assistance, it’s worth taking the time to try some basic DIY troubleshooting.

Please note: If you do suspect a more serious issue such as a gas leak or an issue with an internal component, such as the fan or pilot light, you will need to seek professional assistance and do not attempt to repair or tamper with the boiler yourself. Call your nearest registered Gas Safe Engineer for major repairs.

With that said, there could be a number of reasons why a boiler won’t fire up. In this post, we will provide some troubleshooting suggestions for boilers that are not firing up, as well as common error codes, their meanings and how you can potentially fix them (or if you require professional assistance).

10 Common Reasons for a Boiler Not Firing Up

1. No gas supply to your boiler 

It would be worthwhile checking if the gas supply coming into the property, either by attempting to turn on other gas appliances, such as a cooker, or asking if neighbours are having issues. If there is a local issue, contact the emergency gas service.

There are many potential causes of an interrupted gas supply including the supply being frozen by your supplier, as well as a frozen gas meter or pressure issues. In addition, if the gas valve is broken and in need of repair i.e. it no longer opens, then there is no way for gas to enter the boiler.

Common boiler error codes related to no gas supply: 

  • EA
  • E133

How to fix no gas supply to your boiler:

If your boiler is displaying a code related to no gas supply, then the first step is to check your payment meter. If you have no credit on the meter, the boiler will no longer be receiving gas, in which case the solution is to add more credit to your meter.

You may also want to ensure the gas meter is not frozen, if it is you will need to thaw it out and may want to insulate it to prevent it from happening in the future.

If you have recently had a new boiler installed, it may be an issue relating to the gas supply pressure. Some older boilers required a different gas pressure, so it may need to be tweaked by a Gas Safe Engineer.

If you need to reset your boiler too often, it may be a sign of a more significant fault, such as a faulty PCB, a boiler leak or a central heating pump problem, and if your boiler isn’t igniting, it may be time to consider getting a new boiler quote.

2. Boiler Pressure issues – too low or too high 

A boilers pressure will naturally vary when in use as heating water causes expansion which increases the pressure within the boiler.  A healthy, happy boiler will typically have a pressure of between 1 and 2 bars of pressure. Luckily most boilers feature pressure gauges to enable easy identification of the pressure levels inside the unit.

If the pressure is too low or too high the boiler will usually shut down whereas the consequences of high pressure inside the boiler are that the pressure release valve, or PRV, will release the excess water.  If this doesn’t happen the internal parts will fail.

Common boiler error codes related to boiler pressure:  

  • E78
  • E177
  • F1
  • CE 207
  • H07

How to fix no boiler pressure issues:

With a boiler pressure issue, there are steps that can be taken yourself to adjust the pressure on the system.  The pressure can be adjusted by the use of the taps, which are usually located underneath the boiler, however, always check with the boiler’s manufacturer manual the source of the taps and the process to make pressure adjustments.

If pressure issues are an ongoing concern in ageing boiler wear and tear on the internal parts may be taking place.  In this case seek the advice of a specialist engineer to review the boiler and advise if there are any improvements that can be made, or if it’s time for a replacement.

3. Boiler has no power

Modern boilers require electricity to operate and when they lose power they’ll stop working completely.

There are many possible causes of lost power to your boiler, but the most obvious is a local power outage impacting everyone in your area. Therefore, check your local power supplier for any relevant updates.

Another common reason is that a fuse has tripped either in your home or the boiler itself. Typically, any appliance with a broken fuse will not work for safety reasons, so if you restore your home’s power and still find the boiler not working it may need a new fuse.

Common boiler error codes related to a broken boiler fuse:  

  • E13
  • E317
  • F83
  • C1 264
  • FD 231

How to fix no a faulty boiler fuse:

The first step is to check your mains switchboard for any flipped switches, if there are any it may indicate a broken or faulty fuse, not necessarily your boiler but possibly. Next, restore power by flicking the power switch on.

Next, reset your boiler using the reset button and give the boiler time to reignite and power up.

4. Frozen condensate pipe

During the colder months, a common issue with boilers is frozen pipes. This issue is particularly frequent with condensate pipes which drain wastewater away from the boiler to an external drain, this means that a portion of the pipe is outside and exposed to extreme cold.

Boilers often have a safety mechanism built in to prevent the boiler from starting if it recognises that pipes are frozen.  Should the system pipes freeze, the quickest way to get back up and running is by applying heat sources to the area.

Often an error code will be shown that indicates a frozen pipe, but other common signs include gurgling sounds coming from the boiler itself.

Common boiler error codes related to a frozen condensate pipe:  

  • D5
  • E28
  • F1
  • F4
  • EA 229

How to fix a frozen condensate pipe: 

The first step is to deal with the frozen wastewater, which you can do yourself by thawing it out with warm water or a warm compression, such as a hot water bottle.

Once the pipe has been thoroughly thawed, you can reset the boiler and it should work normally.

However, if your pipe runs outside and is regularly going to be exposed to freezing temperatures, it’s a smart idea to insulate it. This is very easy to do using some insulating foam from your local DIY store.

5. Faulty Pilot Light – Flame Failure Fault? 

The pilot light is essentially where the flame to heat the water is produced and it is essential for boilers to function, however similar to the burner, the jet that a pilot light comes out from can become clogged with debris. An engineer is also required in this case to either clean the pilot light jet or replace it if needed.

Please note: A normal light should be blue, but if it’s not i.e. it’s yellow or orange turn off your boiler asap. This is a sign that the boiler is producing carbon monoxide, which is a lethal gas.

Common boiler error codes related to a faulty pilot light:  

  • 227 V , 228 V , 306 V , 2927 B, EA, F7, EA 227
  • F.27, F.29, F.88
  • E.04 – .10, E133, E128, E129, 3 Green Flashes
  • L6, LN, F2, FN, L2, L6

How to fix a broken pilot light: 

Unfortunately, the pilot light is located within the boiler case and any work involving gas must be carried out by a certified Gas Safe Engineer.

The engineer will turn off the boiler, open it up and examine the pilot light, diagnosing whether the issue is caused by debris, dirt or a fault, meaning that parts will likely need to be replaced. Of course, they will also check that the boiler is safe to use.

Is your boiler losing power? Or is your boiler pressure too high? If your boiler is old, past its warranty, it may be time for a new boiler replacement.

Other Common Causes of a Boiler Not Firing Up for Central Heating:


Airlocks can cause system performance issues with inconsistent heating with only parts of radiators getting warm or noisy pipework.  In this case, the first step is to bleed the radiators when the system is off and cool.

A bleed key will be required to loosen the nut at the end of a radiator, as well as a container to collect any water that is released when bleeding the radiators.  If you are unsure how to bleed radiators, try looking up a video on how to bleed radiators before you start.

Burner blockages

Sometimes a non-starting boiler can occur due to internal debris blocking the burner.  In this scenario, a specialised engineer will be required to clean the burner or replace it if damage has been identified.

Boiler error codes

Thankfully most boilers feature a display window showing the current boilers pressure bar reading and if there are issues, error messages will also be shown. Error messages can take the guesswork out of identifying the problem with the boiler.

Error messages are specific to the manufacturer and therefore it would be worth checking the manufacturer’s website to identify what the error code refers to.

Boiler not firing up the summary

There are a number of reasons that can result in a boiler not firing up.  Some basic issues can be checked yourself using the troubleshooting tips provided in this article, however, if there is any doubt regarding dragonising the concern or confidence to undertake the check, always call a qualified heating engineer.

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