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When your hot water stops working or starts behaving strangely it can be difficult to know whether you are dealing with something minor, a supply issue, or a problem that needs a licensed professional. This guide is designed to help you identify the symptom you are experiencing, understand your options, and choose a safe next step. It does not cover DIY repairs. Gas appliances must only be assessed, repaired, or serviced by a licensed gasfitter.

AGN is a distributor, not a retailer or gasfitter. We manage the gas network that delivers gas to your meter - your retailer handles billing and a licensed gasfitter handles appliance work. We're here to help you understand what might be happening and connect you with the right support quickly.

Key Summary

• Emergency Action: Stop troubleshooting immediately if you smell gas. Call the 24-hour gas emergency line on 1800 427 532 from a safe distance.
• Supply outages: Instantaneous hot water has electric ignition – so power outages will affect their operation. Check both your electricity and gas supply before assuming your appliance has a fault.
• Safe Resets: If there is no smell of gas and your modern system refuses to ignite, you can try switching it off at the power point, waiting 30-60 seconds, then switching it back on. Do not attempt to access or adjust any internal components yourself.
• Professional Help: You must call a licensed gasfitter to fix leaks, clear error codes, or fix water that is dangerously hot. DIY gas work is illegal and highly dangerous. 

If You Smell Gas or Suspect a Leak

No Hot Water?

Before assuming your appliance has failed, it is worth checking whether the problem may be supply-related.

Gas Interruptions and Outages

Planned and unplanned gas network outages can affect your hot water system. Check your gas supply if your hot water stops suddenly with no warning signs. Other gas appliances like your cooktop may also stop working. Your neighbours may experience the exact same problem.

Check your letterbox or gas meter for a notification card. If you haven't received a notification card you can visit the AGN Home Supply page or contact AGN directly to check whether a supply interruption is affecting your area before calling a gasfitter.

Power outages can affect some gas hot water systems, particularly instantaneous gas hot water systems that rely on electricity for ignition and internal controls. They would not work during a blackout even if your gas supply is perfectly fine. You can check your local electricity distributor's website for current power outages in your area.

Your hot water may not return immediately once the power comes back on. You can try a simple reset before calling a professional. Here's what to do:

• Turn the hot water unit off and unplug it from the power point.
• Wait 30 to 60 seconds.
• Plug the unit back in and turn the power on.
• Run a hot water tap inside your home for 20 to 30 seconds.

Appliance Issues

If your gas supply is on and you still have no hot water, the issue may be within the hot water system itself.

For gas storage systems, check whether the pilot light is alight. If it has gone out, follow the manufacturer’s relighting instructions located inside the service panel. Do not attempt to relight the pilot light if you can smell gas.

If the pilot will not stay lit, the unit has an electronic ignition system, a fault code is displayed, or you're unsure of the problem, do not attempt to repair yourself.

Contact a licensed gasfitter to assess the unit. They are qualified to safely diagnose the fault and advise on the appropriate course of action, whether that is a repair, a service, or replacement.

Hot Water Temperature Problems

Temperature variation can occasionally occur with gas hot water systems and is often linked to how the system is being used rather than a fault.

Do not attempt to adjust internal controls, thermostats, or temperature valves yourself. These components require licensed assessment.

Temperature Fluctuating During Showers or taps

With instantaneous (continuous flow) systems, stable temperature depends on a consistent flow of water through the unit. They require a minimum flow of water to ignite the burners. This varies depending on the size of the system, for example, a 16L system - which heats 16 litres of hot water a minute - has lower requirements than a 26L system.

Common, simple causes for water temperature fluctuation include:

1. Low shower pressure or partially closed taps (increase the water pressure)
2. Water-saving shower heads restricting flow (check how many litres per minute your shower head allows)
3. Multiple taps or appliances being used at the same time. If your hot water heater feeds multiple areas of the home and several appliances are trying to use hot water at once, the system may not have the capacity to heat enough water; for example, a 16L system can’t heat 26 litres of water a minute.

In many cases, adjusting water usage or checking shower fittings can help identify whether flow is contributing to the issue.

If temperature fluctuations continue or are accompanied by other changes such as error codes or unusual system behaviour, contact a licensed gasfitter to assess the appliance.

Do not attempt to adjust internal controls, thermostats, or temperature valves yourself. These components require licensed assessment.

If Water Is Too Hot or Not Hot Enough

If your hot water is persistently too hot, this is not just a comfort issue. Excessively hot water is a scalding risk and should be treated as a priority concern. Contact a licensed gasfitter.

If your water is consistently too cool despite normal supply conditions, note whether the issue affects your whole home or only certain outlets, and whether it has come on gradually or suddenly. This context assists diagnosis.

Do not adjust internal gas system controls, thermostats, or temperature components in an attempt to resolve either problem. Assessment by a licensed gasfitter is required.

Water Leaks Around the Hot Water System

Your gas hot water system features a temperature and pressure relief (TPR) valve. It's designed to safely release excess pressure from the system. An occasional release of water from a TPR valve is a sign the valve is doing its job. However, a continuous drip or steady stream from the valve is not normal and requires assessment by a licensed gasfitter or plumber. 

Other visible leaks from your system can range from a minor issue to an urgent situation. Treat significant leaks or rapidly pooling water as an emergency. You must follow the gas leak steps at the beginning of this guide if the water leak is accompanied by a gas smell.

Always contact a licensed gasfitter or plumber to assess a constant leak. Don't try to tighten fittings, seal connections, or isolate internal components yourself.

You can turn off the cold water supply to your property at the mains to reduce damage if the leak is severe. Only do this if you are confident, you can do it safely. Never perform any work on the hot water unit or its gas connections directly.

When to Call a Licensed Gasfitter (and When to Call Emergency Services)

What Information to Gather Before You Call for Help  

Having clear information ready will help the right support pathway assess your situation quickly.  

Could This Be a Servicing Issue or a Replacement Issue?

If your hot water system is experiencing recurring faults, repeated temperature problems, or a noticeable decline in performance particularly in an older unit it may be worth having a broader conversation about servicing or replacement.

A licensed gasfitter can advise you on whether the unit can be repaired cost-effectively or whether it has reached the end of its serviceable life. This is not a decision that needs to be made based on symptoms alone.

For more information, see our guide on Gas Hot Water Servicing and Gas Hot Water System Replacement. 

Important information 

This article is general information only. It does not constitute safety advice specific to your appliance, home, or circumstances. Always follow your appliance manufacturer's instructions and engage a licensed gasfitter for all gas-related repairs, servicing, and assessments.

For supply checks or to report a gas outage in your area, contact Australian Gas Networks on 1300 001 001. For appliance faults, please contact a licensed gasfitter.

All information provided in this article was correct at the time of publishing (May 2026) 

Want to know more? Give us a call on 1300 001 001 or click here to learn more about the gas connection process.