Central Heating Leak Detection in Maidenhead

Symptoms

At a property in SL6, the heating system had developed a hidden leak that was causing pressure loss across the circuit. The system comprised a conventional boiler and radiator circuit, an unvented indirect hot water storage cylinder, and an underfloor heating circuit — a configuration that makes tracing the source of a leak considerably more involved than a standard setup.

Compounding the situation, the boiler itself was defective and could not be fired at the time of the visit, possibly due to a blocked heat exchanger. This meant the system could not be run normally during initial checks, and the leak had to be located through detection methods alone rather than by observing active pressure behaviour.

Central heating leak detection in circumstances like these — where the boiler is non-functional and the pipework runs beneath a tiled concrete floor — requires a methodical approach. There were no visible signs of water damage or obvious wet patches to guide the investigation, so tracer gas techniques were needed to pinpoint the source.

Methods Used

All accessible pipework was visually inspected first, but no obvious signs of a leak were found.

Tracer gas was introduced into the heating pipework at the boiler with the system drained down. A strong gas trace was detected at the left-hand side of the shower room radiator. The tiled concrete floor was excavated at that location, exposing the pipework below.

Investigation Process

1. 1
   Visual inspection of pipework

   All accessible pipework throughout the property was visually checked. No obvious signs of a leak were found at this stage.

2. 2
   System drained and tracer gas introduced

   The heating circuit was drained down and tracer gas was introduced at the boiler. A large gas trace was detected at the left-hand side of the shower room radiator.

3. 3
   Floor excavated and leak located

   The tiled concrete floor was excavated at the indicated location. A leak was found on a soldered tee in the buried copper pipework.

4. 4
   Leaking section cut out and replaced

   The defective soldered tee and the surrounding section of copper tube were cut out. A new 22mm x 15mm tee, a 15mm coupling, and 0.5m of copper tube were installed as a replacement.

5. 5
   Pressure test carried out

   The repaired system was pressure tested at 2 bar for 60 minutes. No pressure loss was recorded, confirming the repair was sound.

6. 6
   System filled, vented and treated

   The heating circuit was refilled and vented. Sentinel X400 was added to the system to attempt to clear the suspected blockage in the pipework, with the customer advised it must be drained out per the manufacturer's instructions.

7. 7
   Boiler referral advised

   As the boiler remained defective and could not be fired during the visit, the customer was advised to have it checked by a heating engineer.

Result & Outcome

The leak was traced to a soldered tee in the copper pipework buried beneath the tiled concrete floor on the left-hand side of the shower room radiator. The faulty section was cut out and replaced with new copper tube and fittings. A subsequent pressure test at 2 bar held for 60 minutes with no drop in pressure, confirming the repair was complete and the circuit was sound.

For any central heating leak detection job where the pipework runs beneath hard floor finishes, pinpointing the exact location before excavating is critical. Tracer gas testing meant the excavation was targeted directly at the leak, avoiding unnecessary damage to the surrounding floor area.

Sentinel X400 was added to the system to address the suspected blockage in the pipework — likely related to the boiler's defective heat exchanger — and the customer has been advised to drain and flush the system in line with the manufacturer's guidance. The boiler itself still requires attention from a heating engineer before the full system can be returned to normal operation.