Is your Vaillant boiler displaying the F83 fault code? Here we explain the most common causes and potential fixes.
Boiler companies tend to include boiler codes as part of their boiler model programming.
These codes are designed to inform users when there’s a problem with their boiler or/and heating system.
Vaillant’s boiler manual tells customers what the nature of each issue is and explains possible solutions.
Some Vaillant faults have one likely cause while others may be the result of several potential issues.
Moreover, whether or not a Vaillant error code can be solved DIY or if you need to hire a qualified heating engineer will depend on the code in question and the actual cause(s).
But, what about Vaillant’s F83 fault code in particular?
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What Does F83 Mean?
The Vaillant F38 fault code means your boiler is detecting a temperature change in the flow and return pipes that is not as it should be.
This occurs after your boiler is already lit.
The F83 Vaillant error code applies to Vaillant ecoTec Plus models in particular.
Causes of Incorrect Temperature Change
There are several possible explanations for an F83 fault, namely:
Not enough water in your system
Having enough water flowing through your heating system’s flow and return pipes is necessary for your thermistor to pick on temperature changes accurately.
However, even though low pressure can contribute to an F83 fault, it unusually isn’t the only factor.
Since heating systems see a reduction in pressure as time passes, your heating system can lose water as a result. A leak is also a potential reason for this issue.
Heat exchanger has a low heat input
Without the correct amount of heat in your heat exchanger, your boiler will not be able to heat the water in your system correctly.
Thermistors need recalibration
Another potential cause of an incorrect temperature change relates to the NTC thermistors of both the flow and return pipes.
This is because, if they are not calibrated as they should be, their resistance readings may be rendered incorrect.
Connection issues
Last but not least, it’s feasible that the wiring between the PCB and thermistors has an issue (e.g., they are loose or simply damaged).
Communication between these two components may be cut off completely or even made intermittent.
You may be interested in Gas Engineer Allen Hart explaining the most common boiler problems and how you can resolve them in the video below:
Can I Fix an F83 Fault DIY?
Whether or not you can fix a Vaillant F83 error by yourself would depend on the nature of the issue.
Low Pressure - Possibly, Yes
If low pressure has caused the problem (as could be the case where there is insufficient water in your system), you could top it up DIY.
Repressuring your boiler is one possible solution, but you may also need to bleed your radiators. If you’re unsure what to do or lack any suitable skills or knowledge, it’s best to hire a professional.
Other Cause - No
For any other issue, such as a leak (another possible reason for insufficient system water), the low heat input into the heat exchanger or thermistors that need recalibration, you’d need to hire a qualified heating engineer.
Most work involves a boiler or heating system but be dealt with by a Gas Safe Register engineer both legally and for safety reasons.
This is for good reason. After all, DIY accidents cost the NHS around £200 million in 2019.
And DIY gas accidents are particularly dangerous, sometimes taking lives and destroying entire homes in the process.
Is your Vaillant boiler experiencing some of the brand's most common fault codes? We have many covered many Vaillant boiler error codes in the following guides:
Cost of Hiring a Heating Engineer to Fix an F83
On average, heating engineers charge around £30 to £60 an hour in labour fees.
However, this would depend on a range of factors like where in the UK you live.
For instance, labour costs tend to be higher in the Southeast while they are generally lower than the UK average in North England, Scotland, and Northern Ireland.
As you may notice from the list below, we mention ‘replacing an entire boiler’.
This is because if your PCB or heat exchanger need replacing, your boiler may be beyond economic repair, especially if it’s quite old.
However, many Britons may consider it ridiculous to consider buying a new boiler in the current economic climate.
But the good news is that you can purchase a boiler replacement on finance if you’d prefer. In other words, you can buy now and pay later.
Here is the overall cost of potential F83 fixes (labour + supply costs both included):
Fixing a leak - £30 to £120.
Fixing a heat exchanger - £50 to £200.
Recalibrating thermistors - £50 to £200.
PCB to thermistor wiring issue - £50 to £200*
Replacing a heat exchanger - £400 to £600.
Increasing gas flow pressure - £30 to £120.
PCB Replacement - £300 to £600.
Replacing an entire boiler - £800 to £2,800.
*PCB to thermistor wiring would need to be dealt with by a qualified electrician.
Get in touch with us if you have any questions about an F83 fault or a related issue with your Vaillant boiler.
Will my Warranty Cover Repairs or Replacement Work for an F54 Fault?
A Vaillant boiler warranty only covers error/fault that has come about due to a manufacturing-related defect.
In addition, even if you can prove that a manufacturing fault has caused an F83 (where repair/replacement work is necessary), you need to check that your warranty is actually still alive.
The duration of Vaillant boiler warranties can differ. Moreover, specific these warranties also come with specific terms and conditions.
Here are some examples relating to a domestic Vaillant boiler warranty:
Your boiler has been serviced by a Gas Safe Register engineer once a year when needed.
It was fitted and commissioned by a Gas Safe Register engineer, and this took place within six months of despatch.
So, it’s unfortunately unlikely that your Vaillant warranty will cover an F83 error.
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