If your boiler is not firing up, this can be a big problem in your home, especially if you are left without hot water or heating in the colder UK months. With this in mind, if you have an awareness of some common faults that could be the reason why your boiler won’t fire up, you could fix it yourself if it is a minor problem or be able to give a professional engineer an idea of the problem when they come to repair it.

In this article, we are going to take a closer look at some potential causes for why your boiler isn’t starting up like it should. This should give you a clearer insight into what the issue is, the severity of the problem, and how it can be fixed.

What are some common faults that can prevent your boiler from firing up or there is no ignition?

Blocked burner

When a boiler is on and burning, it generates carbon dioxide, if this CO2 gas blocks the burner, the flame will become inconsistent. This will result in you not having heating or hot water. A sufficient clean of the carbon build up should resolve the problem, but you may need to replace the burner if there is any indication of damage.

The fan has a fault

If you have been recently using hot water or heating you will notice the fan beginning to operate after. The purpose of the fan is not for cooling down the boiler but to generate a draught that will keep harmful gases away from the boiler and push them into the flue. From there the gases can be safely transported out of your home.

If the fan is not working properly, the boiler will not ignite and instead lockout. In situations like these it is not advisable to turn on the boiler as it could be dangerous. You should contact an engineer to come and check the fan.

Lack of gas pressure

Sometimes, there can be a lack of pressure in the boiler which leads to it not being able to fire up. To determine exactly what the problem is, the gas pressure must be tested. It could be that your boiler only doesn’t ignite in the winter, in which case the gas meter may be the root cause. This is because gas meters can become frozen at low temperatures.

Problems with the gas valve

The role of the gas valve is to control the supply and flow of gas. So, when the boiler requires more heat to function effectively, the valve will automatically open to provide more fuel. If your boiler is not igniting, it is possible that the valve is blocked, seized, or there is damage to the wired connections.

No pilot light

If your boiler is not igniting and the pilot light has gone out, it typically means debris has blocked the jet. Even the smallest amount of dirt can get into the jet and make the pilot light go out and lead to the boiler not igniting again and potentially needing to be replaced.

Your pre-paid meter has run out of credit

If you have a pre-paid meter fitted in your property and it is not topped up with credit, your boiler won’t ignite. In this case, there is likely no technical fault with your boiler.

Fuse box has been tripped

The boiler itself might be working properly but the main fuse box has tripped and as a result the boiler won’t fire up.

Frozen pipes

If they haven’t been installed correctly, pipes have a tendency to freeze in severe weather conditions, which could stop the boiler from firing up. The condensate pipe goes from the boiler to the outside wall and the extra liquid produced by condensation deposits here. When the weather is cold, even the slightest amount of water can freeze and cause your pipes to block.

Trapped air

The term ‘bleeding’ refers to letting the air out of the radiator and central heating system in your home. If your boiler is not igniting, the likelihood is that air is still trapped in the central heating system and hence the radiator will not be operating efficiently either. Bleeding your radiators will get rid of pockets of air that are stuck inside the heating system and make your boiler functional again.

Low thermostat

The boiler might not fire up if your thermostat is set too low. Your heating system won’t kick in until the temperature of the environment is lower than the temperature set on the boiler. You can solve this issue by increasing the thermostat.

Electrical fault

Even though a boiler is a gas appliance, it also has some electrical components and if you are having problems with your boiler an electrical fault could be the cause. Electrical energy is needed to operate the boiler in the same way a car requires a battery for ignition before it uses fuel. An electrical fault may be down to a faulty plug or a blown fuse, but you won’t be able to identify this problem on your own. It is essential that you contact an experienced engineer to check the boiler for electrical faults. Don’t try to repair it yourself.

why won't your boiler fire up?

Are there any basic fixes you can try before calling an engineer?

Whilst there will be some serious problems that can only be repaired by a professional, some smaller faults you might be able to fix yourself to get your boiler operational. Here are a few things to try if your boiler is not firing up as it should:

Double check the basics

Start with the basics when seeing what is wrong with your boiler such as ensuring that you have enough credit in your prepaid meter, check if your other appliances that function with gas are working normally, and examine the fuse box to make sure there are no tripped switches.

Reprogram in case of a power cut

If you have recently experienced a power cut, it is likely that the timer of the boiler has reset itself. When this occurs you simply need to reprogram it with the right time zone, and it will begin working again.

