If you've noticed that your combi boiler is repeatedly losing pressure, it can be both puzzling and frustrating. A boiler should maintain steady pressure for efficient operation, but when the pressure drops, it can affect everything from your hot water to your central heating. In this blog post, we will delve deep into the common reasons behind pressure loss in combi boilers, ways to identify the issue, how you can resolve some of these issues yourself, and when it might be time to call in a professional.
Understanding Your Combi Boiler’s Pressure System
A combi boiler’s pressure is crucial because it directly influences how effectively it heats water and radiates heat throughout your home. This pressure is maintained by a closed water loop system that includes the boiler and the radiators. Generally, the ideal pressure level is between 1 and 1.5 bar when the system is cold. Anything below this range can indicate a problem.
Common Causes for Pressure Loss
1. Leaks in the Heating System
One of the primary reasons a boiler loses pressure is due to water leaks in the system. These leaks can be tiny and hard to spot, and they might be anywhere in the pipelines, at radiator valves, or even inside the boiler itself.
2. Faulty Pressure Relief Valve
The pressure relief valve is designed to manage the pressure within your boiler's system. If it’s faulty, it might release water unnecessarily, leading to a drop in pressure.
3. Problems With the Expansion Vessel
Combi boilers have an expansion vessel which accommodates the extra volume of water produced when your heating system is heated up. If the vessel fails or if the diaphragm within the vessel is damaged, it can lead to pressure issues.
How to Diagnose Pressure Loss in Your Combi Boiler
Inspecting for leaks is your first step. Check around all visible pipes, the boiler, and radiators for any signs of water leakage. Pay attention to wet spots on the floor, damp patches on walls near the piping, or rust on the radiator valves. Also, observe the pressure gauge on your boiler frequently to see if the pressure drops sharply after topping up.
DIY Fixes for Minor Issues
1. Repressurising Your Boiler
If your boiler pressure is too low, repressurising it is a straightforward process. Locate the filling loop underneath or near your boiler, usually a silver or grey flexible hose with a valve at each end. Open both valves carefully to allow cold water into the system. Watch the pressure gauge and close the valves once it reaches about 1.2 to 1.5 bar.
2. Checking and Replacing the Pressure Relief Valve
If you suspect the pressure relief valve is the culprit, check if it’s expelling water. If it is, you might need to replace this valve. This is something you could attempt if you're competent with home DIY, but if in doubt, always call a professional.
When to Call a Professional
3. Persistent Leaks
If leaks are ongoing or the source of the leak is not visible, a plumbing professional should be called. Hidden leaks can lead to significant damage if not addressed promptly.
4. Expansion Vessel Issues
Problems with the expansion vessel generally require professional diagnosis and repair. The internal diaphragm is not accessible without proper tools and the replacement process is complex.
Long-term Prevention
To prevent future problems, regular servicing of your boiler is indispensable. Annual checks by a qualified boiler technician can help catch issues before they cause a pressure drop. Additionally, keep an eye on the boiler pressure through the gauge and familiarise yourself with your heating system’s manual reset procedures.
Conclusion
A combi boiler losing pressure is a common issue, often due to leaks or component failures like faulty valves or damaged expansion vessels. For minor problems such as repressurising the system, a DIY approach can be safe and effective. However, for persistent losses or when you're in doubt about the cause, contacting a trained professional is the safest option. Regular maintenance remains your best defence against frequent boiler pressure problems, ensuring the longevity and efficiency of your heating system.
