The 6 Most Common Alpha Boilers’ Problems [And Quick Fixes]

Is your Alpha boiler acting up? This 3-minute guide will cover the most common Alpha boiler faults and, hopefully, help you decide whether to pay for repairs or get a replacement boiler.

Although we try to find fixes for all Alpha Innovation boilers, those raising the most questions are the CB24, CD28X, Intec 28X and CD28C. So, where possible, we included boiler issues that are common on these models specifically.

#1 – Red (A Indicator) Light Is On

The biggest problem with Alpha boilers is red/yellow lights appearing on the display. Depending on which light is flashing and how will determine what the problem is.

Either way, there’s a good chance you’re seeing a 47 error code displayed on the boiler panel.

When the A indicator is a solid red, this indicates that the burner has failed to light.

The Fix

For a simple reset, Alpha recommends rotating the switch on the front of the boiler to position 3 (reset sequence).

After 25-30 seconds, the boiler will attempt to restart.

If the burner still won’t light or the burner output is insufficient, there’s a good chance it’s blocked with debris. Get a Gas Safe engineer to inspect and clean the burner. If the burner needs replacing, it’s worth getting a quote for the replacement. But, if your boiler is old, out of warranty and costing huge amounts in repair bills, it might be worth getting a quote for a new boiler.

#2 – Red (A Indicator), Yellow (B Indicator)

The scenario is different when the red flashing light is the A indicator, and the yellow is on the B indicator. 

This indicates that the burner has failed to light.

The Fix

When only the red light appears, the boiler can be reset by setting the dial to position 3.

However, there’s likely more to the fault than a simple reset; the problem becomes a little more complex.

The burner could be blocked with debris or faulty, or there could be an issue with the gas supply.

It’s advisable to have a heating engineer inspect the burner.

RELATED READING: Everything you need to know about boiler installation costs

#3 – (A) Indicator Flashing Red

If the (A) light is red, but the (B) light is showing nothing, the problem is with the overheat thermostat.

The boiler will show error code 2 or 25 and then lockout.

The Fix

You’ll really need to get a Gas Safe boiler engineer to help diagnose the problem.

It could be (but not limited to):

• An airlock in the heat exchanger
• Primary flow blockage
• Blocked or restricted flue outlet
• A fault with the flue sensor
• Pump fault
• The circuit valve for the heating is closed

A Gas Safe engineer will run the necessary visual and electrical tests to determine what the exact problem is.

#4 – No Hot Water

The current state of your Alpha boiler can say a lot about why it’s not providing hot water. For instance:

• Does it have power? Are the power lights on?
• Is the fan operating before the boiler tries to ignite?
• Does the boiler fire up?
• After firing up, does the boiler stay operational or cut out?

These are all separate issues. If your Alpha boiler problem is none of the above, there’s a good chance the diverter valve is to blame. The latter is an essential component in central heating systems with a combi boiler, as it allows the boiler to switch between heating and hot water modes.

This is emphasised more if you have no hot water, but your heating works.

The Fix

On some occasions, a stuck diverter valve can be freed. But, if your boiler (and, therefore, the diverter valve) is old, it’s worth considering a replacement part.

If the boiler is over 8-10 years old, due to the price of the diverter valve replacement (upwards of £350 including parts in many cases), a new boiler is a better option. We’d suggest getting on-screen prices from Heatable (no personal details needed and no “callbacks”).

#5 – Low Boiler Pressure

Are you constantly having to top up the pressure on your boiler?

If so, there’s a good chance that the Alpha E10 fault code is being displayed on your boiler’s display panel.

This fault code signifies that the boiler has lost pressure.

And, now the pressure is too lower for the boiler to operate safely.

In general, expect a lockout and E10 fault code to be displayed when the pressure drops to 0.6-0.8 bar.

Boilers that lose pressure link directly to a heating system leak. This isn’t always a leak on the boiler.

Everything from expansion vessels, pumps and radiators can leak. And a pressurised system will translate any loss of water into a loss of pressure.

So, you can top up the boiler’s pressure and reset it to clear the fault code. But, where is the leak? Depending on where it is, it could be causing damage to your property.

The Fix

We’ve created guides on boilers that lose pressure, as well as boiler leaks.

Read through those guides, and depending on the amount of pressure loss, you’ll have a reasonable route to fix the problem.

#6 – Hot Water Isn’t Hot!

Another common problem with Alpha boilers is hot water that, well, isn’t hot.

This isn’t just a problem that occurs with Alpha, but with all brands. The fault can usually be pinpointed to:

• NTC thermistor faults
• Limescale build-up

The NTC thermistor (or thermocouple) on your Alpha boiler monitors temperature.

