Having hot water is essential in our daily lives. So when you find your gas hot water not working, it can be very frustrating.

No need to worry, though! Below is a guide that will help you troubleshoot and fix your gas-powered water heater. From the three most popular types of gas hot water systems in Australia to a few great maintenance tips, we’ve got you covered. Let’s get cracking!

Popular Types of Gas Hot Water Systems

You must understand the different available types to properly deal with your gas hot water not working. Most Australian households have the following:

  • Storage Tank Water Heaters
  • Instantaneous Water Heaters
  • Continuous Flow Water Heaters

What are Storage Tank Gas Hot Water Systems?

Unlike other available products, this heater comes with its own tank. The beauty of heaters with tanks is that they allow you to save hot water for later use.

This type of heater is perfect for households with high hot water demand. However, bear in mind that the tank’s capacity will determine how much water you can store in it.

How Do Storage Gas Hot Water Systems Work?

This system stores cold water in a built-in tank, usually from the bottom up. The unit’s gas burner will then start heating the water, causing it to rise and flow towards the tap.

Upon opening the tap, hot water will come out, and cold water will enter the tank again from the bottom. This ensures that the tank is always full.

What are Instantaneous Gas Hot Water Systems?

Instant gas-powered water heaters have become increasingly popular due to their space-saving design and sheer energy efficiency. A study by Boait, P., Dixon, D., Fan, D., & Stafford, A. (2012). on the production efficiency of hot water for domestic use, found that instantaneous production of hot water is much more efficient than delivery via tank storage for gas-fuelled systems. By not relying on tanks, they can produce hot water without resulting in heat loss.

This type of heater is excellent for households with minimal demand for hot water. Plus, they take up less space since they don’t have built-in tanks.

How Do Instant Gas Hot Water Systems Work?

Also known as tankless heaters, instantaneous gas-powered systems allow you to get hot water on demand. Just turn the tap on, and the unit will do the rest by ensuring water passing through its plumbing is warmed to your desired temperature.

This real-time heating helps ensure you enjoy hot water whenever needed. Some systems even feature advanced sensors, allowing them to monitor water flow, adjust the burner’s heating capabilities, and maintain consistent temperature.

What are Continuous Flow Gas Hot Water Systems?

Similar to instantaneous heaters, this system provides hot water on demand and comes with no built-in storage tanks. Its main difference lies in its water flow rate, which remains the same even if you turn on multiple taps simultaneously.

Continuous flow heaters are best for hot water use in small or medium-sized households of up to 5 persons. If more people live in your home, you’ll need more than one system to meet the demand.

How Do Continuous Flow Gas Hot Water Systems Work?

Like instant heaters, continuous systems heat the water passing through its tubes. However, it has a flow sensor that will then regulate the water flow rate and adjust its burner’s intensity. These tweaks will result in hot water flowing through multiple outlets at the same speed and temperature.

Why is My Gas Hot Water Not Working?

Like electric-powered heaters, gas hot water systems have their downsides. A study by UTS Institute for Sustainable Futures on Domestic Hot Water and Flexibility found that “While the average user of gas hot water had lower annual bills than those with electric water heating in 2020, by 2030 they were projected to be significantly worse off“. Additionally, they’re vulnerable to many issues, including:

Cracked or Damaged Storage Tank

This can result from the tank being worn down over time or the water pressure getting too high. Left unaddressed, it can lead to poor or no hot water flow and other issues.


To resolve this issue, inspect the tank from top to bottom. Seal minor cracks and openings with suitable sealants. If the damage is beyond your abilities, get help from a professional.

Inconsistent Water Temperature

This problem can be due to a malfunctioning dip tube or a faulty thermostat. In the former’s case, cold water is mixed with hot, resulting in lukewarm temperatures.

Meanwhile, the latter will lead to your unit not regulating the temperature produced by the burner. This will result in the water becoming too hot or too cold to your liking.


You must inspect the dip tube or thermostat to resolve this issue. If either (or both) are broken, have them replaced immediately. If it’s just the settings, adjust it to your preferred temperatures.

Sediment Buildup

Water contains minerals that will form sediments within the heater’s plumbing. This will gradually accumulate, resulting in poor water flow.


To fix this, remove the sediments within your heater’s pipes. Start by draining your system. Then pour vinegar in it, close the drain valve, and let it soak inside the unit for around 6 hours.

