How to Fix a Boiler Losing Pressure

Overview

A boiler losing pressure is a common issue that can affect your heating. This guide covers diagnosing and fixing the problem.

Step-by-Step Fix

1. Begin by carefully locating the pressure gauge, which is typically found on the front display panel of your boiler. This gauge often looks like a small dial or a digital display, and it shows the current pressure reading of your heating system.
2. Check the pressure reading on the gauge when your boiler is cold and not actively heating. For most domestic boilers in the UK, the ideal pressure should fall within the green zone, typically between 1 and 1.5 bar.
3. If the pressure gauge is showing a reading below 1 bar, you'll need to repressurise the system using the filling loop. Carefully look for the filling loop, which is usually a short, flexible silver hose connecting two pipework valves underneath your boiler.
4. Gently open both of the valves on the filling loop, one at a time, allowing mains water to enter the system. Keep a close eye on the pressure gauge as it slowly rises, aiming for a reading of approximately 1.5 bar.
5. Once the gauge indicates 1.5 bar, firmly close both filling loop valves in the order you opened them to stop the water flow. It's crucial to then detach the filling loop hose (if detachable) and inspect the connection points for any drips or leaks immediately.
6. If your boiler loses pressure again quickly after repressurising, particularly within a few days or weeks, this indicates a potential leak somewhere in your central heating system. At this point, it's best to contact a Gas Safe registered engineer for a thorough inspection and diagnosis.

Common Error Codes

Review the common error codes and operating symptoms below to quickly identify the root cause of the fault before ordering replacement parts.

Frequently Asked Questions