6 Common Alpha Boilers Problems: Solutions and Troubleshooting

Alpha Boilers are pretty reliable but even they can go wrong from time to time. In this guide, we will highlight the six most common issues you are likely to encounter with an Alpha Boiler and explain how to fix them. Some of the fixes are DIY things, so you could end up saving a ton of money.

If you have a problem with your Alpha Boiler, you need to read this guide. While there are lots of potential causes for your problem, experience suggests that some issues come up far more regularly than others.

In this guide, we will outline the six most common problems that we have seen happening again and again with Alpha boilers.

We will detail what the likely cause is and how you can fix it. Some fixes will need a professional engineer, but others are things you can do yourself and this could end up saving you a fair bit of money on engineer bills.

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6 Most Common Alpha Boilers Problems

While Alpha boilers are usually fairly reliable, they can develop problems. In this section, we will take a look at the six most common issues we have encountered with Alpha boilers.

Your issue may not be covered here, and if not, feel free to message us with any questions you may have at the bottom of the page. But we are pretty confident that the majority of Alpha boiler issues will be covered by these six problems:

#1 – A Red/Yellow Indicator A Light

The most common issue we see with Alpha boilers is a red or yellow light showing on the display panel. This can indicate a number of different problems and both the colour of the light and whether it is static or flashing means different things.

In our experience, the most common light error to appear is what is known as a 47 fault code. This is when the A indicator on your display shows a solid red light. What this usually means is that the burner in the boiler has failed to ignite.

How to Fix it:

This fault can often be fixed quite easily by resetting your boiler. To do this on most Alpha boilers, you just need to rotate the switch on the front of the boiler to position 3. After about 30 seconds the boiler should then attempt to restart.

If the fault reoccurs or the boiler won’t ignite, it is likely that the problem is being caused by debris inside the boiler that is blocking the burner. You will need to get a qualified heating engineer to come and fix this issue, but it should be a simple job. The burner will need cleaning and the debris removed but it should then function properly.

If there is a more serious issue with the burner, it might need replacing. Be sure to get a quote for this before proceeding as it could end up being fairly expensive. It is possible that you might be better off investing in a whole new boiler, especially if your current boiler is old and has already had previous issues.

#2 – A Red Indicator A light And A Yellow Indicator B Light

If your Alpha boiler is displaying a red flashing light in the A indicator, and a yellow light on the B indicator, this means something slightly different.

It is again likely that the cause is that the burner has failed to light in your boiler, but the cause is likely to be something a little more complex.

How to Fix it:

Again, you can try to reset your boiler using the method above, but this is less likely to work in this instance.

Rather than a blockage, this error is more likely to be caused by a broken or malfunctioning burner. You will again need to get a qualified engineer to inspect your boiler and advise you of the issue and how to resolve it.

The worst-case scenario is likely to be that you need a new burner unless you engineer identifies any further underlying issues.

#3 – A Red Indicator A light

If your Alpha boiler is showing a red light on Indicator A but no light on Indicator B, the problem with your boiler is likely to be caused by an overheating thermostat.

If this is the case, your boiler is likely to also be displaying either fault code 2 or fault code 25. Your boiler will most likely then lockout as a failsafe measure too.

How to Fix it:

This is another issue that will require the help of a qualified engineer. There are a number of different issues that could result in an overheating thermostat.

Your boiler’s heat exchanger could have an airlock in it or there could be a blockage somewhere in the system. It is also possible that there could be a blockage or restriction in the flue or a fault with the flue sensor. There could also be a fault with the pump or the circuit valve could be closed.

None of these are issues which you can resolve yourself. You will need to get a qualified engineer out to run all the necessary tests to identify the problem and advise on the right fix.

#4 – Boiler Pressure Low

If you are finding yourself having to top up your Alpha boiler on a regular basis, it is quite likely that you will also be seeing an E10 fault code on your display panel. This is the error code that means your boiler is losing pressure.

When the E10 code shows, this means the pressure has dropped too low and it is quite possible that your boiler will lockout and stop working altogether as a safety measure.

