Hot Water System Not Working? Here’s What to Do

Waking up to no hot water is one of the most disruptive household plumbing failures — and one of the most common plumbing callouts in Melbourne. Before you call a plumber, there are a few things worth checking yourself. Here’s a step-by-step guide to diagnosing a hot water system that’s not working.

Step 1: Check Whether It’s a Gas or Electric System

The type of hot water system you have determines where to start:

• Electric systems — check the circuit breaker at your switchboard. A tripped breaker is one of the most common causes of sudden hot water loss.
• Gas systems — check whether the pilot light is lit (on older systems) or whether the ignition is working (on newer systems). Also check that the gas supply to the property hasn’t been interrupted.

Step 2: Check the Pressure Relief Valve

Most hot water systems have a pressure relief (TPR) valve with a small pipe running to a drain. If this valve has opened and released water, it could indicate that the system has overheated or the valve itself is faulty. Don’t attempt to repair a TPR valve yourself — call a licensed plumber.

Step 3: Check Your Hot Water Timer or Tariff

Some electric hot water systems are connected to an off-peak electricity tariff and only heat during specific times (typically overnight). If your system hasn’t heated during its scheduled window, you may just need to wait — or check with your energy provider that the off-peak tariff is still active.

Common Causes of Hot Water System Failures

1. Faulty thermostat

The thermostat controls the water temperature. When it fails, the system may stop heating entirely or heat water to an unsafe temperature. Thermostat replacement is a common repair that usually takes under an hour.

2. Failed heating element (electric systems)

Electric hot water systems use one or two heating elements. When an element fails, you’ll get partial or no hot water. Replacement is typically straightforward for a plumber.

3. Pilot light out (gas systems)

On older gas systems, the pilot light can go out due to wind, gas supply interruption, or a faulty thermocouple. Many systems have relighting instructions on the unit itself — follow these carefully, or call a plumber.

4. Sediment build-up

In areas with hard water, sediment can build up in the bottom of a storage tank, reducing efficiency and eventually causing the system to fail. Flushing the tank regularly (annually) extends system life.

5. The system has reached end of life

Electric hot water systems typically last 8–12 years; gas systems 10–15 years. If your system is older than this and failing, replacement is usually more cost-effective than repair.

When to Call a Plumber Immediately

• You can see water leaking from the tank or the pressure relief valve
• You smell gas near the hot water unit
• The unit is making unusual noises (banging, hissing, popping)
• The water is discoloured (rusty or brown) when hot
• You’ve tried the basic checks and still have no hot water

Hot Water Repairs and Replacements in Melbourne

Sedcon Plumbing responds to hot water callouts across Melbourne same day wherever possible. We carry common replacement units so we can restore hot water on the first visit in most cases.

Learn more about our hot water repair and replacement service.

Call or text us on 0468 013 012 — we’ll get it sorted.

Learn more about our Hot Water Repairs Melbourne service, or see all suburbs we cover across greater Melbourne.