Most Common Biasi Boiler Faults And How To Fix Them

If you have a problem with your Biasi boiler, this is the guide for you. Take 5 minutes to read through the most common issues we have encountered with Biasi boilers. We will cover all the most common problems with Biasi boilers and could save you a ton on money on repair bills too.

Biasi boilers go wrong like any other brand, and it can be hugely annoying when they do and you are left with no heating or hot water.

There are lots of different things that can go wrong with a Biasi boiler but in our experience, some issues are far more common than others.

In this short guide, we will outline the five most common issues that we have seen with Biasi boilers and explain how you can fix them. We can’t promise to solve your problem, but there is a good chance. And some of our faults have DIY fixes that could save you money too.

It is possible that the fix you need is an expensive one. If this is the case for you, and your boiler is already old and out of warranty, you will want to consider buying a replacement instead.

We recommend that you check out the online installation firm Heatable. They offer some of the lowest prices on a wide range of boilers from all the top manufacturers and have some terrific special offers available too.

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The 5 Most Common Biasi Boiler Faults

#1 – Ignition issues

If your Biasi boiler won’t fire up, it is likely that there is a problem with the ignition.

This could be caused by a number of different things. It could be that there is a problem with the fan and your boiler is unable to remove the dangerous gases that can build up inside any boiler safely.

There could be an issue with the burner, such as a blocked jet or a debris build-up which is preventing your boiler from igniting properly. Or there could even be an issue with your gas supply, such as a problem with the gas valve.

How to Fix it:

Fixing your ignition issue could be straightforward but identifying the precise cause of the fault is much harder.

This means you will need the help of a qualified engineer who can diagnose the nature of the problem and fix it for you.

One likely clue will be the error code that your Biasi boiler is showing on its display panel. For example, if it is showing an ER 01 error code, this will signal a burner fault while an ER 05 will mean a fan fault.

You might be able to use these codes to identify the issue yourself but you will be best to get an engineer out to fix the issue anyway.

None of these issues should prove too expensive, but if you engineer says you are facing a bill of £500 or more and your boiler is already old and out of warranty, we would suggest you give serious consideration to investing in a replacement boiler

#2 – No Hot Water

If your Biasi boiler isn’t generating any hot water, the most likely issue is with the diverter valve.

A diverter valve is the component that sends hot water generated by your boiler to where it is needed. If your diverter valve has a problem, this can result in no hot water, no heating, and even cause your radiators to warm up when you are using your hot water.

Over time, diverter valves can become stiff or get blocked up by debris. This can result in them becoming stuck one way or the other.

How to Fix it:

This is another problem that you will need to call out a qualified heating engineer for.

They will be able to take apart your boiler and assess the diverter valve. If it is stuck or blocked up, your engineer should be able to clean and repair it.

But if there is a more serious problem, it is usually best to replace the valve entirely.

#3 – Red And Green Lights Flashing On Display Panel

Different Biasi boilers display errors in different ways, so if your boiler is flashing both red and green lights at the same time, it is a good idea to check your boiler manual to see what this means.

With most Biasi boilers, flashing red and green lights usually indicate one of two things. It is either a problem with the boilers fan or an issue with the air pressure switch.

The fan is an essential component that takes dangerous flue gases away from your property. The air pressure switch is a sensor that makes sure that the fan is doing its job properly.

Because venting flue gases is a major safety issue, your Biasi boiler will flash red and green lights if it thinks this isn’t being done properly.

How to Fix it:

The first step is to see if the fan is still operating properly. You can usually do this by touching your boiler. If the fan is operating it will be vibrating slightly and you should also hear a gentle humming noise

If the fan is working, hopefully, the problem is with the air pressure switch. You will need a qualified gas engineer to test for this. Replacing this component is not very cheap, but less expensive than the other possible issue which is with the printed circuit board (PCB).

Your Biasi boiler’s PCB is the motherboard of your boiler and if this has gone wrong, you are looking at a bill of in excess of £500 for a replacement. If your boiler is an older model and out of warranty, we would strongly recommend that you consider investing in a replacement boiler.

If you do this on a site like Heatable, you will spend less than you might think and in the long run, you are likely to end up saving money.

#4 – Water pressure problems

If there is a problem with either the water circulation or water supply to your Biasi boiler, it is likely to show error code ER 04 on the display panel.

This error is fairly common and is usually caused by a lack of water pressure. This can be as a result of either a leak or a problem with the pump.

How to Fix it:

If the water pressure is too low, you will be able to tell by looking at the pressure gauge. For most Biasi boilers, this should be set at around 1.5 bar. If it is lower than this, you can top it up using the external filling loop.

Topping up will solve the problem temporary, but if the issue reoccurs, it is likely to be caused by a leak somewhere in your boiler or central heating system. You will either need to identify and fix the source of the leak yourself or call out an engineer to help you.

If the pressure seems ok, it’s likely that the fault is being caused by a problem with water circulation. Circulation problems with Biasi boilers are almost always caused by a fault with the central heating pump.

Pumps are difficult and expensive components to fix and you will need to get an engineer to take a look. If your pump is just blocked up with debris, he might be able to clean it out for you. But there is a good chance you will need a new pump and these do not come cheap.

#5 – Banging Noises And Not Working

If you have an older Biasi boiler, it is not unknown for them to develop strange banging noises. This is especially common when they first fire up.

The most common error code that accompanies this noise is ER 01 and it usually means there is a problem with the burner.

This problem can be caused by blocked jets or a build-up of carbon, but it could also be to do with the ignition, the wiring, the ignition lead, or even the printed circuit board (PCB).

How to Fix it:

This is another one that will need the help of a qualified gas engineer. They should be able to identify the cause of the problem fairly quickly.

If it is caused by a blocked or clogged burner or ignition, they will be able to clean this out and get things working again. They will then reset the boiler and see if things are working again.

If it is a more serious issue, you might need a new burner, ignition, or PCB. These can vary in price but a new PCB will cost you a minimum of £500 and if your Biasi boiler is already old and out of warranty you will want to give serious consideration to investing in a whole new boiler instead.


Biasi boilers do go wrong and in this guide, we have identified the 5 most common issues that we have seen with them. We have also advised you on the best way to fix these problems.

Some of our fixes as DIY things you can do yourself. Others require a qualified engineer. If your need to replace a major component, you might want to consider replacing your whole boiler as this can work out cheaper in the long run. We have recommended you get a quote from Heatable if you plan to do this.

Do you have a problem with your Biasi boiler which isn’t covered in this guide? Any questions for us we haven’t addressed in this guide? We always try and respond quickly to any comments and questions left by readers, so please do share your thoughts with us today using the comment box below.

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