The Vaillant EcoTec series is one of the most popular boiler ranges in the UK. These boilers are known for their energy efficiency, quiet performance, and long life. But like any heating system, they can develop problems over time. When something goes wrong, it can be stressful—especially during winter. As Vaillant Boiler Service Experts London, we repair and service EcoTec boilers every day. In this guide, we explain the most common issues and the best ways to solve them.
Low pressure is one of the most common problems with the Vaillant EcoTec range. You may notice that your heating is weak or your hot water is not as warm as before. The pressure gauge on the boiler may show a reading below 1 bar.
You can top up the pressure using the filling loop. Set the pressure to around 1.2 bar. If the pressure keeps dropping, you need a Gas Safe engineer to inspect the boiler. The leak might be hidden in the system or the expansion vessel may need replacement.
F28 and F29 are ignition errors. The boiler tries to start but fails. This often means there is a gas supply problem or an issue with the ignition system.
Check your gas supply and make sure the gas valve is open. You can also check if the condensate pipe is frozen. If none of these are the issue, call a Gas Safe engineer. Ignition problems need expert diagnosis to avoid further damage.
The F75 error is very common in Vaillant EcoTec boilers. The message appears when the boiler does not detect the correct pressure rise at startup.
The best fix depends on the condition. Sometimes cleaning the pump helps. In older boilers, replacing the pump or pressure sensor is the right solution. Power flushing may also be needed if sludge is blocking the system.
Many homeowners report that their Vaillant EcoTec boiler heats the radiators but does not produce hot water.
A stuck diverter valve is the most common cause. An engineer can repair or replace it. If the heat exchanger is blocked with limescale, cleaning or replacing the part will restore hot water. In areas like London where water is hard, this issue is very common.
If the boiler turns off shortly after starting, it could be due to an overheating problem.
An engineer will check the pump, clean the system, and inspect the sensors. In many cases, poor circulation is the root cause. Once fixed, the boiler will run smoothly again.
Gurgling, whistling, or banging noises are signs that something is wrong.
Bleeding radiators may help if air is trapped. But if limescale is the problem, an engineer may need to clean or replace the heat exchanger. Installing a scale reducer can prevent the issue in the future.
The F22 error points to a lack of water. This is a safety feature to stop the boiler from running dry.
Top up the boiler pressure. If the error keeps coming back, you may have a leak or a failing pump. A Gas Safe engineer can find the cause and fix it safely.
EcoTec boilers are condensing boilers, so they create a small amount of waste water. This water flows outside through a condensate pipe. In winter, the pipe can freeze.
Pour warm (not boiling) water over the pipe to melt the ice. For long-term protection, consider insulating the pipe or increasing its diameter.
This happens when the water becomes hot, then cold, then hot again.
A heating engineer can test the sensors and clean the heat exchanger. Sometimes fitting a new part is the best option for long-term reliability.
Many issues with Vaillant EcoTec boilers need expert care. Trying to repair gas components without training is dangerous. You should call a Gas Safe engineer if:
At Vaillant Boiler Service Experts London, we provide fast, safe, and professional repairs for all Vaillant EcoTec models. With years of experience, our engineers can handle any fault—big or small.
You can avoid most problems with regular boiler maintenance.
Regular servicing keeps your boiler efficient, safe, and less likely to break down.
The Vaillant EcoTec series is reliable and efficient, but like all boilers, it needs proper care. Most issues—like low pressure, ignition faults, F75 errors, and blocked pipes—can be repaired quickly by a skilled engineer. If you notice symptoms such as strange noises, error codes, or loss of hot water, do not ignore them. Early action prevents bigger problems later.
For fast and reliable help, Vaillant Boiler Service Experts London is here to keep your EcoTec boiler running at its best.
