Top up Vaillant boiler pressure

How to top up Vaillant boiler pressure: a simple DIY guide

If you're seeing an F22 fault code on your Vaillant Ecotec boiler, don't worry — this is typically a simple fix you can handle yourself. As Coventry's trusted heating experts since 2007, we're here to guide you through the process of topping up your boiler's pressure, and to explain when to call our team.

What causes low pressure

The F22 fault code indicates low system pressure, which can occur due to:

Air in the system (common after servicing)
Recent radiator or pipework modifications
Radiator bleeding
Normal pressure loss over time

Occasional pressure top-ups are normal. Frequent drops in pressure, however, might indicate an underlying issue and should be investigated by an engineer.

Identify your Vaillant Ecotec model

Before starting, identify whether you have:

Ecotec Pro: features an external filling loop on the pipes leading to the boiler.
Ecotec Plus: has a built-in filling loop underneath the boiler, with a flap covering the controls.

Consult your boiler manual if you're unsure. If you cannot identify the filling loop, stop and contact an engineer to avoid accidental damage.

Step-by-step pressure adjustment

Locate the pressure display
Find the inverted cone display on digital models, or look for the mechanical gauge near the on/off switch on older models. Aim for the pressure level between the two dotted lines.
Using the filling loop
Open both taps gradually and watch the pressure gauge. Stop when the indicator reaches the middle of the recommended range.
Completing the process
Close both valves to their original positions. The F22 fault should disappear automatically. If needed, press the reset button (marked with a flame and cross symbol).

When to call a professional

While occasional pressure top-ups are normal, frequent adjustments might indicate an underlying issue. If you find yourself repeatedly adding pressure between services, it's time to call our expert team for a thorough inspection. You can book a boiler service with our engineers or explore our service plans for ongoing cover.

Need additional help?

Our experienced engineers are just a phone call away at 024 7667 7667. With over 25 years of industry experience and coverage across Coventry, Nuneaton, Rugby, and surrounding areas, we're here to ensure your heating system runs efficiently and reliably. You can also get in touch to arrange a visit.

Remember, proper maintenance is key to preventing issues. Book your annual service with JLN Plumbing & Heating Limited to keep your boiler running at its best.