Gas Hot Water Not Working: Troubleshooting & Maintenance Guide

While both electric and gas hot water systems are reliable, they require regular maintenance to operate efficiently—especially if your gas hot water isn’t working. If you’re getting cold water from your gas hot water system, here are some simple troubleshooting steps you can follow before calling in a professional.

Before You Start: Check the Basics

Before diving into complex troubleshooting, check the following simple items, including your cold water supply and hot water unit:

Understanding Gas Hot Water Systems

Gas hot water systems are a reliable and energy-efficient way to provide hot water in many Australian homes. They generally come in two main types:

• Instantaneous (Tankless) Systems: These heat water only when needed, offering continuous hot water without a storage tank. They are energy-efficient and space-saving.
• Storage Tank Systems: These store heated water in an insulated tank for immediate use. While slightly less energy-efficient, they tend to be more affordable to install and are common in many homes.

Regardless of the type, gas hot water systems require periodic maintenance to ensure they continue running smoothly. If you’re having issues with your hot water tap or suspect a problem with your system, use these troubleshooting tips before contacting a professional.

Safety Precautions

Gas appliances—especially those with pilot lights—come with inherent risks. Before attempting any checks or repairs, follow these safety steps:

• Turn off the gas supply: Locate your gas shut-off valve and switch it off.
• Ventilate the area: Ensure good airflow in case of a gas leak.
• Avoid flames or electrical devices: Do not use open flames or operate appliances near a suspected leak.
• Call a licensed plumber or gas fitter: For anything potentially hazardous, get professional help straight away.

Basic Troubleshooting Checklist

Check the following components first, as many common issues relate to these:

• Gas supply: Make sure the valve at your gas meter is on. If other gas appliances are working, the issue may be with the hot water system alone.
• Pilot light: If your system uses a pilot light, check if it’s lit. If not, follow the manufacturer’s instructions to relight it.
• Power supply: For systems with electronic ignition, confirm the unit is plugged in and switched on.
• Water supply: Ensure your main water valve is open and there are no water supply disruptions.

Common Gas Hot Water Issues and Fixes

1. Pilot Light Keeps Going Out

This may be caused by:

• A faulty thermocouple
• A dirty or blocked pilot orifice
• A gas supply issue

Solution:

• Clean the pilot light assembly with a soft brush or compressed air.
• Replace the thermocouple if necessary.
• Check for any disruptions in the gas supply.

2. No Hot Water

This might be due to:

• A faulty thermostat
• A clogged gas line
• A failed heating element in hybrid systems

Solution:

• Reset the thermostat and allow time for the water to heat.
• Inspect the gas line and clear any blockages.
• If using a hybrid system, check electrical components and reset as needed.

3. Lukewarm Water

This may be caused by:

• Sediment buildup in the tank
• A partially open gas valve
• A malfunctioning thermostat

Solution:

• Flush the tank to remove sediment.
• Make sure the gas valve is fully open.
• Test and replace the thermostat if required.

4. Low Water Pressure

This might happen due to:

• A blocked filter or strainer
• Incorrect gas input levels
• Pipe corrosion or mineral build-up

Solution:

• Clean or replace filters.
• Check and adjust gas pressure.
• Inspect and replace old or damaged pipes.

5. Gas Leaks

Signs include:

• A rotten egg smell
• A hissing sound
• Visible damage to pipes

Emergency steps:

• Turn off the gas immediately.
• Ventilate the area by opening windows and doors.
• Avoid using electrical devices or flames.
• Call a licensed plumber or your gas provider.

6. Cold Water or Delays in Heating

This may be due to:

• Incorrect thermostat settings
• Issues with recirculation pumps
• Flow rate issues in tankless systems

Solution:

• Raise the thermostat temperature slightly.
• Confirm recirculation pumps are working properly.
• Increase water flow to activate tankless units.

Preventative Maintenance for Gas Hot Water Systems

Regular servicing by a qualified gas technician helps avoid issues and extend your system’s lifespan. Maintenance tips:

• Inspect pilot light and burner: Remove dirt or debris and check for stable flames.
• Flush the tank yearly: Removes sediment and improves efficiency.
• Check for leaks: Regularly inspect gas lines and joints.
• Test pressure relief valve: Lift and release to confirm correct operation.
• Annual professional service: A licensed plumber should inspect your system at least once a year.

When to Call a Licensed Plumber

Contact a professional if:

• You smell gas or suspect a leak
• The pilot light keeps going out
• Water temperature fluctuates unpredictably
• The system makes unusual sounds
• You notice rust, corrosion, or physical damage

Avoid DIY repairs for complex issues like blocked strainers or damaged valves. It’s always safer to engage a qualified professional.

How to Reset a Gas Hot Water System

If issues persist, try resetting the system:

1. Turn off the gas supply at the shut-off valve.
2. Wait a few minutes to allow gas to dissipate.
3. Relight the pilot light as per the manufacturer’s instructions.
4. Check thermostat settings and adjust if necessary.
5. Turn the gas supply back on and monitor the system.

If you use LPG and notice signs like a faint blue flame or sputtering, your gas bottle may need refilling. Contact a technician if unsure.

Final Thoughts

A malfunctioning gas hot water system—whether tankless or storage—can be frustrating, but many problems can be resolved with basic troubleshooting. When in doubt, safety should always come first. If you’re unsure, uncomfortable, or notice persistent issues, reach out to a licensed plumber or gas fitter.

With regular servicing and proactive maintenance, gas hot water systems can deliver reliable, cost-effective hot water for years. If you’re considering an upgrade, tankless or hybrid systems are great options. These newer models save space, reduce energy consumption, and offer improved long-term performance—especially when paired with advice from your gas utility provider.