As water hits the desired temperature (set by your thermostat), it tells the boiler to switch off or stop heating water.

If the NTC thermistor is faulty, it won’t be sending the correct signals. Water can get too hot, but typically, it fails to reach the temperature set at the thermostat.

If electrical tests show the NTC thermistor is working correctly, the likely cause is a hotspot on the central heating pipes.

Dents or bends can cause this in pipes or by centralised limescale build-up near the NTC thermistor.

The increased heat around the thermistor makes the sensor think the average temperature of the water is much higher than it is.

So, it shuts off the boiler before your hot water is actually hot.

The Fix

A boiler engineer will test the NTC thermistors to check they are producing resistance readings correctly.

If they are, limescale likely needs to be removed. This can be done by replacing sections of offending pipework or a hot flush.

Alternatively, if the build-up is on the thermistors themselves, these will need to be cleaned or replaced.

#7 – No Lights on the Boiler

If you don’t see any lights on your boiler’s console, there’s an overwhelming possibility that there’s no electrical supply to your device. In this event, your boiler won’t ignite until the power is restored.

The Fix

Find out if the issue is isolated to your boiler or other appliances as well. Check the circuit breaker to see if any of the switches are in the off position. If you find that other appliances are running normally, and the power supply issue seems to affect only your boiler, it’s best to call an electrician to investigate the problem further.

How to Repressurise an Alpha Boiler

Here are the 4 easy steps to repressurising an Alpha combi boiler if you’re getting the E10 fault code:

1. On your filling loop, open the right-hand tap completely
2. Slowly open the filling loop’s left-hand tap while watching the pressure gauge
3. Keep the taps open until the pressure gauge hits 1 bar
4. Close both taps on the filling loop

The boiler should now be working normally — there’s no need to reset the device.

When to Replace Your Boiler

If your Alpha boiler is old, no longer under warranty or an adequate boiler cover plan, and you’re seeing frequent boiler breakdowns, you may be wondering whether you should repair or replace your appliance.

Both options can be viable.

Repairing a single faulty part in an otherwise healthy boiler makes sense — especially if you’re covered by a boiler warranty or a care plan. Conversely, sinking hundreds of pounds into a boiler that’s living on borrowed time is a waste.

In simple terms, you’re due for a replacement if any of the following are true:

• Your boiler is no longer under warranty
• You don’t have boiler cover
• The repairs will set you back more than £300
• You suspect that the boiler is on its last legs already

To help you arrive at an educated decision, we suggest you check out Heatable’s deals on Alpha boilers — these are some of the best Alpha prices you’ll come by in the UK. All you have to do is fill out a 90-second survey (no personal information required), to you’ll get a fixed quote on your screen. Once you see Heatable’s offer, you can decide if you’d rather repair or replace your faulty Alpha boiler.

FAQs About Alpha Boiler Issues

Below you’ll find our answers to a few common questions about issues with Alpha boilers.

Why does my Alpha boiler keep cutting out?

If your boiler keeps switching off, the 2 most likely causes are low water pressure or a thermostat that’s telling the boiler to shut off.

When the boiler pressure drops below 0.6 bar, you’ll find that the boiler will not be able to operate. In most cases, there will be a leak somewhere in the central heating system; you’ll need a heating engineer to fix this leak and repressurise the boiler before it can operate normally once again.

In the event that your Alpha boiler keeps cutting out despite being in the normal pressure range, you should get a boiler engineer to check the thermostat. It’s possible that the thermostat is faulty, and sending wrong commands to the boiler.

How do you adjust the pressure on an Alpha boiler?

To raise the pressure, you’ll have to use your boiler’s filling loop; you can read more about this procedure here. And if you need to lower the pressure, you can simply bleed a radiator until the pressure returns to normal levels.

Note that both of these actions should only be undertaken once you’ve eliminated the root cause of the boiler’s pressure issues. To learn more, please read the following guides:

• Low boiler pressure
• High boiler pressure

How do I reset my Alpha combi boiler?

To reset your Alpha boiler, you can turn the switch at the front of the boiler to Position 3. This will start the reset sequence, which may last as long as 30 seconds.

Note that you should only attempt resetting your boiler once you’ve resolved the root cause behind the boiler fault.

Alpha Boiler Still Not Working?

Thanks for reading our 3-minute guide to the most common Alpha boiler problems and fixes.

Sick of your Alpha boiler and want an upgrade to a high-quality Worcester boiler installed instead? Visit Heatable and get your fixed-price boiler quote online.

What’s Next?

Did we omit your Alpha boiler error in the post above? Please leave us a comment below, and we’ll answer as soon as possible.

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