Hot Water Leak Detection in Burnham

Symptoms

A property in SL1 was experiencing persistent damp throughout the hallway, with wet floors in both the hallway and the downstairs WC. Access had already been made into the walls to expose the supply pipework and soil stack before the engineer arrived, indicating the issue had been present long enough to warrant preliminary investigation.

The heating and hot water system comprised a system boiler serving a radiator circuit, alongside an unvented hot water storage cylinder. Critically, there was no recorded instance of the boiler losing pressure, which helped narrow the source of the leak away from the heating circuit.

The spread of dampness and wet flooring pointed to a concealed leak within the buried pipework — a scenario that required structured hot water leak detection to isolate the affected section and identify the precise fault location before any repair could be carried out.

Methods Used

The investigation began with systematic pressure testing across three separate circuits — the external mains supply, the internal mains supply, and the hot water supply — each tested at 3 bar for 30 minutes. This immediately isolated the fault to the hot supply.

A valve was then installed to isolate the branch of hot pipework running beneath the hallway floor, and a repeat pressure test confirmed the leak was located within that specific branch.

With the leak isolated to the hallway floor, thermal imaging was attempted to trace the buried pipework, but the pipes were too deep for a useful thermal signature. Tracer gas was then introduced into the hot supply, and a large gas trace was detected at the base of the soil stack.

This directed the excavation, which was carried out across several areas of the floor until the leaking pipe was found at the kitchen doorway. Hot water leak detection at this level of complexity — involving multiple test methods in sequence — is necessary precisely because buried pipework in a finished floor cannot be located by visual inspection alone.

Investigation Process

1. 1
   Initial assessment

   The engineer assessed wet floors throughout the hallway and downstairs WC, with damp present across the hallway. Wall access to supply pipework and the soil stack had already been made prior to attendance.

2. 2
   System identification

   The hot water and heating system was confirmed as a system boiler with a radiator circuit and an unvented hot water storage cylinder. No pressure loss from the boiler had been recorded, indicating the heating circuit was not the source.

3. 3
   Pressure testing — circuit isolation

   The external mains supply, internal mains supply, and hot water supply pipework were each pressure tested at 3 bar for 30 minutes. The test confirmed a leak on the hot supply.

4. 4
   Valve installation and repeat pressure test

   A 15mm quarter-turn valve was installed on the hot supply to isolate the branch of pipework running through the hallway floor. A further pressure test confirmed the leak was within that branch.

5. 5
   Thermal imaging attempted

   Thermal imaging was used in an attempt to trace the hot pipework beneath the hallway floor, but the pipework was buried too deep to produce a detectable thermal signature.

6. 6
   Tracer gas detection

   Tracer gas was introduced into the isolated hot supply pipework. A large gas trace was detected at the base of the soil stack, indicating the leak position within that area of floor.

7. 7
   Floor excavation and leak found

   The floor was excavated in several targeted areas to locate the pipework. The leak was found in the floor at the kitchen doorway.

8. 8
   Repair carried out

   The leaking section of pipe was cut out and replaced using a 15mm slip coupling, coupling, and 0.5m of 15mm tube.

9. 9
   Post-repair pressure test

   The repaired hot supply pipework was pressure tested at 3 bar for 30 minutes with no loss of pressure, confirming the repair was successful.

10. 10
    Reinstatement

    The pipework was flushed and all excavated areas were back-filled.

Result & Outcome

The leak was located in the hot supply pipework at the kitchen doorway, buried beneath the hallway floor. It was found through a combination of pressure testing to isolate the circuit, tracer gas to direct the excavation, and targeted floor excavation to expose the pipe.

Once located, the leaking section was cut out and replaced. A post-repair pressure test at 3 bar for 30 minutes with no loss of pressure confirmed the repair was complete. The pipework was flushed and the excavated areas back-filled before the engineer left site.

For a job of this type, hot water leak detection requires working through multiple methods in sequence — pressure testing, thermal imaging, tracer gas — because no single technique is sufficient when the pipework is buried deep beneath a finished floor. The result here was a precise location, a clean repair, and a confirmed pressure-tight system.