Should I repair or replace my failed hot water system?

If the system is more than 10 years old, most plumbers recommend replacement rather than repair — the cost of parts and labour for a major repair often exceeds 50% of a new system, and the remaining life of the old unit is limited. Newer systems are also significantly more energy efficient.

How long does hot water system replacement take?

Replacing a like-for-like electric or gas storage system typically takes 2–4 hours for a plumber. Switching system types (e.g., to heat pump) may require additional electrical or plumbing work. Same-day service is usually available for emergencies in metropolitan Melbourne.

Homeowner symptom guide · Melbourne

Hot Water System Not Working: Diagnosing the Problem

A failed hot water system in a Melbourne home can mean anything from a tripped circuit breaker to a burst tank requiring same-day replacement. The right first step depends on your system type — gas, electric storage, instantaneous gas, or heat pump. This guide helps you diagnose the most common causes before calling a plumber.

Common Causes

• Electric storage system — tripped circuit breaker or failed element: check the switchboard for a tripped breaker on the hot water circuit. If it resets and trips again, the element has likely failed and needs replacement.
• Gas system — pilot light out or gas supply issue: on older gas storage systems, the pilot light can extinguish. Modern systems with electronic ignition may show an error code. Check that your gas supply is active (try other gas appliances).
• Instantaneous gas system — error code: gas instant systems display fault codes for ignition failures, insufficient gas flow, or overheating. The code identifies the fault — most can be cleared by a licensed gas fitter.
• Heat pump — fault code or freezing: heat pumps can trip in very cold Melbourne weather if the heat exchanger ices up, or can show fault codes for refrigerant or compressor issues.
• Temperature relief (T&P) valve discharge: if hot water is running from the overflow pipe on the outside of the house, the pressure relief valve is discharging — a sign of excessive system pressure or temperature that needs urgent assessment.

When to Be Concerned

⚠ Hot water is flowing from the overflow/relief valve pipe continuously
⚠ The hot water system is more than 10 years old and fails to produce any hot water
⚠ Rust or discolouration in the hot water supply
⚠ Unusual smells (sulphur/rotten egg) from hot taps
⚠ Visible corrosion, water pooling, or active leaks at the unit

What to Do

1 Check the switchboard for a tripped circuit breaker (electric systems) and the gas supply for other gas appliances (gas systems) before calling a plumber.
2 Look up the error code on your system's make and model — many are fixable without a service call.
3 If the overflow valve is discharging, turn the cold water supply to the system off and call a licensed plumber immediately — do not attempt to close the relief valve yourself.
4 If the unit is more than 10 years old and has failed comprehensively, discuss replacement options as the same-day priority with your plumber.

Frequently Asked Questions

Should I repair or replace my failed hot water system?

If the system is more than 10 years old, most plumbers recommend replacement rather than repair — the cost of parts and labour for a major repair often exceeds 50% of a new system, and the remaining life of the old unit is limited. Newer systems are also significantly more energy efficient.
How long does hot water system replacement take?

Replacing a like-for-like electric or gas storage system typically takes 2–4 hours for a plumber. Switching system types (e.g., to heat pump) may require additional electrical or plumbing work. Same-day service is usually available for emergencies in metropolitan Melbourne.

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