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Seeing F22 on your Vaillant boiler? No need to stress. This common fault code means your water pressure is low, and while it needs attention, you can often fix it yourself. Let’s walk through what it means and how to get your heating back up and running. Quick action now can save you from bigger headaches (and bills) later.
Your boiler’s water pressure needs to be at the right level. It acts as the “fuel” that keeps hot water flowing through pipes and radiators, ensuring an efficient heating system. When pressure drops too low, your boiler flashes the F22 code and shuts down to protect itself.
The water in your system isn’t just sitting there – it’s working hard to carry heat from your boiler to every radiator in your home. Without enough pressure, that heat can’t travel properly, leaving you with cold spots or no heating at all.
Why does this happen? A few things could be going on:
- Leaks in your pipes or radiators
- Air bubbles trapped in the system
- A pressure sensor playing up
- Natural pressure loss over time
- Recent radiator bleeding without repressurizing
Before you fix anything, let’s figure out why your pressure dropped.
- Sneaky Leaks: Even tiny leaks can add up. Walk around your house checking pipes, radiator valves, and connections for wet patches or water marks. Don’t forget to look under radiators and behind furniture.
- Sensor Problems: Sometimes the sensor itself fails and sends false alarms. Look for error patterns – does it happen after using lots of hot water or at specific times?
- Trapped Air: Feel cold spots on your radiators? Especially at the top? That’s probably trapped air messing with your water flow. Run your hand over each radiator – they should be warm all over.
- System Age: Older systems tend to lose pressure more often. If your boiler’s getting on in years, you might need to top up the pressure more frequently.
Quick tip: Check your pressure gauge – if it’s below 1.0 bar, you’ve found your culprit. The gauge should be easy to read through the boiler’s viewing window.
Let’s get your boiler working again. Here’s your step-by-step guide, and we’ll take it nice and slow:
Step 1: Check Your Pressure
- Find the pressure gauge on the front panel
- Normal pressure sits between 1.0 and 1.5 bars
- Below 1.0? Time to add water
- At 0.5 or lower? Don’t wait – fix it now
- Write down the current pressure – it helps track changes
Step 2: Repressurize the Boiler
- Turn off your boiler first – safety first!
- Find the filling loop (it’s usually a silver hose under your boiler)
- Make sure both ends of the filling loop are properly connected
- Open the valves slowly – quarter turns are enough
- Listen for water flowing into the system
- Watch that pressure gauge like a hawk
- Stop at 1.0-1.5 bars – don’t overdo it
- Close those valves tight – both of them
- Double-check they’re fully closed
- Turn your boiler back on and check if the F22 fault code has cleared. If not, proceed to next step.
Step 3: Bleed Radiators (If Needed)
- Find the bleed valve on each radiator (it’s the small square bit on the side)
- Start with the downstairs radiators first
- Open each valve slowly with your radiator key
- Listen for the hiss of escaping air
- Keep a cloth handy – water will follow
- Close the valve when water appears
- Move to the next radiator
- Check your boiler pressure again – bleeding often lowers it
- Top up pressure if needed
Important: If you’re not confident at any point, stop and call a Heating and Gas Engineers. It’s better to be safe than sorry.
Sometimes DIY isn’t enough. Call a Gas Safe engineer if:
- The F22 code keeps coming back within days
- Your pressure won’t stay steady for more than a week
- You hear strange noises like banging or gurgling
- You spot leaks you can’t fix
- The pressure drops dramatically overnight
- Your boiler makes unusual noises after re pressurising
- You’ve tried the steps above twice with no success
Remember: Trying to fix complex issues yourself might void your warranty and could be dangerous. Gas appliances need proper care from qualified professionals.
Prevention beats cure every time. Here’s how to avoid future F22 headaches:
- Check your pressure monthly – mark it in your calendar
- Book an annual service – it’s cheaper than emergency repairs
- Fix small leaks fast – before they become big problems
- Bleed your radiators every few months
- Keep an eye on your pressure gauge
- Listen for unusual sounds
- Get to know your system’s normal behaviour
- Keep your service history up to date
F22 isn’t the end for your boiler. Often, you can fix it yourself by:
- Checking the pressure carefully
- Adding water slowly and safely
- Bleeding out trapped air
- Knowing when to call for help
- Keeping up with regular maintenance
Most importantly? Trust your gut. If something feels wrong or you’re not confident about fixing it yourself, call a professional. Book our expert Gas Safe heating engineers today for fast, reliable boiler repairs. Better safe than sorry when it comes to gas appliances.
Remember: A warm home needs a happy boiler. Give it regular attention, and it’ll keep you cosy all year round. Just a few minutes of maintenance each month can save you hours of hassle and hundreds in repair bills.