Why is My Boiler Not Working?

There are many reasons why your boiler could start to malfunction or stop working altogether!

Unfortunately, you often only realise there is a problem when you don’t have hot water coming from your taps or heating in your home. Some of the causes of boiler breakdowns and inefficiencies can be long term issues that go undetected.

Also, many boiler problems first show themselves in the colder months. You may have only been using it sporadically – simply for hot water – without any problems. Then, when you need it to heat your property, your boiler goes on the ‘blink’!

It’s worth researching the reasons for boiler problems, even if yours is currently working fine. That way, if you do experience problems further down the line, you can pinpoint the issue and possibly brief a heating engineer quickly and efficiently. You can also spot boiler problems and get them fixed before your heating system stops working.

This guide to ‘Why is my boiler not working?’ will help you with emergencies and looking ahead to potential risks. Not least to make sure it stays energy-efficient.

Diagnosing boiler problems starts with looking at exactly what the issue is, then narrowing down the potential source.


No heat or hot water

This is probably the most common boiler problem. You suddenly discover that your water is running cold and your radiators are not heating up.

Is it just one radiator? See the section below on how to tackle this heating system problem.

If it is a system-wide failure, is your water pressure low? You can usually detect this boiler problem by checking a gauge on your unit. Some even provide a coded readout that highlights pressure issues. If your indicator is in the ‘red zone’, does your boiler have a simple lever or button you can use to ‘recharge’ the water pressure and get it out of the red?


If the pressure keeps dropping – cutting your heating off – it may indicate a leak in your system or some other issue that requires expert attention.

There are also other substantial reasons why your boiler is failing to heat tap water or radiators. These include a broken thermostat, diaphragm or valve, for example.

It is essential to use a Gas Safe registered engineer to find boiler problems and solutions when a new part needs to be fitted. If you use a credible engineer, they will also be honest in advising you whether your boiler is repairable, or it needs to be replaced due to excessive internal damage.


One radiator doesn’t work

If your boiler problem is localised to one or two radiators, for example, you may be able to sort it yourself. This involves ‘bleeding’ radiators, to release air pockets that are impacting on their effectiveness. It is something you can do with an allen key, inserted into the valve on each radiator unit.


Leaks and drips

Sometimes your boiler gives you clues that it’s malfunctioning, even when it is still heating water. The most common boiler problem in this category is having water escaping and pooling beneath.


Why is your boiler leaking?

There could be various reasons for this, but as the solution involves the components of your boiler pipes and valves, it is not something you should attempt to sort yourself. A Gas Safe registered engineer can look inside the workings of your boiler and identify the source of the leak, tightening or replacing components.

Incidentally, the problem could also be linked to the water supply to your heating system. For example, there could be corrosion in your water pipes or supply tank that result in dampness or water evidence around your boiler. A qualified and well-trained engineer will know how to follow the evidence to find the likely source of dripping, leaking or pooling water.

Another reason for boiler drips could be that your water pressure is too high. The force of the water strains your seals and valves. This may require a simple adjustment by the engineer. They can also check the pump seals and other parts of any residual damage.

In some cases, a leaking boiler is a symptom of the sort of damage that makes replacing the whole unit a necessary evil.

Help, my boiler is making strange noises!

Is your heating system banging, whistling or making strange gurgling and belching sounds? This can be worrying, even if your hot water and radiators are working fine.

The likely cause of a noisy heating system is trapped air or a problem related to water pressure. In some older boiler systems, there are creaks and groans that show it is straining to keep up with its tasks.

However, a noisy boiler could also indicate a serious issue is beginning to arise. It is recommended that you call in an engineer to listen and suggest a solution to your boiler problem.

This includes something referred to as ‘kettling’ when water in your system makes similar sounds to water in a kettle. This generally indicates limescale or some other contaminates caught in your system, reducing its efficiency. The water in your boiler could be overheating, causing it to bubble and hiss.

A trained engineer can flush out your heating system and make it fully operational and quiet!


Pilot light is out

The pilot light on a gas boiler is the small constant flame that ignites the heating function when you turn on taps or radiators. If it goes out, nothing happens!

Your boiler will feature a failsafe system to relight your pilot light, which could have been blown out by a draft of air, for example. Check your user manual for a guide to how to restart your boiler.

However, a failing pilot light could indicate a problem with the gas supply to your boiler, or to your whole property if other gas appliances are not working too. In which case, you must call out a Gas Safe engineer.

Thermostat not working

Another common reason why boilers stop working or become unreliable is a broken thermostat. This is the device that tells your heating system when to go on and off, and also establishes your preferred water temperature.

An engineer can usually replace this relatively quickly and cheaply. However, before you call them out, double-check that your boiler thermostat is set to the correct marks. It can be easily knocked out of sequence or deliberately changed by someone else, leaving you wondering, ‘Why is my heating not working?’.


Boiler keeps switching off

If you are wondering ‘Why does my boiler keep switching itself off?’ the answer is likely to be in one of the headings above. It is a safety feature of boilers, that indicates something like incorrect pressure or a component that’s broken.

Cold weather condensate pipe issues

Lastly, your answer may be outside! Some systems have a condensate pipe to take the waste moisture away. If this freezes over and blocks, your boiler can’t vent properly. This will usually result in an error code on your boiler. Thaw out the pipe carefully, to prevent it cracking, or call an engineer for a safe, quick solution.

In fact, using a qualified engineer is always a great idea, even if your boiler problem only requires a quick fix. It gives you peace of mind, and ensures you are not storing up small problems that could one day become a major heating system issue!


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