F83 Vaillant fault code

What does Vaillant boiler F83 fault code mean?

According to Vaillant, the F83 fault code relates to the return temperature sensor detecting insufficient temperature increases, after the burner has been lit.

Vaillant boilers will display a fault code when there is a problem with their boilers and central heating systems.

This allows you to diagnose the issue or call a local professional boiler repair service. There are many fault codes that boilers can experience. These range from simple blockages to maintenance and lockout issues.

This article will take a closer look into the Vaillant F83 fault code. It can be fixed by you or a qualified professional depending on what the fault code is referring to so you may not need a new boiler just yet.

What is The Vaillant F83 fault code?

This is a common problem with boilers, and should not be a concern. However, it must be addressed in order to ensure your boiler works at its best to heat and provide hot water. Vaillant boiler fault codes will be displayed for many reasons.

Vaillant F83 error is used for their ecoTec plus models.

F83 is a fault code that indicates that the boiler detected an inexact temperature change in the return and flow pipes after it was lit. There are many reasons for this warning code, including incorrectly calibrated thermostats or faulty wiring.

Low boiler pressure

Low pressure can cause problems therefore is this is the reason for the fault then you can fix it yourself. However, generally, this f83 error will not be fixed without the assistance of a Gas Safe Engineer. It may also require parts replacement.

Return temperature sensor faulty

The return temperature sensor of your water may not have been calibrated correctly or maybe incorrectly positioned inside the pipe. This is an indication that your boiler system has low pressure. This F83 error code could also be caused by a problem with the wiring or a loose or damaged connection to the PCB. Loose connections can easily be fixed by a boiler engineer.

Faulty heat exchanger

Another reason could be that the boiler has an issue with its heat exchanger mechanism. This can lead to low temperatures. It could also be caused by a malfunctioning gas valve, low gas flow in the system, or a problem within the combustion chamber. This can lead to heat transfer being too low or restricted.

Incorrectly adjusted gas valve

If they are damaged or worn out, the parts can be replaced easily. If you have an incorrectly adjusted gas valve then this can be easily and quickly adjusted. A faulty gas valve will however need to be changed.

A complex error code such as F83 on the Vaillant boiler means that the problem lies within the boiler and should be addressed by a qualified Gas Safe registered boiler repair technician.

The F83 error code does not necessarily mean your boiler is broken. It may just be displaying because parts or sensors aren’t working as they should. This could cause your boiler to stop functioning properly. A replacement boiler may be necessary if the problem is due to an internal leakage within the boiler. Otherwise, it will likely keep showing the same code.

How to Fix an F83 Error code

Because new thermistors are not equipped with fresh wires, it is important to test all wiring around these parts for any faults or damage. If the wiring is the problem then you will need to replace the thermistor.

Low pressure can be caused by a problem in the boiler or heating system. Low pressure can also occur due to a leak within the boiler or in the pipework.

You may be able to spot a leak yourself but a Gas Safe Engineer should be called in to fix it.

How do I know if my Vaillant boiler needs to be repressurised?

The boiler’s screen shows the water pressure. If the water pressure sensor says it is too low, the boiler should be repressurised.

How to top up the pressure on a Vaillant boiler

You will find the filling loop under your boiler. It is a silver Flexi pipe with one or more taps.

The right-hand tap should be turned until it is aligned with the pipework. Keep an eye on your pressure gauge and open the left-hand faucet to let water in the boiler.

Do not let the pressure rise too high. It should be around 1.5. To prevent accidental pressure rises, ensure that both taps have been closed after the pressure is balanced.

TheVaillant ecoTec Plus models have a built-in filling loop. There are two small taps under the boiler. After the pressure has rebalanced, open both taps and close them again.

Is an F83 Sign of a Broken Boiler?

F83 could indicate that your boiler’s NTC thermistors need to be replaced or that some wiring needs to be replaced. However, it does not necessarily mean that your boiler has reached its end. However, this fault could be triggered by damage to the boiler. This could lead to the need for a replacement boiler.

What do I need to reset my Vaillant Boiler after an F83?

After resolving the problem, a Gas Safe Engineer will reset the boiler for you. To determine if the problem has been resolved, you can repressurise your boiler and bleed it.

What is the cost of fixing an F83 fault?

Repairing an F83 might require the replacement of the NTC Temperatures and/or wiring. This is a relatively inexpensive repair in terms of the parts. Although labour costs can increase the cost, unless it is a faulty heat exchanger, this is one of the most affordable errors for a boiler engineer to fix.

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