Central Heating Leak Detection in Northallerton

Symptoms

A property in HG4 was experiencing a loss of pressure on the central heating system, prompting a central heating leak detection visit to identify the source. The heating had been running for two hours before the engineer arrived, meaning the system was fully up to temperature and ready for a thorough assessment.

Methods Used

The central heating leak detection process began with thermal imaging to trace the pipe routes beneath the floors, followed by damp meter readings across the ground floor. No heat anomalies or wet floors were detected, though elevated moisture readings above the skirting boards were noted — consistent with what is commonly seen in older terraced properties and not indicative of an active leak at those points.

With the system pressurised to 2.5 bar and the heating switched off, an acoustic survey was conducted across all accessible pipework, which returned leak noise on every pipe tested. The strongest signal centred on the external drain cock, where water was also visible beneath it.

Thermal imaging of that water showed a temperature of 30°C, indicating the source was nearby. The downstairs circuit was isolated and drained, tracer gas was introduced at 2 bar, and it was rapidly detected both at the external drain cock and internally beneath the corner unit, confirming the leak location.

Investigation Process

1. 1
   System at temperature on arrival

   The boiler had been running for two hours before the engineer arrived, so the heating system was fully up to temperature and ready for thermal assessment.

2. 2
   Thermal imaging of pipe routes

   Thermography was used to trace all pipe routes beneath the floors. The routes showed clearly, but no heat patches or anomalies were present at floor level.

3. 3
   Damp meter survey

   Protimeter readings were taken throughout the ground floor. All floors measured dry; some elevated moisture was recorded above skirting boards, consistent with the age of the terraced property.

4. 4
   System pressurised and acoustic survey performed

   The heating was turned off and pressure was raised to 2.5 bar. An acoustic survey of all accessible pipework returned leak noise on every pipe tested.

5. 5
   Strongest signal at external drain cock

   The clearest acoustic signal was at the external drain cock. Water was visible beneath it, and thermal imaging measured that water at 30°C, indicating the leak source was close by.

6. 6
   Downstairs circuit isolated and drained

   Isolation valves in the floor were closed and the downstairs half of the system was drained down to allow tracer gas introduction.

7. 7
   Tracer gas detected at two points

   Tracer gas introduced at 2 bar was quickly detected at the external drain cock and internally beneath the corner unit, confirming the leak position before excavation.

8. 8
   External brickwork excavated

   At the customer's request, the area outside by the drain cock was excavated by removing bricks. The leak was immediately visible as water spraying from pinholes in the buried pipe.

9. 9
   Damaged section replaced and repair tested

   The affected section of 15mm copper pipe was cut out and replaced with new barrier pipe and couplers, and a new brass drain cock was fitted. The repair held at 3 bar for 45 minutes with no further pressure drop.

10. 10
    System refilled and returned to service

    The heating system was refilled, bled, and switched back on, restoring normal operation.

Result & Outcome

The leak was located at the external drain cock, where pinholes in a buried section of 15mm copper pipe were causing an active spray leak. This was confirmed by tracer gas detection at the surface before any excavation, with acoustic evidence providing strong directional guidance throughout the central heating leak detection process. Once the brickwork was removed, the damage was immediately visible and unambiguous.

The damaged pipe section was replaced with new barrier pipe, and a new brass drain cock was installed to replace the corroded original. The repair was pressure-tested at 3 bar for 45 minutes with no drop recorded, confirming the system was sound. The system was then refilled, bled, and returned to normal operation.

The engineer noted that an inhibitor should be added to the heating system as soon as practicable. Pinhole corrosion of this type is typically associated with water quality issues within the circuit, and treating the system will help protect the remaining pipework from similar deterioration going forward.