If your gas boiler keeps losing pressure, it can be a concerning issue that indicates a problem within the system. Understanding the common causes and taking the right steps to diagnose and fix the problem can help you restore your boiler’s performance and prevent further damage. This comprehensive guide will provide you with the technical details and expert insights to tackle this issue effectively.
Common Causes of a Gas Boiler Losing Pressure
1. Water Leaks
One of the primary reasons for a gas boiler losing pressure is water leaks in the pipework. These leaks can occur at joints, fittings, and other connections, allowing water to escape the system. Over time, these leaks can lead to mold, rot, and more extensive damage to the surrounding areas.
To identify water leaks, closely inspect the pipework, radiators, and areas around the boiler for any visible signs of moisture or water accumulation. Pay special attention to the connections and joints, as these are common points of failure. You can also use a dye test or a pressure test to pinpoint the exact location of the leak.
2. Faulty Expansion Valve
The expansion valve is a critical component in the gas boiler system, responsible for regulating the pressure by allowing excess water to escape. If this valve is malfunctioning, it can lead to a loss of pressure in the system.
Inspect the expansion valve for any signs of damage, such as cracks, corrosion, or blockages. If the valve appears to be faulty, it may need to be replaced by a qualified Gas Safe engineer.
3. Air in the System
Air can enter the gas boiler system through various means, such as when radiators are bled or during maintenance. This trapped air can cause pressure loss and disrupt the proper functioning of the system.
To address this issue, regularly bleed the radiators to remove any accumulated air. This can be done by opening the bleed valves on each radiator until water starts to flow out, indicating that the air has been released.
4. Faulty Pressure Sensor
The pressure sensor is responsible for monitoring and regulating the pressure within the gas boiler system. If this sensor is malfunctioning, it can cause the boiler to lose pressure and potentially shut down.
Check the boiler’s display for any error codes that may indicate a problem with the pressure sensor. If the sensor is faulty, it may need to be replaced by a qualified engineer.
5. Expansion Vessel Issues
The expansion vessel is a crucial component that helps to absorb excess pressure in the gas boiler system. If this vessel is not functioning correctly, it can lead to pressure loss.
Inspect the expansion vessel for any signs of damage or wear, such as cracks, leaks, or a lack of air pressure. If the vessel appears to be faulty, it may need to be recharged or replaced by a qualified engineer.
Steps to Fix a Gas Boiler Losing Pressure
1. Re-Pressurise the Boiler
The first step in addressing a gas boiler losing pressure is to re-pressurise the system. Locate the filling loop and pressure gauge on your boiler, and ensure that the handles are at a 90° angle to the pipe flow. Turn off the boiler, open the filling loop handles, and allow water to flow in until the pressure reaches the recommended level, typically between 1.0 and 1.5 bar.
Once the desired pressure is reached, close the filling loop handles and turn the boiler back on. Monitor the pressure to ensure it remains stable.
2. Bleed Radiators
Bleeding the radiators can help remove any air that has accumulated in the system, which can contribute to pressure loss. To bleed the radiators, follow these steps:
- Ensure the boiler is turned off and the system is cool.
- Locate the bleed valve on each radiator, usually at the top.
- Place a cloth or container under the bleed valve to catch any water.
- Use a radiator key to slowly open the bleed valve, allowing air to escape.
- Close the bleed valve when you see water start to drip out.
- Repeat this process for all radiators in the system.
3. Check for Leaks
Carefully inspect the pipework and radiators for any signs of water leaks or damage. You can use methods like taping a plastic bag to the pressure release valve to detect any small leaks that may not be visible.
If you identify any leaks, it’s essential to address them promptly to prevent further pressure loss and potential water damage.
4. Consult a Professional
If the problem persists after attempting to re-pressurise and bleed the system, it’s recommended to consult a qualified Gas Safe engineer. They can perform a more thorough diagnosis, identify any underlying issues, and provide the necessary repairs or replacements to restore the proper functioning of your gas boiler.
Technical Specifications and DIY Considerations
Pressure Levels
The recommended pressure for a gas boiler is typically between 1.0 and 1.5 bars when the boiler is turned off and cool. When the boiler is turned on, the pressure should increase slightly to 1.0-2.0 bars.
Annual Maintenance
Regular annual boiler services can help prevent unexpected problems and catch minor issues before they become more serious. During these services, a qualified engineer can inspect the boiler, check for any leaks or pressure issues, and perform necessary maintenance to ensure optimal performance.
DIY Precautions
While some steps, such as re-pressurising and bleeding radiators, can be performed by homeowners, it’s essential to ensure that any work on the boiler is done by a qualified Gas Safe engineer. Attempting to repair or service the boiler without the proper expertise can lead to further damage or safety risks.
References:
– Viessmann UK. (n.d.). What should I do if my boiler loses pressure? Retrieved from https://www.viessmann.co.uk/en/heating-advice/boilers/boiler-loses-pressure-what-to-do.html
– Proper DIY. (2023, December 1). Why Your Boiler is Losing Pressure and How to Fix It. Retrieved from https://www.youtube.com/watch?v=KBaDQsWrPBs
– Reddit. (2021, January 4). Combi Boiler constantly losing pressure, thoughts? Retrieved from https://www.reddit.com/r/DIYUK/comments/kq6cgm/combi_boiler_constantly_losing_pressure_thoughts/
– Checkatrade. (n.d.). What To Do If Your Boiler Loses Pressure. Retrieved from https://www.checkatrade.com/blog/expert-advice/what-to-do-boiler-loses-pressure/
– BOXT. (n.d.). Why Does My Boiler Pressure Keep Dropping? Retrieved from https://www.boxt.co.uk/boilers/guides/why-does-my-boiler-pressure-keep-dropping