Vokera A07 fault

Vokera boiler A07 fault code meaning & how to fix

If you are experiencing not hot water or heating with your Vokera boiler and you are getting the A07 error message then we are here to help. One thing to note is that the unit will lock out when the fault A07 appears on the Vokera boiler’s screen.

The system will stop running and you will have not hot water or central heating until the problem is resolved. There are many possible causes for this fault, from minor malfunctions to serious internal damage and it is likely that you will need a heating engineer to fix it.

This article will explain what could have caused the A07 fault on a Vokera boiler means, and what kind of repairs you can expect to make your central heating and hot water work again.

What does the Vokera Boiler – A07 Fault mean?

Primary flow fault: Too high water temperature. The thermistor, a component that measures resistance in your boiler, sends them to the PCB (Printed Circuit Board), and uses them to determine the temperature in the system.

To diagnose and repair the problem accurately, you will almost always need a Gas Safe registered engineer.

The Vokera fault A07 refers to the thermistor in the flow tube. This is where water is carried from the boiler into the rest the house after it has been heated.

This part may also be called an NTC thermistor, which stands for Negative Temperature coefficient.

The PCB is the central control hub of the boiler and must be notified that every process has been completed safely and correctly before it can allow the next one to proceed.

If the PCB is exposed to temperatures higher than the safe operating temperature it will shut down and stop further heating and hot water.

This prevents internal damage from the boiler that could occur if it runs while overheating.

What Causes The Vokera Boiler Fault A07?

Limescale buildup on Heat Exchanger

Limescale is when minerals from the mains water supply get mixed together in your home when using your central heating and hot water. This can cause the A07 error codes.

This buildup eventually can cause damage to various fixtures in the pipes as well as the boiler’s internal parts. These problems are more likely to happen in areas with high mineral content.

Limescale buildup is especially common in the heat exchanger. This is the component that converts heated gas to heated water. It is a critical part of the boiler’s operation and can be overheated.

Hotspots are areas where scale accumulates. These hotspots can reach higher temperatures than other places. These hotspots can cause cracking by weakening the exchanger’s plate.

This is the most common source of boiler unit leaking and can lead to costly damage to the electrical components.

How to fix limescale buildup on Heat Exchanger

The extent of limescale damage will determine how a Gas Safe engineer will address this problem.

It is possible to remove limescale from major components if it is detected early. The specialist chemicals can be used to break down the deposits to give you a clean primary heat exchanger and carry the debris out of the pipes

This may be called a system flush or a power flush’ by your engineer. This service’s cost will vary depending on how large the system needs to be flushed. This is often determined by how many radiators are in the house.

An estimate of a household with six radiators would be between £320-£370 and you should ensure that you use a Gas Safe engineer

After this is done, you may be able to install a magnetic filter that will prevent any further buildup. This can be checked each time your boiler gets serviced.

These parts are typically installed during installation but can be added later if the unit’s location permits. Although the cost of these parts can vary depending on which brand they are, most often they cost less than PS150.

They are also a great investment because they can prolong the boiler’s life significantly.

The heat exchanger will need to be completely replaced if it has cracked from scale buildup. These parts can also be very expensive depending on the age and model of your boiler.

They are however one of the most costly boiler components, and you can expect to pay as high as £600.

An engineer will also need to determine if any leaks have occurred through these cracks. This will require an evaluation of the electrical components.

These may need to be repaired more expensively if they have been damaged by water.

Limescale buildup in Flow Pipe

The flow thermistor measures temperature in the flow pipe it is located in and not the entire heating system and can. be affected is the heating system water pressure is incorrect.

Limescale can build up around the thermistor and cause it to burn hotter than the surrounding waters. This can make the thermistor unable to take an accurate reading.

How to fix limescale buildup in Flow Pipe

Your engineer may be able to flush the system if limescale has not built up too much. These parts might need to be replaced if it has caused damage or corrosion to the pipe or thermistor.

These parts are inexpensive, with the thermistor being less than £30. Pipe spares are subject to change, but they will not cost more than £60.

System Blockage Is Affecting Circulation

Heat exchanger overheating can be caused by any blockage that prevents water from flowing freely which will affect the system water pressure.

This part will convert gas into heat, which will allow for the normal amount of water. However, if the temperature is lower, the heat will instead transfer to the surrounding boiler components including the exchanger.

Anywhere can experience a blockage, but the most common is the pump. It controls the flow of water through your system and all its moving parts must function freely.

Heating sludge is a common cause of blockage. This thick mixture is made when small pieces of debris and rust fall off the pipes. These flakes can congeal over time and clog parts like the pump.

Pumps can also have air locks. They may develop slowly over time, as air enters the mains supply or suddenly, when air is allowed in.

How to fix a system Blockage Affecting Circulation

Central heating sludge can blockage. This can be fixed with a flush using chemicals called central heating inhibitors.

Like limescale, the cost of this will depend upon the size and configuration of your heating system.

If the sludge has not damaged any components, then they can be cleaned and not replaced. An engineer might be able to install a magnetic filter that can prevent sludge buildup.

Engineers can also remove the air lock by bleed the entire system, including the boiler unit. This will cost you depending on the diagnosis and how much labour time is required.

Faulty Heater

This part may be taking incorrect readings and signalling to the PCB that it is operating at an unsafe temperature.

Fixing a Faulty Heater

The multimeter can be used by your engineer to determine if the thermistor has a problem.

It is possible to replace it for less than £30.

Faulty PCB

The A07 fault may occur if the PCB cannot receive temperature readings accurately or interpret them correctly.

This could be caused by loose connections due to vibrations in the boiler.

Moisture damage is a common cause of PCB malfunction. Even the smallest amount of water can affect electronic components.

How to fix a faulty PCB

Your engineer might test the PCB with a multimeter if all other causes are ruled out. It may be possible to repair the PCB if certain connections are loose.

The part is usually around £600 and will not be replaced. Without it, the boiler will cease to work.

Can I repair a Vokera Boiler A07 Fault myself?

This issue is not something you can solve on your own. It requires a diagnosis by a Gas Safe engineer of the boiler’s internal parts and can lead to serious damage if it isn’t addressed immediately.

If you haven’t done so in a while, however, you can still try to flush your radiators to get your central heating and hot water working.

An airlock can cause a problem in the circulation of the central heating system, but not the pump. Bleeding your radiators might be sufficient to correct the issue or if you have insufficient system water pressure you could try topping this up

Does the A07 Vokera boiler Error codes mean I need a new boiler?

One thing to check is whether your boiler is under warranty or not. Vokera boiler warranty generally isn’t that long, so if you have an older boiler, it may be more economical to invest in a new one. Another reason is that as time goes by older boilers become less energy efficient for heating and hot water which can cost you more on your energy bills.

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