Navigating Vaillant Boiler Issues: Understanding Error Codes

If you keep up with your annual services and monitor your pressure gauge, your Vaillant boiler should give you many years of uninterrupted service. However, if it does experience a fault, don’t panic! A glance at your control panel display screen will show you an error code, beginning with ‘F’, that will help you get to the root of the problem.

Below we’ll discuss some of the Vaillant boiler error codes you are most likely to see on your boiler: 

F.00 And F.01: Interruption To Heating Flow Temperature Sensor, Or ‘NTC Thermistor’ Fault

These error codes indicate a problem with your heating flow temperature sensor (a.k.a. the NTC thermistor). Symptoms include your boiler not getting up to temperature or shutting down unexpectedly. An engineer will need to check the wiring and connections to the temperature sensor, and also check the sensor for damage. The NTC thermistor will need replacing if it’s faulty.

F.20 And F.22: Overheating Due To Low Water, Or ‘Dry Fire’

Dry fire is a heating engineers’ term for when the boiler operates without sufficient water in the system. This is a potentially dangerous situation that could cause the boiler to overheat and damage its components. Leaks and low water pressure are the most common causes of overheating. Check your pressure gauge regularly to keep it within operating pressure. It’s normal for pressure to drop slightly over time, but if you’re topping it up too often, you may have a leak somewhere in the system. Dry fire can also be caused by a faulty pump or blocked valve, which will require an engineer to fix.

F.24: Low Water Or Pump Failure/Blockage

This code indicates low water level, either from insufficient pressure or a faulty pump. The boiler hasn’t overheated, yet, but may not work correctly, and could overheat if the issue is not addressed. Again, check the water pressure and repressurise if necessary. If this doesn’t work, get an engineer to inspect the pump for signs of failure.

F.29: Flame Extinguished

If your boiler fails to ignite or keeps shutting off, you may receive this error code. The usual suspects are an issue with your fan, gas supply, ignition leads, or gas flue. Don’t touch anything to do with your gas supply unless you’re qualified. We recommend calling an engineer to verify that your gas supply is consistent and your gas valves are operating correctly, and to inspect the flue and fan for obstructions.

What Next?

Modern boilers are generally reliable systems, and in our experience, most issues that homeowners face come down to low water pressure. Service can be restored by topping up your boiler using the water inlet valve. However, if your boiler has an electrical or component fault, it’s important to get in touch with an engineer as soon as possible.

Having the error code information to hand – more info can be found on the Valiant website or in your user manual – will help ensure they come to your home with the right part and can get your boiler started again quickly.

If you’re having issues with your Vaillant boiler,  trust the professionals at Nicholson Heating and get in touch with one of our experienced heating engineers today by calling 01670 331404.

Image Source: Vaillant