Overloaded System

This usually happens when too many people are using the heater simultaneously. At the very least, it can result in less hot water produced. Worse, it can lead to your unit breaking down.


To prevent this issue, refrain from overusing the hot water system. If it’s already damaged, call your HVAC professional to have it fixed ASAP.

No Pilot Light

The pilot light is crucial for the operation of gas hot water systems. If it goes out, the burner won’t ignite, and there won’t be any hot water. This could be due to drafts putting the light out, an empty gas tank, or a faulty pilot tube.


Open the access panel and look for the pilot light (it’s a small blue flame). Alternatively, you can use a stethoscope and listen to the light’s sound.

If you can’t see or hear anything, turn off the gas valve, wait a few minutes, and switch it back on. You should also check if there’s wind flowing through the burner or if the gas tank or pilot tube is to blame. Consult your trusted HVAC expert if the pilot light still doesn’t reignite.

Faulty Thermocouple

This safety device is responsible for detecting the pilot light’s flame. If it malfunctions, the heater might automatically shut down the gas supply to prevent leakage. This will result in your gas hot water not working despite the presence of a pilot light.


Again, open the access panel and check the thermocouple’s status. If it’s damaged or improperly positioned (its tip must be near the pilot light), consider replacing or reorienting it.

Maintenance Tips for Your Gas Hot Water Heater

Proper maintenance is essential to ensure your gas-powered heater’s longevity and performance. By following the tips listed below, you can prevent potential issues from arising in the future and enjoy a consistent hot water supply.

Regularly Check the Pilot Light

The pilot light is a crucial component that ignites the burner to heat the water. Periodically inspect the pilot light to ensure it’s burning steadily. If you notice any flickering or the pilot light going out frequently, it might indicate a problem that requires attention.

Test the Pressure Relief Valve

The pressure relief valve prevents excessive pressure from building up within the tank. Test it by lifting the lever and allowing some water to discharge. If no water comes out or the valve leaks after testing, it might be time to replace your hot water heater.

Drain and Flush the Tank

Sediment buildup can affect the efficiency of your heater and lead to various problems. Drain and flush the tank at least once a year to remove sediment and minerals accumulated at the bottom.

Adjust the Temperature

Set the thermostat temperature to a safe and comfortable level. Very high temperatures increase the risk of scalding and accelerate the tank’s mineral buildup.

Inspect for Leaks

Regularly check around the heater and connections for any signs of water leaks. Catching leaks early can prevent water damage and more extensive repairs.

Ensure Proper Ventilation

Adequate ventilation is crucial for the safe operation of your gas heater. Ensure the area around the heater is clutter-free and the vents are unobstructed.

Schedule Professional Maintenance

While many maintenance tasks can be done by homeowners, having a professional inspect and service your gas hot water heater annually is recommended. They can catch issues that might not be apparent and ensure all components function correctly.

When to Contact a Professional Plumber

Whilst some hot water repairs are complicated, there are a few issues that can be addressed with DIY solutions. However, some situations require professional expertise. These include:

Persistent Pilot Light Issues

If your pilot light refuses to stay lit despite repeated attempts, it’s time to call a professional. A plumber can accurately diagnose whether the issue is with the thermocouple, gas supply, or other components.

Gas Leaks or Strange Odours

If you smell gas near your water heater or suspect a gas leak, immediately turn off the gas supply and contact a plumber. Gas leaks are hazardous and should be addressed by a trained professional.

Poor Performance Despite the DIY Fix-Up

If you’ve followed basic troubleshooting steps and your gas water heater still has problems, it’s best to call a plumber. Complex issues, such as faulty gas control valves or burner problems, require specialised knowledge to resolve safely.

Unusual Noises

Strange noises like popping, rumbling, or banging from your water heater could indicate sediment buildup or other internal problems. A plumber can inspect the heater, flush out sediment, and perform necessary repairs.

Big Water Leaks

If you notice water pooling around the base of your water heater, it might indicate a leak in the tank or connections. Leaks can cause water damage and potentially compromise the heater’s functionality.

Unpredictable Temperature

If your water temperature fluctuates unpredictably, it could be a sign of a malfunctioning thermostat, gas valve, or other components that require professional attention.


If you find your gas hot water not working, you must address the problem immediately. By following the tips listed above, you can quickly resolve any issues plaguing your water heating system and prevent future problems.

So get your peace of mind back, follow our guide, and get the hot water you and your family deserve.