Waking up to no hot water is never a good start to the day — especially during Melbourne’s cold mornings. Before you panic, there are several common causes you can check yourself, and some that need a professional.

Check These First

1. Is the Power or Gas On?

It sounds obvious, but it’s worth checking:

• Electric systems - Check your switchboard. The hot water circuit breaker may have tripped. Reset it and wait 1-2 hours for the water to heat up
• Gas systems - Check that your gas supply is on. Look at the pilot light if your system has one — it may have gone out
• Solar systems - Check the booster switch. Cloudy days may require the electric or gas booster to be turned on

2. Has Someone Used All the Hot Water?

If you have a storage tank system, the hot water supply is limited. If multiple people have showered or you’ve run the dishwasher and washing machine, the tank may simply be empty.

Recovery times:

• Electric storage: 2-4 hours for a full reheat
• Gas storage: 30-60 minutes for a full reheat
• Continuous flow: Unlimited hot water (if the unit is working)

3. Is the Thermostat Set Correctly?

The thermostat on your hot water system may have been accidentally adjusted. Check that it’s set to 60°C at the unit (this is the Australian standard for preventing bacteria growth).

Common Causes by System Type

Electric Hot Water Systems

• Tripped circuit breaker - Reset at your switchboard
• Faulty heating element - The most common cause of failure; needs replacement
• Failed thermostat - The system doesn’t know when to heat
• Sediment buildup - Reduces efficiency and can cause the element to fail
• Off-peak timer issue - If you’re on off-peak tariff, check the timer is set correctly

Gas Hot Water Systems

• Pilot light is out - Follow the manufacturer’s instructions to relight it
• Faulty thermocouple - The safety device that monitors the pilot light
• Gas supply issue - Check other gas appliances are working
• Blocked flue - Prevents proper ventilation and triggers safety shut-off
• Ignition failure - Electronic ignition systems can fail over time

Continuous Flow (Tankless) Systems

• Error code displayed - Check the display panel for an error code and refer to the manual
• Flow rate too low - These systems need a minimum flow rate to activate
• Gas supply issue - Check other gas appliances
• Scale buildup - Hard water deposits reduce heat exchange efficiency
• Exhaust blockage - Birds’ nests or debris in the external flue

Solar Hot Water Systems

• Booster not working - Check the booster element or gas supply
• Cloudy weather - Extended overcast periods deplete stored heat
• Pump failure - The circulation pump may have stopped (split systems)
• Collector damage - Hail or debris may have damaged roof panels

When It’s Definitely Time to Call a Plumber

Contact a licensed plumber if:

• You’ve checked the basics and still have no hot water
• The water is discoloured or smells unusual
• You see water pooling around the base of the system
• The system is making unusual banging or rumbling noises
• Your energy bills have spiked without increased usage
• The system is over 10 years old and frequently breaking down
• There’s an error code you can’t resolve

How Long Do Hot Water Systems Last?

Knowing your system’s age helps you decide between repair and replacement:

If your system is approaching the end of its lifespan and frequently needing repairs, replacement is usually more cost-effective.

Hankook Plumbing Hot Water Services

We diagnose and repair all types of hot water systems across Melbourne’s eastern suburbs:

• Fast diagnosis - We identify the problem quickly
• Same-day repairs - Most repairs completed on the first visit
• All brands serviced - Rheem, Rinnai, Bosch, Dux, Aquamax, and more
• Replacement options - If repair isn’t worth it, we’ll provide honest advice and competitive quotes

Don’t suffer through cold showers. Call Hankook Plumbing on 0407 756 172 for fast hot water repairs.