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At Homecure we’ve been providing installation, repairs and boiler servicing for Vaillant boilers for a number of years, and our Gas Safe engineers deal with Vaillant faults every week.
The most common causes of a Vaillant breakdown are low water pressure, faulty pumps and gas valves, and frozen condensate pipes.
There are some instances where you may be able to resolve the problem without calling an engineer, which we explain in more detail below. However, for those that require part changes, internal boiler checks or anything requiring technical expertise, you should always get in touch with a qualified engineer.
Read through our list of common breakdowns and fixes below to learn more about what to do when Vaillant boilers need troubleshooting and what to do next time you experience a fault.
An F22 error code means the water pressure in the system is low. You can usually fix it by topping up with the filling loop to the pressure given in your boiler manual. Some models, such as the ecoTEC plus, have a built-in filling loop, so follow the manual for yours.
Vaillant ecoTEC boilers are known for displaying the F75 code, which means the boiler has not detected the pressure change it expects when the pump starts. The pump or the pressure sensor may be involved, but the code alone does not identify the failed part, so one of our team needs to visit and test both.
No heating or hot water is a common Vaillant fault, and ignition is often the cause. F28 means the boiler has failed to ignite. A Vaillant F29 error is different: the flame went out while the boiler was running and it failed to relight. Both can be the result of a frozen condensate pipe, a problem with the gas supply or worn spark electrodes. Homecure engineers diagnose and fix these every week.
An F27 code means the boiler is detecting a flame when it shouldn’t be, for example after the burner has shut off. The boiler locks out for safety, and it needs a Gas Safe engineer to investigate. Contact us for boiler repairs.
A frozen condensate pipe can create a number of problems on different Vaillant boilers. If this is the cause you can usually fix this yourself by thawing it out with warm water. However, if you do not feel confident taking this sort of action, the Homecure team are always available to help.
Sometimes you may experience a slow rate of water coming out of taps and shower heads in the home. This problem may be related to the pump, the height position of your water tanks or be linked with an open-vent heating system.
An F62 code can indicate a gas valve or control fault. It needs a Gas Safe engineer to diagnose, which the Homecure team can help with.
If your boiler fires up when you don’t expect it to, the cause is usually the thermostat or the time and temperature settings. Check the programme and the temperature settings so it only comes on when you want it to. The older ecoTEC Plus 831 was known for this, but that model has now been discontinued.
F52 and F53 are different faults. F52 usually points to a problem with a sensor or its connection, while F53 is a mass flow sensor fault; possible causes include a wet or blocked venturi filter or low gas flow pressure. The exact meaning varies by model, so check your manual. Both need a Gas Safe engineer to test and diagnose.
A Vaillant boiler producing the F68 error code means the flame is unstable which could be caused by a number of reasons. This includes the gas flow pressure being too low, a frozen condensate pipe or air being present in gas. One of our qualified team members can resolve this quickly and safely.
Vaillant boiler repairs can be the result of a number of different issues. The table below describes the most common reasons for a breakdown and whether or not you will need to call out a Homecure engineer.
Boiler issue | Possible reason | Should I call a Homecure engineer? |
Banging noises or whistling | This is usually caused by air in the system, or by kettling from limescale or sludge on the heat exchanger. | Yes |
Frozen condensate pipe | This will produce an error code on the boiler warning you of the problem. | Maybe – you can try to defrost the pipe using warm water but if that doesn’t work you should give us a call. |
No heating or hot water | There can be a number of reasons for this, either to do with valves, water levels or thermostat issues. | Yes |
Leaks | Leaks are typically the result of a broken piece of equipment and may not always be externally visible | Yes |
Low pressure | May be caused by a leak, faulty valves or radiators that need to be bled. | Can usually be fixed at home by using the filling loop, but if not, give us a call. |
Problems with thermostat | This may be related to current timings and settings. | Yes – it may need to be replaced if this does not resolve the issue |
Boiler shutting down | May be the result of a faulty thermostat, low water pressure, low water flow or a faulty fan or circulation pump | Yes |
Cold radiators | Radiators not heating up when turned on could be caused by a build-up of air or sludge in the system. | You can bleed the radiators with a key – if this doesn’t fix the issue, or you aren’t comfortable doing it, call our team. |
Kettling noises | Caused by a build-up of limescale or sludge in the heat exchanger, or poor circulation. | Yes |
Our team at Homecure Plumbers offers a range of services across a number of other brands, including boiler repairs for Worcester, Glow Worm and Baxi.
