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Last updated: 10th April, 2024


Pressure Dropping on Boiler Every Day

Pressure Dropping on Boiler Every Day

Key takeaways

  • Boiler pressure consistency is key to an efficient heating system.
  • Regular drops in pressure necessitate investigation for leaks or mechanical faults.
  • Professional assessment may be required to correct pressure issues safely.

Boiler pressure is the measure of balance between water and air within the central heating system. Specifically, it is the force with which water circulates from the boiler to radiators and back.

Pressure Dropping on Boiler Every Day: Comprehensive UK Fixes and Troubleshooting Guide

Experiencing a drop in boiler pressure on a daily basis can be both puzzling and concerning for homeowners.

This phenomenon is indicative of an issue within the central heating system, which demands prompt attention to prevent further complications. The pressure of a boiler is an essential parameter that ensures the smooth operation of a heating system, affecting the efficiency of how well radiators heat and the overall performance of the boiler itself.

Recognising the correct pressure for your boiler is the foundation to diagnosing and addressing pressure loss. Typically, the gauge on your boiler will signal an ideal pressure range.

Should the needle stray below this range, it could lead to insufficient heating or in severe cases, total system shutdown. Consistent drops in pressure can stem from several causes, including leaks within the system or a failing expansion vessel. When such issues emerge, solutions range from simple homeowner fixes to the need for professional intervention by a Gas Safe registered engineer.

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What Is Boiler Pressure?

Boiler pressure is the measure of balance between water and air within the central heating system. Specifically, it is the force with which water circulates from the boiler to radiators and back. A healthy system needs a certain level of pressure to operate correctly.

Optimal Pressure Levels:

  • Normal boiler pressure: Typically between 1-2 bars

  • Green zone: Indicates acceptable range on the gauge

  • Red zone: Warns of too high or too low pressure

Components Influencing Pressure:

  • Pressure gauge: Displays the pressure level within the system

  • Filling loop: Used to manually repressurise the system

  • Valves: Including the pressure relief valve and Schräder valve, contribute to maintaining or adjusting pressure

  • Expansion vessel: Absorbs excess water pressure

Common Issues:

  • Low Boiler Pressure: Often a result of leaks or bleeding radiators

  • Losing Pressure: May indicate a problem with the expansion vessel or relief valve

Maintaining the correct pressure is essential; too low and hot water might fail to reach your taps, too high and there could be a risk of damage. It is crucial for homeowners to check their boiler pressure regularly—a simple glance at the gauge can suffice. Should the needle fall outside the 'green zone', action may be required. This could include repressurising the system with the filling loop or locating potential leaks.

In summary, a boiler's pressure level is a vital sign of its health, and maintaining it within the specified limits ensures both efficiency and longevity of the heating system.

What Should My Boiler Pressure Be?

Maintaining the correct boiler pressure is critical for the efficient operation of your heating system. The ideal pressure levels ensure your boiler functions optimally and preserves its longevity.

Low Boiler Pressure

Optimal Pressure Range: Typically, a well-functioning boiler will operate within the pressure range of 1 to 1.5 bar. This range is often indicated on the boiler pressure gauge as the green zone, providing a visual cue for optimal pressure.

  • Consequences of Low Pressure: If the gauge indicates below 1 bar, the boiler is experiencing low pressure, which can result in inadequate heating performance and potential boiler shutdown.

  • Common Causes: Causes might include system leaks or recently bled radiators.

  • Resolution Steps:

    1. Check for visible leaks and repair if necessary.

    2. Re-pressurise the boiler to the recommended level using the filling loop.

    3. Seek professional help if the problem persists or is unclear.

High Boiler Pressure

Warning Levels: When the pressure exceeds 2.5 bar, the needle on the boiler pressure gauge enters the red zone. This area serves as an alert that the pressure is too high.

  • Risks of High Pressure: Excessive boiler pressure can place undue strain on your heating system, risking damage and leaks.

  • Usual Suspects: Overfilling during re-pressurisation, a faulty expansion vessel, or a malfunctioning pressure relief valve could be to blame.

  • Tackling High Pressure:

    1. Bleed radiators to dispel excess water, relieving pressure.

    2. If this does not remedy the situation, inspect the expansion vessel and pressure relief valve.

    3. Consult a certified engineer if the complication does not resolve.

Pressure Dropping on Boiler Every Day

Persistent low boiler pressure can be worrying for homeowners, as it suggests an underlying issue with the heating system. This section will address signs to watch for, potential causes, and practical fixes that alleviate the common problem of daily pressure drops in boilers.


When a boiler loses pressure consistently:

  • The pressure gauge will frequently register in the red zone, below 1 bar.

  • Heating performance can diminish; radiators may take longer to warm up.

  • The boiler may display fault codes or shut down as a safety precaution.


Several factors contribute to the loss of pressure:

  1. Leaks: The most frequent cause, often originating from pipe joints or the boiler itself.

  2. Faulty Pressure Relief Valve: Discharges water to maintain pressure but may be releasing too much.

  3. Expansion Vessel Issues: A malfunctioning Schrader valve or diaphragm can lead to pressure changes.

  4. Filling Loop Left Open: After repressurising, it must be fully closed to prevent pressure escape.


Resolution to pressure loss entails:

  1. Leak Detection and Repair: Inspect the system; apply sealant or tighten connections.

  2. Valve Checks: Replace the pressure relief valve if faulty.

  3. Expansion Vessel Recharge: If the diaphragm has failed, it might require recharging or replacing.

  4. Bleeding Radiators: To remove air pockets that cause pressure disparities.

  5. Repressurising: Use the filling loop to return the boiler to the correct pressure (1-1.5 bar).

By staying vigilant to deteriorations in boiler performance and addressing the root causes, homeowners can mitigate the implications of a boiler losing pressure each day.

