Vaillant ecoTEC F22 fault code

Vaillant ecoTEC F22 fault code explained

The F22 fault code is probably one of the most common faults on the Vaillant ecoTEC range of boilers. If you have a Vaillant ecoTEC boiler you will probably see the F22 fault code at some point.

This fault code will cause your Vaillant boiler to stop working, leaving you without central heating or hot water.

The F22 fault code essentially means that the printed circuit board(PCB) on the boiler doesn’t think there is enough pressure in the boiler for it to continue working safely.

If you look in the Vaillant ecoTEC installation manual under the F22 fault code it states the following;

“Safety switch-off: Low water pressure No/insufficient water in the product or the water pressure is too low”

“Check: Plug, cable to heating pump or water pressure sensor, water pressure sensor, heating pump.”

The F22 fault code is a failsafe which ensures that the boiler will not work if there is not enough pressure in the boiler for it to safely operate without overheating the appliance.

The printed circuit board on a Vaillant ecoTEC boiler knows if there is enough pressure in the boiler as there is a pressure sensor fitted to the boiler.

The pressure sensors job is to measure the pressure inside the boiler. It communicates with the printed circuit board via a variable low voltage, and if the printed circuit board doesn’t think there is enough pressure the boiler will stop working and display an F22 fault code.

Unlike a lot of fault codes the F22 fault code is telling exactly you what the problem is – there isn’t enough pressure in the boiler.

It’s not uncommon to have to add pressure to your boiler or central heating system from time to time, and it doesn’t necessarily indicate that you have a problem.

There are quite a few different possible causes for your boiler to lose pressure and display the F22 fault code. Possible causes include some of the following possibilities;

Issues with the expansion vessel, failed pressure relief valve, failed primary heat exchanger or a leak on the central heating system somewhere.

If your boiler has an issue with the expansion vessel, the pressure will shoot up above 3 bar whenever you put the heating on.

The pressure relief valve which opens at 3 bar, will dump the excess pressure outside and you will generally have to keep adding pressure to your boiler even time you use the heating.

If your boiler has an issue with the pressure relief valve, your boiler will slowly lose pressure over time.

If the primary heat exchanger has failed your boiler will also slowly lose pressure over time.

If you have a leak on your central heating system somewhere this may prevent itself as an obvious leak.

This is why it is important to get a suitable Gas Safe registered heating engineer with experience on Vaillant ecoTEC boilers, otherwise you could waste money fitting parts that are unnecessary.

When to call a gas engineer to fix your boiler

If your Vaillant ecoTEC boiler is constantly losing pressure and displaying the F22 fault code, it is important to take action as soon as possible. While some issues can be resolved by homeowners themselves, others require the expertise of a qualified Gas Safe registered heating engineer.

Because the F22 fault code can be caused by several different faulty parts, it is extremely important to get a suitable heating engineer with experience on Vaillant ecoTEC boilers, otherwise you could end up wasting money fitting parts to your boiler that are unnecessary.

So it usually best to get a qualified heating engineer to have a look at your boiler at your earliest convenience.

How to prevent the F22 fault code

A lot of the time certain faults on a Vaillant ecoTEC boiler can be prevented with regular annual servicing and maintenance. This is often true of the F22 fault code as well.

One of the most important components on a Vaillant ecoTEC combination or system boiler is the expansion vessel.

Water expands when heated, and the expansion vessels job is to take up that extra expansion in the system whenever you use the central heating.

The expansion vessel is a serviceable component and one of the most common causes for a boiler to start losing pressure displaying an F22 fault code.

The expansion vessel is often overlooked by engineers on a routine boiler service.

What an engineer can do to help prevent the F22 fault code is to service the boilers expansion vessel while servicing the boiler.

Vaillant ecoTEC boilers affected by the F22 fault code

The F22 fault code on Vaillant ecoTEC boilers can affect any combination, system or heat-only boiler.

So this fault code can affect any Vaillant ecoTEC Pro combination boilers, any ecoTEC plus 800 Series combination boilers and any ecoTEC plus 600 series system boilers.

Below is a list of ecoTEC boilers that can be affected by the F22 fault code;

• ecoTEC Pro 24 and ecoTEC Pro 28 natural gas combination boilers
• ecoTEC Plus 800 Series 824, 828, 831, 837 and 937 natural gas combination boilers
• ecoTEC Plus 800 Series 825, 832, 835, 838 and 938 natural gas combination boilers
• ecoTEC Plus 600 Series 612, 615, 618, 624, 630 and 637 natural gas system boilers

Frequently asked questions:

Is my boiler showing an F22 fault code worth repairing ?

Yes definitely, most of the time your broken Vaillant ecoTEC boiler displaying an F22 fault code will be worth repairing.

Obviously the cost to repair your boiler will be determined by which parts need to be replaced.

Most of the time the F22 fault code is caused by an issue with the expansion vessel and/or pressure relief valve which can easily be serviced or replaced.

However unfortunately in some cases the primary heat exchanger has failed and is responsible for the constant loss of pressure.

On first generation Vaillant ecoTEC boilers manufactured between 2005 – 2011, which used a Giannoni primary heat exchanger, heat exchanger failure was not so common.

However on second generation Vaillant ecoTEC boilers manufactured from 2011 onwards, they use a Sermeta heat exchanger and in our experience these heat exchangers are much more prone to failure.

You would need a competent, Gas Safe registered heating engineer to have a look at your boiler and make an assessment to determine exactly which parts might need to be replaced.

Before replacing your boiler it is always worth getting a suitable Gas Safe registered heating engineer, with experience working on Vaillant ecoTEC boilers, to make an assessment of your boiler so you can determine whether it is worth fixing not.

Can I repair the F22 fault code myself?

Yes you can solve an F22 fault code yourself, by adding some pressure to your boiler, we recommend pressurising your boiler to somewhere between 1 – 1.5 bar.

If your boiler is constantly losing pressure, then aside from check your central heating system fort leaks. Aside from that repairing the F22 fault code will usually require removing the cover of your boiler to replace parts which you are not legally allowed to do unless you are a Gas Safe registered heating engineer.

Is the F22 fault code dangerous?

No definitely not , the F22 fault code is not inherently dangerous, it’s the opposite. Modern Vaillant boilers are designed with fail safes in place to make sure that the boiler will only work if it safe to do so.

As such if your boiler is constantly coming up with an F22 fault code after you’ve added pressure, the best thing to do it get it repaired at your earliest convenience, by a suitable Gas Safe registered heating engineer – ideally one that has experience working on Vaillant boilers.