Galvanic corrosion. The zinc coating on galvanised iron (GI) fittings corrodes over time when exposed to moisture and hydrogen sulphide present in town gas. The zinc flakes, creating pitting and micro-cracks in the metal. The corrosion is invisible from outside until the fitting fails.

Wear from disassembly cycles. Unions are designed to be disconnected and reconnected. But each cycle wears down the metal mating faces that form the gas-tight seal. After 10–20 years of a single installation, the faces are already degraded. Disturbing the union during a heater replacement accelerates the wear past the point of reliable resealing.

Misalignment stress. If the adjoining gas pipes are not perfectly aligned — which they rarely are in residential installations after years of building settlement and pipe movement — lateral stress pulls the union connection apart gradually. The mating faces no longer press evenly, creating gaps that allow gas to escape.

Incorrect sealant usage. This is the most common misconception. The threads on a gas union do not seal the gas. The threads provide mechanical force to press the two metal mating faces together — the seal is at the faces, not the threads. Applying thread seal tape or pipe dope to union threads is ineffective and often creates a false sense of security. The gas escapes through the mating faces, not through the threads.

Copper is a soft metal. This is the source of its biggest problem when reused.

During the first installation, the compression fitting is tightened hard onto the copper pipe. The pipe deforms under this force — it loses its perfectly round cross-section and compresses into the fitting. This deformation is how the joint seals. It is intentional.

During dismantling for the heater replacement, the fitting is loosened and the pipe is pulled free. This is the second round of heavy mechanical work on the same soft copper. The pipe deforms again.

During reinstallation, the same pipe must be compressed back into a fitting for the third time. But a compression fitting requires a perfectly round pipe to create an airtight seal. After three rounds of spanner work, the copper has lost its round profile permanently. No amount of skill can make an out-of-round pipe seal reliably in a compression fitting.

The deformation risk is the primary reason copper gas pipes cannot be reused. This is a physics problem, not a workmanship problem.

The compression fitting threads themselves also degrade from repeated spanner work — the same thread damage seen in brass fittings. Corrosion is possible but less common than with GI pipe.

Main protective bonding (SS638:2018, Section 544.1). This connects the gas and water services to the electrical earth at or near the point of entry to the building. This is the building-level bonding, typically installed during the original electrical fit-out. Section 544.1.2 requires the connection to be made to “any gas, water or other service.”

Supplementary bonding (SS638:2018, Section 544.2). This is local bonding at the point where the metal pipes connect to the gas water heater — on the aircon ledge itself. This is what Homeone installs on every job. It connects the metal gas pipe and the metal water pipe to the earthing system right where the heater is, ensuring that all metal surfaces on the ledge are at the same potential.

If the building’s main bonding is absent or compromised — which is common in older properties — the supplementary bonding at the heater becomes the only path to earth for stray current on those pipes. In that scenario, it is not supplementary. It is the only bonding.

Thread deformation and galling. Tapered pipe threads rely on metal-to-metal wedging to seal. Loosening and retightening strips away the tolerance that created the original seal. The threads flatten, gall, and misalign. The joint no longer seals cleanly.

Micro-fractures in the valve body. The mechanical stress of unseating a seized, aged valve introduces micro-fractures in the forged brass body. These are invisible to the naked eye but will grow under the thermal cycling and vibration of the new heater. Over weeks or months, they can develop into a gas leak.

Brittle handle and seals. The plastic or die-cast aluminium handle and internal packing seals degrade over years of heat and humidity exposure. Reinstalling the valve subjects these fatigued components to fresh torque. The handle becomes prone to snapping during the next emergency isolation attempt — exactly when you need it most.

Every job at Homeone is photographed systematically. The photos document every stage of the work — before, during, and after. This documentation is kept permanently for future reference.

The documentation is reviewed by multiple people: the Compliance Manager reviews every job in detail from the office, the LGSW reviews the documentation and endorses the work, and the operations team monitors for patterns or deviations across all jobs.

This is more oversight than a single licensed professional standing on site could provide. One person on site sees one job in real time, misses what they miss, and leaves no record of what they observed. Homeone’s model puts multiple reviewers on every job, each looking from a different angle, with a permanent photographic record.

Every job at Homeone is photographed systematically. The photos document every stage of the work — before, during, and after. This documentation is kept permanently for future reference.

The documentation is reviewed by multiple people: the Compliance Manager reviews every job in detail from the office, the Licensed Plumber reviews the documentation and endorses the work, and the operations team monitors for patterns or deviations across all jobs.

This is more oversight than a single licensed professional standing on site could provide. One person on site sees one job in real time, misses what they miss, and leaves no record of what they observed. Homeone’s model puts multiple reviewers on every job, each looking from a different angle, with a permanent photographic record.

This is the most important distinction between Homeone’s certificate and what other installers provide.

Homeone does not declare the installation safe and hand you a piece of paper. Homeone invites you to witness the final pressure test with your own eyes. The manometer gauge board is mounted where you can see it. The water level is visible. If it holds steady for 5 minutes, the installation is gas-tight. You see this happen. You are not asked to take anyone’s word for it.

After the pressure test, the technician confirms gas delivery by turning on the cooking hob and the water heater to verify that gas flows normally to all appliances. This concludes the commissioning.

The certificate you sign is your acknowledgement that you witnessed the test and that the installation was tested in your presence. Homeone invites every customer to take a photo of the test result for their own peace of mind.

 Most other gas heater installers use a handheld electronic gas detector. The technician waves the device near each joint and listens for an alarm or watches a reading on the screen. If the detector doesn’t alarm, the joint is considered safe.

The problems with handheld detection

It tests one spot at a time. The technician must physically move the detector to every joint and hold it there. If a joint is missed — behind a pipe, in a tight corner, at the gas meter — the leak is not detected.

It misses small leaks. Handheld detectors have a sensitivity threshold. Micro-leaks from deformed threads, worn mating faces, or hairline cracks may not trigger the alarm. These micro-leaks are real — they release gas continuously — but they are below the detection threshold of the handheld device.

The result is subjective. The technician interprets the reading. A fluctuating number on the screen, a brief alarm in a windy area, a detector that hasn’t been calibrated recently — all of these introduce human judgment into what should be a binary pass/fail result.

The usage may be more performative than diagnostic. Waving a handheld detector near a joint, hearing no alarm, and issuing a certificate creates the appearance of testing without the rigour of an actual pressure test. The paperwork looks the same. The assurance is not.