When to Call a Gas Safe Engineer

Experiencing a daily drop in your boiler's pressure is not only frustrating but could signify a deeper issue. In certain situations, it becomes essential to seek the expertise of a qualified Gas Safe engineer.

Persistent Drops in Pressure: If repressurising the system doesn't yield a lasting fix and the pressure continues to fall, this could indicate problems such as a leak in the system, malfunction of the pressure relief valve, issues with the filling loop, or expansion vessel complications.

Visible Signs of a Leak: Should there be damp patches on walls or floors, or if you spot any water around the boiler, professional help is required. A Gas Safe engineer can perform meticulous leak detection to identify the origin of the water leak.

System Inefficiency: When the boiler fails to operate efficiently, manifesting through inadequate heating or hot water, a qualified engineer should inspect the unit. The engineer might identify it's essential to recalibrate the system or, in some cases, suggest the installation of a new boiler.

  • Safety Precautions: Never attempt DIY fixes on gas boilers if you are not competent. Addressing problems related to gas appliances without proper training and expertise is dangerous and illegal.

  • Certification Verification: Always verify the credentials of your engineer. The law stipulates that only Gas Safe registered engineers are authorised to repair gas boilers.

In conclusion, while minor pressure fluctuations are often manageable, recurring issues warrant professional help. A certified engineer will ensure repairs are done safely and effectively, restoring your peace of mind and the functionality of your heating system.

Do I Need a New Boiler?

Deciding on whether a new boiler is necessary can often be a complex judgement. Should your boiler be experiencing a regular pressure drop, it may not be as straightforward as needing a complete replacement. Many issues can be remedied by a qualified engineer, which is considerably less expensive than purchasing a new unit.

First, consider the age of your boiler. If your appliance is a modern boiler, manufactured within the last decade, and serviced regularly, a replacement might not be needed. Modern combi and system boilers can often be repaired, with parts being more readily available. It’s essential to consult with a local installer or engineer to diagnose the issue accurately.

In contrast, if your device is a conventional boiler and has been serving diligently for many years, parts may be less accessible or your boiler might be less energy-efficient. This could justify an upgrade to a more economical model which can save money on energy bills in the long run.

Here's a quick checklist to decide on repairs or replacement:

  • Boiler age: Less than 10 years might favor repair, particularly for modern boilers.

  • Repair frequency: Continuous repairs suggest a replacement may be cost-effective.

  • Energy efficiency: Older models may lead to high energy bills; consider a modern combi or system boiler.

  • Breakdown severity: Minor issues can be fixed, but significant problems often demand a new boiler.

When the choice is still unclear, it’s imperative to consult with a qualified engineer, who can offer expert advice tailored to your specific circumstances. Remember, a reliable diagnosis and a professional installation are pivotal to the longevity and efficiency of any boiler.

iHeat New Boiler Costs

Boilers can be a daunting purchase for many people as they’re an appliance with a lot of responsibility, providing heat for you and your family is something you want to get right. Boilers aren’t exactly a quickly disposable item either, potentially lasting you a decade.

Effectively, new boiler cost can be split into two segments: the first is the actual boiler itself (unit price), and the second is the cost of the boiler being installed (set up) in your property by an expert engineer. 

Here at iHeat, we want to remove all of this undue stress and make the decision making process of upgrading to a new central heating system, as easy as possible.

Boiler costs can vary depending on a number of factors including their brand, model, fuel, output, warranty, labour and installation type. Typically a new boiler will cost between £1,845 and £3,500, below is a list of average boiler installations offered by iHeat (guide only).

Installation Type

Price (inc VAT)

Combi to combi swap


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System to combi conversion


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New boiler install


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Back boiler to a combi


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System to system


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Frequently Asked Questions

Why does my boiler keep losing pressure every day?

A boiler may lose pressure daily due to leaks in the system, including radiators and pipework, or issues such as a faulty pressure relief valve or a malfunctioning expansion vessel. These problems may cause continuous pressure drops, demanding attention.

Can a boiler just lose pressure without a leak?

Yes, boilers can lose pressure without a visible leak. This situation can be due to a faulty expansion vessel or a hidden leak that isn't easily noticeable. Additionally, air within the system from recent radiator bleeding can also cause pressure loss.

Why do I have to keep adding pressure to my boiler?

Continuous pressure loss necessitating regular repressurisation suggests a persistent fault in the system such as leaks or component failure, including the pressure relief valve or expansion vessel. It's essential to identify and repair the root cause.

Is it safe to leave a boiler with low pressure?

Operating a boiler with consistently low pressure can lead to inefficient functioning and potential damage to the boiler. Whilst not immediately dangerous, it's advisable to address the issue promptly to avoid further complications.

What do I do if my boiler pressure keeps dropping?

If the boiler pressure keeps dropping, check for visible leaks, bleed the radiators to remove any air trapped in the system, and inspect the pressure relief valve and expansion vessel for faults. If the problem persists, contact a Gas Safe registered engineer.

Should boiler pressure drop to zero when not in use?

Boiler pressure should not drop to zero when not in use. Some drop in pressure is normal, but a drastic fall could indicate a leak or fault within the system. Professional advice may be necessary if pressure falls significantly during non-operation periods.

Stephen Day profile photo
Article by
Stephen Day | Co-founder
Gas Safe registered and FGAS certified engineer with over 20 years experience in the heating and cooling industry.