BOILER LOSING PRESSURE?
CAUSES, FIXES & HIDDEN LEAK DETECTION

Here are the most common causes of pressure loss in modern central heating systems:

1. Hidden Leak in the Heating System

Even micro leaks behind walls or under floors can cause gradual pressure loss. These are often invisible but reduce system volume over time.

2. Faulty Expansion Vessel

When the expansion vessel membrane fails, the system cannot maintain stable pressure, especially after heating up.

3. Pressure Relief Valve (PRV) Discharge

If the PRV is stuck or faulty, water can be discharged outside via the overflow pipe – often without the homeowner noticing.

4. Recently Bled Radiators

After bleeding air from radiators, the system needs topping up. Forgetting to do so can result in low pressure and eventual boiler shutdown.

5. Faulty Filling Loop or Loose Connections

A leaking or partially open filling loop can result in pressure instability, or intermittent drops without obvious signs of leakage.

If your boiler is losing pressure, you may notice:

• Constant pressure drop on the gauge (e.g., from 1.5 to 0.5 bar).
• Cold radiators despite the boiler being "on".
• Need to manually top up water every few days.
• Gurgling or tapping sounds in pipes or radiators.
• Error codes such as F22 (Vaillant), F1 (Ideal), or E1 (Baxi).

If your boiler loses pressure again after refilling, you may have a hidden leak in:

• Pipework beneath floors or concrete
• Joints behind walls
• Radiators or towel rails
• Boiler seals or internal fittings

At ADI Leak Detection, we use non-invasive leak tracing technology:

• Acoustic sensors
• Thermal imaging
• Hydrogen tracer gas

These allow us to find hidden water leaks without causing damage to your home.