Before you book
What you need to know.
- A leak from a connection or valve is different from a confirmed leak in the storage cylinder.
- Check the pattern: every outlet, only 1 tap, after heavy use or throughout the day.
- Storage and continuous flow systems need different fault checks, even when both deliver cold water.
- Compare a diagnosed repair with the complete installed replacement, including the condition of the remaining unit.
On this page
The symptom narrows the investigation.
Start with where and when the problem occurs. If every hot outlet is affected, the investigation needs to consider the heater and common supply. If the kitchen is hot but the shower isn't, a local mixer, valve or branch can be involved. That distinction can prevent a working heater being blamed for a fault elsewhere.
Also separate a sudden change from a system that has never met demand. Hot water that used to last through the family's showers but now runs cold deserves a fault assessment. A new pattern after extra occupants, changed shower fittings or building work brings different questions.
Scroll sideways to read every column.
| What you're noticing | What needs checking | What it means for the decision |
|---|---|---|
| Cold water at every hot tap | Heating, controls, energy supply and common valves | An assessment is needed before calling the whole unit failed. |
| Only 1 outlet is lukewarm | The tap or mixer, local connection and temperature control | The fault may be outside the heater. |
| Storage hot water runs out sooner | Heating and recovery, demand and any water loss | Repair and capacity are separate questions. |
| Continuous flow turns hot then cold | Operating water flow, controls and supply conditions | Record when it happens and any fault code. |
| Water beneath the unit | Connections, discharge pipe and the unit itself | Locate the source before judging tank condition. |
| Water is unexpectedly too hot | Temperature control and delivery conditions | Stop using the affected outlet and arrange assessment. |
A cylinder leak and a component leak are different faults.
Water can run down a casing from a connection above it. A discharge pipe can also release water near the base. Neither observation alone proves the storage cylinder has failed. The assessment needs to trace where the water originates and whether it is continuous or linked to heating.
A replaceable fitting or valve may be repaired while retaining a sound unit. A confirmed leak through a deteriorated storage cylinder usually moves the decision towards replacement because changing an external valve won't repair the vessel. Existing product cover can affect the next step, so keep purchase and model details available.
Some relief discharge during a storage heating cycle can be normal. Persistent or excessive discharge needs assessment of the valve, pressure and operating conditions. Don't plug or cap a discharge pipe to stop the water; it serves a safety function.
Storage and continuous flow need different checks.
Electric storage assessment can involve the heating element, thermostat, safety controls and the electricity supply arrangement. Those electrical checks belong to an appropriately qualified person. If heating is restricted to certain times, the available reheating period also matters when investigating a shortage.
Gas storage introduces the gas supply, burner and control system into the assessment. A pilot or ignition problem doesn't establish which part has failed. Leave combustion and gas components to the qualified trade rather than repeatedly trying to restore operation from a general online instruction.
Continuous flow uses a different operating sequence. Water flow, ignition, sensors, controls and supply conditions can influence operation. A displayed code helps narrow the investigation, but its meaning is model-specific and doesn't prove which part must be replaced. Record the code instead of repeatedly clearing it.
Temperature and flow problems aren't always heater failure.
Lukewarm delivery can involve temperature-control plumbing even when water is being heated. A fault at a mixer or a common tempering arrangement needs different work from a failed heating component. Comparing affected outlets and measuring the actual conditions helps identify the right repair area.
Low hot-water flow is also different from water that flows normally but stays cold. Tell the plumber whether the problem developed suddenly, affects every outlet or changes when another tap is used. Recent tapware replacement is useful history, especially when a continuous flow system starts cycling during low demand.
Discoloured water needs its pattern checked too. Note whether it appears on hot only or on cold as well. Colour alone doesn't prove a tank has failed. The assessment needs to consider the supply, pipework and unit rather than replacing equipment based on appearance alone.
What a useful repair assessment should establish.
The visit should connect the observed symptom with an identified fault and explain the proposed work in plain language. Relevant testing depends on system type and trade scope. The useful result is a reason for replacing a component, repairing a connection or investigating the supply further.
After a repair, the relevant operation needs checking. That can include leakage, delivery conditions and how the unit responds to demand. A storage unit may need time to reheat before its full available supply can be judged, so the handover should explain what to expect.
Review the fault history
Record the model, symptoms, affected outlets, recent changes and earlier repairs.
Assess the system and installation
Distinguish the unit fault from supply, valves, outlet plumbing and demand.
Explain the repair options
Identify the proposed parts or work and whether another trade or manufacturer process is needed.
Check and hand over
Explain the result, reheating expectations and any follow-up or remaining limitation.
When repair makes sense and when replacement does.
Repair can be sensible when the fault is isolated, the rest of the unit is in serviceable condition and compatible parts remain available. A component repair can preserve a system that already meets household demand. The decision needs the condition of the whole installation, not only its age.
Replacement deserves consideration where the core unit has failed, deterioration is extensive, parts aren't available or a major repair would leave other substantial problems unresolved. A history of repeated unrelated faults also belongs in the comparison.
Ask for the repair scope alongside the fully installed replacement option where both are practical. Include extra connection work, removal and access. There isn't a universal age or repair-price percentage that decides every system; condition, remaining risk and household needs change the answer.
Scroll sideways to read every column.
| Factor | Supports considering repair | Supports considering replacement |
|---|---|---|
| Fault | An isolated serviceable component or connection | A failed core unit or extensive deterioration |
| Remaining condition | No major additional problems identified | Several significant issues remain |
| Parts | Suitable parts are available | Required parts are unavailable |
| Household fit | The system still meets normal demand | Capacity or arrangement no longer suits |
| Total scope | A defined repair restores the intended operation | A substantial repair leaves a poor overall result |
What affects the repair quote.
The diagnosis, parts, access and work required determine the price. A visible connection repair has a different scope from a control fault requiring specialist testing or parts. Ask about the attendance charge, whether diagnostic work is included and how further work will be authorised.
A return visit can be needed for parts or additional trade work. Confirm who arranges that work and whether it is included. If the unit might have product cover, provide its model, serial number and purchase details before major repairs so the appropriate process can be checked.
For a cupboard, roof space or shared plant area, access can also influence the job. Describe the location honestly; nobody needs to climb or remove covers to collect model details. A photo of the accessible label and surrounding area is enough for the initial discussion.
Prepare the household and handle urgent faults safely.
Keep the area around an accessible unit clear and arrange keys or building-manager access if needed. Note the normal demand and when the fault appears. Let the plumber know if the property has no usable hot water or if a leak is damaging the building.
Don't open electrical covers, adjust gas parts or keep resetting an unexplained fault. Avoid using an outlet that becomes unexpectedly scalding. Keep clear of leaks near electrical equipment. If you smell gas inside, leave the building and call 000 from a safe place.
Scott & Sons offers 24/7 emergency plumbing. Call 02 9482 9199 for an urgent problem and explain the actual hazard, not just that the water is cold. For planned assessment, the enquiry form can include the model, symptoms and access details.