When this happens, it is usually an indication that there is a leak somewhere in your heating system. This could be in the boiler itself but it could also be in your radiators or your pipework.

If you do have a leak, no amount of topping up will solve the problem until you fix the leak.

How to Fix It:

If you have a leak in your system, there are a number of ways it can be fixed.

Take a look at your pipework and particularly the joints to see if there is any evidence of water leakage. If so, seal the hole and then repressure your boiler and see if it retains pressure again.

There are also DIY sealants that can be put into your system which will fill any small hidden holes that you maybe can’t spot.

If you are unsure, it is best to get an engineer to help you with the leak rather than risk messing around with something you are comfortable with.

#5 – No Hot Water / Central Heating

If your Alpha boiler appears to be functioning properly but it is not generating either hot water or heating, the issue is most likely to stem from the diverter valve.

The diverter valve is the component inside your boiler which directs the hot water generated by the boiler to your radiators, taps and showers. If this valve becomes blocked or damaged, it can stop sending water to one system or the other, which is why you have hot water but no heating, or vice-versa.

How to Fix it:

If there is a blockage in your diverter valve, your heating engineer should be able to free this and clean up the component so it works properly again.

If the problem has damaged the valve, you will need to replace it and this can be quite expensive. A new diverter valve can cost upwards of £300 and there is likely to be labour costs on top of that.

If you have an older boiler that is out of warranty, you may well want to consider whether your money would be better spent on a brand-new energy efficient boiler instead.

#6 – Hot Water That Isn’t Hot

If your Alpha boiler is generating warm rather than hot water, you are not alone. This is a very common problem that can occur to boilers of any make or model.

The issue is likely to be one of two things; either a fault with the NTC thermistor or a build-up of limescale somewhere in your system.

An NTC thermistor is the component that monitors the temperature inside your boiler. This component is the bit that instructs your boiler to stop heating water when it has reached the desired temperature.

If the NTC thermistor develops a fault, it can send incorrect signals that shuts off your boiler before the water has heated up enough.

Limescale is another common cause of this problem. Limescale build-ups can happen in all central heating systems but they are most common in hard water areas. Limescale build-ups around components such as the NTC thermistor will stop them working properly, while you can also get build-ups elsewhere in the system.

How to Fix it:

You will need a heating engineer to resolve any problems with your NTC thermistors. They will need to open up your boiler and run some tests to identify the issue.

If there is a build-up of limescale, your engineer will be able to decide whether the affected components can be cleaned manually or whether a hot flush is needed.

A hot flush will push various chemicals around your central heating system that breaks down the limescale.

In the worst-case scenario, you will need to get a replacement NTC thermistor or even other components in your boiler.

Where to get a new boiler

If your Alpha boiler is old and out of warranty and your engineer is recommending fixes that will cost a sizable amount of money, you might want to consider investing in a new boiler rather than spending large sums patching up your old one.

If this is the case, we strongly recommend you get a quote from Heatable.

Heatable is an online installation company that offers some of the most competitive prices on a whole range of top quality boilers from all the major manufacturers.

Because they only operate online, Heatable has low overheads and is able to pass these savings on to their customers. They have plenty of special deals too, including extended warranties.

We always recommend you get a range of quotes before deciding on your new boiler. But, we do also suggest you make sure one of those quotes is from Heatable.


Alpha Boilers do go wrong from time to time. But when they do, the issue is usually a common one.

In this guide, we have highlighted some of the most common issues that can occur with an Alpha boiler and explained what is causing them. We have also explained how to fix these problems, either on your own or with the help of a qualified engineer.

Most issues are fairly simple to resolve but some can be caused by more serious issues that are more expensive to fix. If this is the problem for you, our advice is to consider investing in a new energy-efficient boiler instead. We have recommended Heatable as somewhere you should definitely get a quote from.

Have you had any issues with your Alpha boiler that we haven’t touched on in this guide?

Any other questions you would like to put to us? Do you have any tips for our readers that we haven’t covered in this guide?

We always welcome questions and comments from our readers, so please do share your thoughts with us today using the comment box below.

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