There are a long list of Vaillant error codes and below we explain some of the most common to help you understand what they mean and how they can be fixed.
Error Code | Description |
F22 | Low water or system pressure. Top up with the filling loop to the pressure given in your boiler manual. |
F27 | The boiler is detecting a flame when it shouldn’t be. It needs a Gas Safe engineer to investigate. |
F28 | Failure to ignite: the boiler tried to light but no flame was detected. Causes include a frozen condensate pipe, a gas supply problem or worn ignition electrodes. |
The flame went out while the boiler was running and it failed to relight. Causes include the gas supply, a frozen condensate pipe or worn electrodes. | |
The boiler has not detected the expected pressure change when the pump starts. The pump or pressure sensor may be involved, but the code alone does not identify the failed part, so an engineer needs to test them. | |
F62 | Can indicate a gas valve or control fault. It needs a Gas Safe engineer to diagnose. |
F20 | The boiler has overheated and shut down. Let it cool and do not keep resetting it. It needs checking by a Gas Safe engineer. |
F32 | Issues with the fan or flue tend to be the cause of this error code displaying. The flue can be unblocked by an engineer, or they can replace the fan, if needed. |
F61 | A faulty gas valve is likely to produce this Vaillant error code. This will be different to an incorrectly adjusted valve and can be replaced by an engineer. |
F63 | The F63 error code will be linked to the PCB, which will require an engineer to use a multi-meter to determine the exact cause of the issue. |
F68 | If the flame is either constantly weak or keeps going out it will produce this code. An engineer can diagnose if it is down to a blocked flue, faulty fan or air pressure switch or an incorrectly adjusted gas valve. |
From the job: ecoTEC Plus 832 showing F.75
ecoTEC Plus 832 showing F.75 every time the heating came on. Checked both the pump and the pressure sensor. Pressure was fine but the pump wasn’t starting, so the pump was the fault. Fitted a new one and it ran without a problem.
Expert notes by Jamie Watkins, Gas Safe registered engineer (Gas Safe ID 6115118), Homecure Plumbers – Gas Safe Reg 505421
From the job: ecoTEC Pro 28 locked out on F.28
ecoTEC Pro 28 locked out on F.28. Frozen condensate pipe. Thawed it and got the boiler back on, then swapped the outside section for wider 32mm pipe and lagged it so it’s less likely to freeze again.
Expert notes by Jamie Watkins, Gas Safe registered engineer (Gas Safe ID 6115118), Homecure Plumbers – Gas Safe Reg 505421
See our Vaillant boiler repairs and Vaillant boiler servicing pages. Repairs from £95 + VAT for the first hour, including diagnosis (or a fix if it can be done within the first hour with no parts needed), no callout charge. Prices apply during office hours; parking or the congestion charge may be added.
Press and hold the reset button for a few seconds. If the boiler locks out again, do not keep resetting it. Note the fault code, check it in the table above and book a Gas Safe engineer if it is not one you can fix yourself.
Usually because of a leak somewhere in the system, or water escaping through the pressure relief valve because the expansion vessel has lost its charge. Top it up with the filling loop (see how to repressurise a boiler). If it keeps dropping, book a Vaillant boiler repair.
Typically 10 to 15 years with a yearly service. Vaillant’s warranty is 5 to 10 years, depending on model, when the boiler is fitted by an accredited installer.
Once a year. Vaillant needs a yearly service by a Gas Safe engineer to keep the warranty valid. See our Vaillant boiler servicing.