Central Heating Leak Detection in South Molton

Symptoms

A property in EX36 had a 9-radiator heating system served by a combination boiler. During initial testing, the system pressure dropped from 2 bar to 0 bar within just 15 to 20 minutes — a rate of loss that pointed clearly to an active leak somewhere within the pipework rather than a minor sealing issue or valve weep.

The presence of a damp spot beneath a kitchen unit added to the concern, though the source of the leak was not immediately obvious. Central heating leak detection was required to establish whether the fault lay beneath the floor, within the walls, or elsewhere in the system before any repair work could be planned.

Given the age of the installation — pipework embedded in screed for over 40 years — a thorough, methodical investigation was essential to avoid unnecessary disruption while still locating the fault precisely.

Methods Used

The investigation began with thermal imaging and a damp meter to identify areas of concern. The damp meter confirmed a damp spot beneath the kitchen unit, and thermal imaging gave a useful picture of the pipe runs beneath the floor, though it did not highlight any clear anomaly at that stage.

The system was then drained, the boiler isolated, and the pipework pressure tested with air at 2 bar. A slow, steady pressure drop was recorded over the 30-minute test window, confirming an active leak in the system.

A compressor was used to clear water from the pipework before tracer gas was introduced at 2 bar. This is the critical stage in central heating leak detection where an inert gas mixture is pushed through the drained system and detected at the surface above any breach.

Strong tracer gas readings were recorded in the entrance hall. Carpet and underlay were lifted in that area — revealing significantly wet underlay — and acoustic leak detection equipment was then used to pinpoint the exact position of the leak beneath the screed before excavation was carried out.

Investigation Process

1. 1
   Initial Assessment

   The 9-radiator system and combination boiler were assessed. A pressure drop from 2 bar to 0 bar within 15 to 20 minutes was recorded during initial testing.

2. 2
   Thermal Imaging and Damp Meter Survey

   Thermal imaging was used to identify pipe runs, and the damp meter detected a damp spot beneath the kitchen unit. No definitive leak location was established at this stage.

3. 3
   System Drained and Boiler Isolated

   The heating system was fully drained and the boiler isolated to allow air pressure testing of the pipework in isolation.

4. 4
   Air Pressure Test

   The system was charged with air at 2 bar. A slow, steady pressure drop was observed and the pressure did not hold for the 30-minute test period, confirming an active leak.

5. 5
   System Purged with Compressor

   A compressor was used to remove as much residual water from the system as possible in preparation for tracer gas introduction.

6. 6
   Tracer Gas Introduced

   Tracer gas was introduced at 2 bar. Strong readings were detected in the entrance hall, redirecting attention from the kitchen to the hallway.

7. 7
   Carpet and Underlay Lifted

   With the customer's permission, furniture was moved and the hallway carpet was lifted. The underlay beneath was found to be significantly wet, consistent with a long-standing subsurface leak.

8. 8
   Acoustic Leak Detection

   Acoustic equipment was used to pinpoint the exact position of the leak beneath the screed in the entrance hall.

9. 9
   Excavation and Repair

   The screed was excavated at the identified location. The leaking section of pipework was cut out and replaced with new materials.

10. 10
    System Refill and Boiler Issue Identified

    During refill, the boiler began heating rapidly, indicating an air-lock. The boiler was left switched off and the customer's son was advised that a Gas Safe registered engineer would be needed to purge the boiler.

Result & Outcome

The leak was located beneath the screed in the entrance hall of the property in EX36. Tracer gas directed the investigation to the correct area, and acoustic detection then identified the precise point, allowing a targeted excavation rather than speculative lifting of a wide floor area. The leaking section of pipework was cut out and replaced with new materials on the same visit.

For any central heating leak detection job involving pipework embedded in screed for decades, pinpoint accuracy matters — unnecessary excavation in a hallway causes significant disruption. The combination of tracer gas and acoustic correlation delivered a precise result, with the wet underlay confirming the leak had been active long enough to saturate the floor build-up.

Two follow-up actions remain. A Gas Safe registered engineer will need to attend to purge the air-lock from within the boiler before it is returned to full service. The excavated area has been temporarily covered with wood by the customer's son, and the screed must be allowed to dry thoroughly before permanent reinstatement. Given the age of the pipework, re-piping the system from the loft using radiator drops is strongly recommended should any further leaks develop.