Look at the pressure gauge

You should check the pressure gauge of your boiler if it won’t fire up. If it is displaying one bar or less, the pressure is low. By increasing the pressure, the boiler will start up again. When the indicator is showing below one it means the water pressure is too low. To get the pressure back up, look for the filling loop that is normally located at the bottom of the unit. It is important that when you are changing the pressure, you have turned off the boiler first. Open the valve and you will hear water filling into the system which should increase the pressure indicator. As soon as the pressure gets to 1.5 you can close the valve and turn the boiler back on.

Increase the thermostat

If the thermostat is less than 21 degrees, it could prevent the boiler from heating your home. Turning the thermostat up to higher than 21 degrees should start the boiler working again.

Reset the boiler

In some cases, all an appliance requires is a simple reset, there may not be any breakdowns or mechanical faults. Your boiler might just need to rest for a minute or two. Try turning off the power supply and waiting about 60 seconds then turn it back on again and hopefully your boiler will fire up as normal.

Bleed the radiators

To carry out this repair you should first turn off your central heating system as all radiators need to be cool. First, attach your radiator key to the valve, then take a piece of cloth and turn the key anti-clockwise slowly. You should hear a hissing sound which means the gas is escaping from the radiator. When the noise stops and you are done, close the valve again.

When should you contact a Gas Safe registered engineer to fix your boiler?

Boiler repairs are not easy, and you won’t always be able to ignite it with the quick fixes above. If you have tried these repairs and they haven’t fired up your boiler, don’t touch any other part of the boiler or central heating system. It may be time to contact the experts.

You should get in touch with a Gas Safe registered engineer if you experience the following issues:

Pressure problems

Boilers operate on pressure, if the level of pressure is not balanced, the boiler won’t work properly. When there isn’t enough pressure, the boiler will fail to provide enough heat and hot water to the house. If the pressure is too high, your boiler won’t be able to thoroughly heat the water, it will just put pressure on the parts. To find out if your boiler is not working because of a pressure issue, check the pressure gauge. The gauge should not be below or above the green zone when the boiler is off, nor should it be in the red zone.

Water leaks

When there is a leak somewhere in the boiler or heating system, the pressure will start to drop. Look out for dripping water underneath the boiler and pipes.

There isn’t any power

If the boiler is not firing up and you have attempted to reset it several times, it is likely due to an electrical problem. For example, it could be that the circuit board is down. You won’t be able to fix an issue like this on your own, a professional engineer will be able to inspect the boiler and diagnose the problem.

potential boiler faults and their fixes

Don’t try to repair the boiler yourself

It may be tempting to try and fix your boiler yourself as finding a reliable engineer that is free to come out can be time consuming. This is why a lot of homeowners attempt to make repairs themselves. However, trying to do so could make the problem worse and in some cases, cause injuries as well. Below are just a few reasons why you should avoid doing big fixes on your boiler.

Gas boilers can be dangerous

It is against the law to conduct repairs on gas appliances if you are not a Gas Safe certified engineer. If you are not qualified you won’t have the knowledge and experience necessary to carefully deal with gas related issues. Unqualified repair attempts could lead to gas leaks, carbon monoxide exposure, and in more severe cases, cause explosions. Carrying out repairs yourself on a gas boiler is not safe for you or anyone in your household.

It invalidates boiler warranty and home insurance

All boilers come with a warranty from the manufacturer and for extended cover you may have taken out home insurance. If you end up tinkering with the boiler, you will invalidate the cover as well as the warranty. Even opening up a boiler is classed as working on the appliance. So, don’t try to touch the body of the boiler and call an engineer to carry out inspections.

You could cause more damage to the boiler

Most people won’t know what they are doing when it comes to trying to fix a boiler. Therefore, it is better and safer to let a professional handle the job. An expert will have knowledge of how the internal parts of a boiler function and have years of experience dealing with different types of boilers from different brands. Unless you are well versed with the inner workings of a boiler and all of its elements, you could end up making the problem worse and damaging the unit altogether.

As we have seen, there are a wide range of various reasons why your boiler is not firing up from insufficient pressure to faulty valves, frozen pipes, and more. Sometimes you might be able to fix the issue on your own, other times you will need to call in a professional. In these cases, you should always choose a Gas Safe certified engineer with insurance to complete the work.