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Last Updated on January 23, 2021

Boiler Not Firing up for Central Heating – It Won’t Ignite – What To Do?

Zac Houghton

Zac Houghton

Heating expert and founder of Loftera.

Boiler not firing up for central heating or hot water? We’ve all been there and we know it can be super frustrating. Being without heating or hot water for more than a few hours can become a huge inconvenience for everyone in your household, not to mention a potential drain on energy without any of the benefit, depending on what the problem is.

With that in mind, we thought we’d put together a quick post detailing a few reasons as to why your boiler won’t ignite and how you can hopefully resolve this issue.

Boiler Not Firing up for Central Heating

Table of Contents

Quick answer: call an engineer

You might be hoping to avoid calling someone out for repairs at all costs, but the fact of the matter is, any gasworks should be handled by a qualified engineer verified by the Gas Safe Register (1).

Chances are, whatever repairs need to be made are not something the standard layman would be knowledgeable/comfortable enough to handle, and no matter how much you fancy yourself in terms of DIY, safety is the priority and an engineer is the only person who can guarantee that. Don’t take any risks where you don’t have to.

Possible causes

Now, while we will always recommend getting a professional in to sort any boiler issues, it always worth trying to diagnose the problem as best you can, even if only to make life easier for the engineer/technician themselves. Here a few common causes of when a boiler won’t fire up.

1. Tripped/blown fuse

It might sound like too an easy answer and you’ve likely already checked your fuse box/circuit breakers, however, many people forget this simple first step. Fingers crossed your problem doesn’t go any further than this and it’ll be an easy fix.

2. Pilot light problems

Pilot light on your boiler not firing up or going out repeatedly going out? The likelihood is that there is debris blocking it. As the jet for the pilot light is small, it only takes a little bit of dirt to block things up. This is one thing that, if necessary, you can attempt to fix yourself.

First things first, turn off the gas supply valve, then remove the pilot light assembly and thermocouple, which will allow you to clean the pilot light safely. Once you’ve done this, simply clean the jet with a compressed or a wire brush.

As always, if you aren’t comfortable doing this, then just get an engineer to do it for you: one of the benefits of calling out a professional is that they will spot/ be able to test for other problems you won’t. Alternatively, buying a replacement should be relatively cheap – either way, this should be a relatively easy fix.

3. Faulty gas valve

The gas valve controls the flow of gas into your boiler and given regular, daily usage, it can often result in a number of different faults. Whether it’s blockages and obstructions within the pipes, or a problem with the wiring, these simple problems can stop the flow of gas from entering your system.

As with all of the issues we’ll discuss, these are easily diagnosed by an engineer and given they involve both gas and electricity, it is important that you only allow a professional to do this work. If the issue is related to the gas valve, it’s likely because it has been incorrectly adjusted and has therefore locked out the boiler to prevent any excess gas leaking into the system.

3. Low pressure

Another job for an engineer: when completing any call-out, a boiler technician should ideally test the gas meters measuring the flow in and out of your boiler. This is one of the easiest ways to identify any problems with your gas supply and minor issues are often found during routine annual checks.

Once again, your boiler meters monitor the amount of gas flowing in and out of the system, and will lock out if there is too little/too much pressure. Fortunately, if this happens to be what’s affecting your boiler, there will usually be a fault code displayed on the control panel.

A good tip is to make sure that your pipes, meters and regulator are all insulated – regulators can tend to seize up during the colder months, so lagging/insulating should help to avoid this.

4. Blocked/ broken burner

Similar to the gas valve, the burner itself can also run into blockages, as well as suffer wear and tear. Cleaning out any build-up should hopefully allow your boiler to light, but if the burner is in poor condition or broken, replacement parts can be costly. It may be worth looking into a whole new boiler to avoid recurring repairs that could become more expensive in the long run.

5. Electrode/ignition lead problems

Hearing clicking, tinging or banging noises? An electrode and/or ignition lead fault could be the source of your boiler trouble. This noise is created by either of these parts faltering and, therefore, the boiler intermittently igniting and going out.

Your engineer will be able to test whether either of these parts have a fault but keep in mind, these parts a relatively cheap, so it may be more affordable to replace them altogether.

6. Issue with the fan

Whether your boiler’s not firing up for hot water or heat, be sure to check the boiler fan, as it is effectively one of the first links in the chain.

Boiler fans are essential in ensuring that leftover/harmful gases are vented into the flue and released safely. Therefore, if the fan isn’t working, the boiler will lock out to prevent any danger and subsequently not refuse to ignite.

You should be able to hear the fan when running your boiler, so if this isn’t the case, then it very well could be the root of your problem. Whilst electrodes and ignition leads are relatively cheap, replacement fans are fairly expensive; if the engineer says they can be fixed, we would certainly recommend this as opposed to outright replacement.

Final thoughts

Whatever your problem might be, any decent engineer will be able to resolve it and bringing one in will early will save you time and money. Here’s hoping your boiler trouble isn’t too serious and limited to as few instances as possible – either way, we hope you found this post helpful.

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