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Why is my boiler not firing up?

If your boiler isn’t firing up for central heating or hot water, it’s a serious problem that you’ll want to resolve as fast as you can.

Here, we look at the simple checks you can make, as well as some quick fixes you can try yourself.

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How to check why your boiler is not igniting

There are a number of reasons why your boiler may not be firing up, with many of them straightforward enough to resolve on your own.

1. Thermostat Setting

If the room’s temperature is higher than the thermostat setting, then your central heating won’t start up. Check the thermostat and increase the temperature if necessary. A temperature between 18-21°C is usually seen as the best setting.

To keep a closer eye on your temperature setting, it could be worth investing in a smart thermostat.

2. Fuse Box

If there’s no power to the combi boiler at all, but your other gas appliances are working fine, check your fuse box to make sure it hasn’t been tripped.

3. Boiler Timer

If you experience a power cut, you may find that your boiler’s timer has been reset, which will mean that it won’t fire up when you expect it to. To reset the timer, you’ll need to consult your boiler’s instruction manual.

4. Pre-paid meter

If your home has a pre-pay meter, you might want to check whether it has enough credit to allow the central heating to work.

5. Gas Supply

To make sure that it’s not your gas supply that’s causing the problem, check other appliances around your home, such as your cooker. If you do have a lack of gas, you should either contact your supplier or the Gas Emergency Service on 0800 111 999.

What could be the issues with the central heating system?

If you’ve checked the possible causes above and you still can’t get your boiler to ignite, then you might have a fault with your heating system.

1. The boiler pressure

Maintaining the correct boiler pressure is vital to keeping your unit working effectively. It should sit at around 1.5 bar for optimum efficiency, so make sure it is at the correct level.

Low boiler pressure (below 1 bar) means the unit won’t work. This could also indicate a leak, which could prevent your boiler from igniting as a safety measure. If you do uncover a leak, you should contact an engineer to book in a boiler repair.

If the boiler pressure is too high (over 2 bar), this can put a strain on the boiler and can result in a break down.

Luckily, an incorrect pressure setting is relatively simple to correct. Read our dedicated guide to find out how to correct your boiler pressure.

2. Frozen pipes

In the winter months, there’s a huge risk of your condensate pipe freezing, which could affect your hot water by preventing wastewater being disposed of down the drain. To prevent any further damage, your boiler may not come on until the blockage is cleared.

3. Air in the radiators

If only the bottom of your radiators are heating up, or aren’t heating up at all, then it’s likely that you have air trapped in the radiators, which can prevent water from circulating the system and lead to the boiler shutting off. Bleeding your radiators releases the trapped air, allowing the hot water to heat them up.

4. Blockage

Your boiler not igniting could also be the result of sludge in the pipes blocking the free flow of water. If your water isn’t allowed to circulate then the boiler may not ignite. A sign that this could soon happen is your radiators being cold at the bottom.

To prevent a build-up, it's recommended to have a magnetic filter installed. However, if you find that you already have a blockage, then you’ll need the assistance of a Gas Safe engineer to carry out a chemical flush on your system. Once the system is cleaned, then the magnetic filter should be fitted.

Boiler need some TLC?

Let our experts take care of it with an emergency repair

If your boiler isn’t firing up, you may need to seek help from an engineer.

Our Boiler Plan Gas Safe experts will point out any work that needs to be carried out, they'll also provide a fixed price repair quote.

With our 24 hour emergency repair and 95% first time fix rate, we’ll have your heating up and running again in no time.

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What are the common boiler error codes?

As well conducting these checks, you can also see whether you have a fault code appearing on the front of your boiler. This can give you an indication of the fault and, in-turn, the course of action to take.

You can find out what error codes refer to your boiler not firing up, as well as a range of other issues, by consulting your boiler manual or by checking out one of our handy fault code pages.

Vaillant boiler fault codes

Baxi boiler fault codes

Ideal boiler fault codes

Worcester Bosch boiler fault codes

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