Why Does My Boiler Keep Losing Pressure October 31, 2025 If you have noticed your boiler pressure dropping regularly, you are not alone. This is a common issue for homeowners and it can lead to heating problems, boiler lockouts, and ongoing frustration if it is not addressed properly. Understanding what causes boiler pressure loss can help you spot early warning signs and know when it is time to call a professional. Common reasons a boiler keeps losing pressure Boiler pressure issues usually point to a fault somewhere within the heating system rather than the boiler simply being old or worn out. Pressure should remain fairly stable, so any regular drop suggests something needs attention. Boiler leaks within the heating system One of the most common causes of low boiler pressure is a leak somewhere in the system. This could be from pipework under floors, radiators, valves, or internal boiler components. Even small leaks can cause gradual pressure loss over time, often without obvious signs like water pooling. Leaks should always be inspected by qualified professionals, as even small issues can affect system safety and long term reliability. Faulty pressure relief valve releasing water The pressure relief valve is designed to protect your boiler if pressure becomes too high. When this valve develops a fault, it may release water even when pressure levels are normal. This causes the system pressure to drop repeatedly and often results in water visible outside through the discharge pipe. If the valve continues to release water, it usually needs replacing rather than adjusting. Expansion vessel issues causing pressure fluctuation The expansion vessel absorbs pressure changes as water heats and cools. When it loses air or fails internally, pressure can rise during heating and drop again once the system cools. This cycle leads to frequent pressure loss and repeated topping up. Expansion vessel problems are common and should be handled by experienced heating engineers in Wilmslow, Altrincham and Stockport who can safely repressurise or replace the component. Recently bled radiators lowering system pressure Bleeding radiators releases trapped air but it also releases some water from the system. After bleeding radiators, boiler pressure often needs topping up using the filling loop. If pressure continues to fall after this, there may be another underlying issue. Always monitor the pressure gauge after maintenance to ensure it stabilises. Problems with the boiler filling loop The filling loop is used to top up boiler pressure, but worn valves or loose connections can allow water to escape slowly. This can cause pressure to drop even when the boiler appears to be working normally. A faulty filling loop should be repaired promptly to prevent long term pressure problems. Internal boiler component faults In some cases, internal components such as heat exchangers or seals may be failing. These faults are harder to detect without professional inspection and often require specialist boiler repairs to prevent further damage. When losing pressure becomes a safety concern If your boiler regularly drops below the recommended pressure range, it may shut down to protect itself. Ignoring repeated pressure loss can lead to more serious faults, higher repair costs, and reduced heating efficiency. Ongoing pressure issues should always be checked by qualified engineers rather than repeatedly topping up the system. Need help with boiler pressure problems in Wilmslow, Altrincham and Stockport? If your boiler keeps losing pressure and topping it up is becoming a regular task, it is time to get professional advice. 7 Day Plumbing Services Ltd provides reliable boiler repairs and experienced heating engineers across Wilmslow, Altrincham and Stockport. Our team can diagnose pressure faults, repair leaks, and restore your heating system safely and efficiently. Contact us today to book a visit or use our online contact form to arrange professional support.
