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  • Boiler Losing Pressure : Causes, Fixes, and What You Need to Know

Updated: October 14, 2024

Boilers play a crucial role in maintaining the comfort of our homes by providing heat and hot water. But when your boiler loses pressure, it disrupts that comfort and can indicate underlying issues. In this guide, we’ll dive into the reasons why boilers lose pressure, how to fix them, and when it’s time to call in a professional or consider replacing your boiler.

What is Boiler Pressure?

Boiler pressure refers to the balance of water and air inside your boiler’s sealed system. The right pressure is essential for the boiler to function efficiently, delivering hot water to your taps and heat to your radiators.

If the pressure is too low, your boiler may struggle to circulate water, resulting in inefficient heating. On the flip side, too much pressure can damage components, making the system inefficient.

Does Your Boiler Pressure Keep Dropping?

Boilers losing pressure is quite common and often nothing to worry about if it happens occasionally. This can be a result of natural water loss over time. However, frequent or rapid drops in pressure could signal a more severe issue. Let’s explore the possible causes.

Common Causes of Boiler Pressure Loss

  1. Leaks in the System
    A leak anywhere in your heating system can cause pressure loss. The tricky part is that these leaks might not be immediately visible, as they could be hidden within walls or under floors. How to Spot a Leak:
  • Inspect visible pipes for damp spots or water marks.
  • Focus on pipe joints and bends, where seals are prone to weakening.
  • Check radiators for any signs of leakage around valves or connection points. Fixing a Leak:
    If you suspect a leak, contact a Gas Safe engineer. Resealing or repiping might be necessary, depending on the extent of the damage.
  1. Internal Boiler Leaks
    Sometimes the leak is within the boiler itself, often due to wear and tear over time. Internal leaks can be trickier to detect without removing the cover. How to Identify:
  • Look for water pooling beneath your boiler.
  • Check for rust or corrosion on internal components (this is best left to a professional). Fixing Internal Leaks:
    You’ll need a qualified engineer to diagnose and replace the faulty parts. In some cases, the heat exchanger may be the issue, and replacing it can be expensive.
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  1. Faulty Boiler Components
    Over time, boiler components can fail due to wear and tear. If your boiler is displaying error codes or shutting down frequently, this could indicate a problem with internal parts. Signs of Faulty Parts:
  • Boiler displays error codes related to pressure loss.
  • Unusual noises such as banging, whistling, or gurgling. How to Fix:
    A professional engineer will need to replace the broken components. Costs can vary depending on the part, and if your boiler is older, sourcing replacements might be challenging.

How to Check and Repressurise Your Boiler

If the pressure has dropped below the recommended level, you can top it up yourself. Here’s a step-by-step guide:

  1. Locate the Filling Loop:
    Underneath your boiler, you’ll find a flexible silver pipe, often with black taps. This is the filling loop used to increase pressure.
  2. Open the Taps:
    Turn the taps slowly until the pressure gauge rises. The optimal pressure is around 1 bar when the boiler is off.
  3. Close the Taps:
    Once the pressure is in the green zone (usually marked on the gauge), close the taps completely.

If you’re repressurising frequently, there might be a deeper issue with the system.

How long does it take to fit a new boiler?

Is Low Boiler Pressure Dangerous?

Low boiler pressure itself is not typically dangerous, but it can indicate a system issue that needs addressing. Low pressure means water can’t circulate effectively, causing the boiler to shut off as a safety measure.

If left unresolved, persistent low pressure can lead to larger issues like internal damage or increased energy bills due to inefficiency.

When Should You Call a Professional?

While topping up your boiler pressure is simple, repeated pressure drops suggest it’s time to call in a Gas Safe engineer. They can check for leaks, faulty components, and other underlying problems.

Boiler Keeps Losing Pressure Even After Repressurising?

If your boiler is consistently losing pressure even after you repressurise it, this suggests a more significant issue:

  • Persistent Leaks: Hidden leaks, especially in inaccessible areas like under floors or inside walls, can cause continuous pressure drops.
  • Faulty Expansion Vessel: The expansion vessel inside the boiler helps regulate pressure. If it’s faulty, pressure might rise too high or fall too low quickly.
  • Pressure Relief Valve Issue: If the pressure relief valve is malfunctioning, it could be releasing water and causing the system to lose pressure.

Should You Repair or Replace Your Boiler?

When faced with boiler issues, you’ll often need to decide between repair or replacement. Here are some considerations:

  1. Age of the Boiler: If your boiler is over 10 years old, repairs may become more frequent and costly. Older boilers are also less efficient, potentially leading to higher energy bills.
  2. Repair Costs: Weigh the cost of repair versus replacement. A significant repair on an old boiler might not be worth it compared to investing in a new, more efficient model.
  3. Efficiency: New boilers come with better energy ratings, meaning they’ll save you more on bills in the long run.

Common Boiler Brands and Their Error Codes

Understanding boiler error codes can give you insight into what’s wrong. Here are some common brands and their pressure-related error codes:

  1. Worcester Bosch: E2, A1, CE 207, H07, 224 V, 1017W, 2970 B
  • Models: CDi Classic, Greenstar 25i, Greenstar 30i
  1. Vaillant: F.24, F.12, F.22, F.73, F.75
  • Models: EcoTEC, EcoPure, Turbomax Plus
  1. Baxi: E28, E119, 118, H.02 – 06, E.02 – 7
  • Models: Baxi 600 combi, Baxi 200, Baxi DuoTec
  1. Ideal Boilers: F1 or ‘Water Pressure’ description on display.
  • Models: Logic, Isar, Vogue Max

Final Considerations: Key Takeaways

  1. Top Up First: Always check if topping up the pressure solves the problem before looking into repairs.
  2. Call a Professional for Persistent Issues: Don’t ignore continuous pressure drops—seek professional help to avoid larger problems.
  3. Evaluate the Need for Replacement: If your boiler is old and repairs are getting expensive, a replacement might be more cost-effective.
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Conclusion

Boiler pressure problems can range from minor to severe, but addressing them quickly is key to maintaining an efficient heating system. Regularly check your boiler’s pressure gauge, top it up when necessary, and don’t hesitate to call in a professional if issues persist. If your boiler is aging, it might be time to consider an upgrade to avoid costly repairs in the future.

Read about: Common Sime Boiler Error Codes

Also read about: Types of Boilers Explained: Combi, System, and Heat-Only