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How to Reignite Gas Hot Water Systems

There’s nothing like the feeling of getting everything sorted for your night-time routine, only to realise that your water is running cold.

You wouldn’t be the first person who has performed a sudden scramble to get their gas system back up and running in time for guests or a tired child’s bath time.

We’ve listed some of the top things to consider the next time your gas hot water begins to run cold, so you can approach the situation armed with the knowledge of how to get your gas hot water flowing perfectly again.


It all begins with the pilot light

a flame representing a gas pilot lightIf you own a gas hot water system, you may already know that igniting the pilot light allows the gas burner to convert warmth to hot water.

Usually, the first warning that something is wrong with your pilot light is cold water running from the tap. A pilot light can malfunction for a few different reasons including storms and extreme weather, a blockage, an empty gas cylinder, an equipment malfunction, or issues with the gas main pressure.

The good news is that if your pilot light goes out, it is possible to reignite it yourself, making your hot water repair a simple task.

Start by finding the gas regulator valve on the outside of the water heater where the gas pipe enters the system. This valve is responsible for regulating the flow of gas to the pilot burner and is easily accessible.

Once you’ve found the valve, ensure it is turned on. The handle of the valve will be parallel for on and perpendicular for off. You will then have the ability to go through the lighting procedure which is usually on the inside of the cover plate.

Now, what you can see in front of you is the gas controller which takes care of lighting the pilot, regulating gas pressures and controlling temperatures.



The following instructions are from the Rheem gas owner’s hand book:


1. Stop, read the safety information on page 41.

• Remove the access cover.

DANGER: If the main burner or pilot flame is extinguished for any reason during the lighting process, ALWAYS turn the gas control knob to the “” (off) position and wait 5 minutes.

2. Turn the gas control knob fully clockwise to the “” (off) position.

3. Wait 5 minutes so any build-up of unburnt gas can escape.

Warning: Failure to wait 5 minutes may result in a fire or explosion.

4. Turn the gas control knob to the “∏” (pilot) position.

5. Depress the knob fully (until the “∏” disappears below housing) and hold the knob down until the end of Step 7. Note: If it is not possible to depress the knob FULLY, turn the gas control knob to the “” (off) position and begin again at step 3.

6. After waiting 30 seconds and with your face clear of the combustion chamber opening, press the igniter

button repeatedly (for up to a further 40 seconds) until the pilot flame lights.

7. Continue to hold the knob down for 20 seconds after the pilot flame lights.

8. Release the knob and check the pilot is still alight – look through the combustion chamber opening below the gas control.

9. If the pilot has failed to light or has not remained alight, turn the gas control knob to the “” (off) position and begin again at step 3.

Note: The next step will cause the main burner to light, if the water in the tank needs heating. The flames may be noisy at first. This is normal and will cease after 2-5 seconds.

10. If the pilot flame remains alight, turn the knob anticlockwise to the numbered setting of ‘5’ for a water temperature of about 60°C. This setting is also shown on the rating label.

11. Turn the knob to a higher number if a higher water temperature is required. Refer to “Temperature Adjustment” on page 13.

12. Replace the access cover

Rheem 170 litre hot water heater

Know what to look for…

Unfortunately, as with any gas appliance, gas hot water systems are susceptible to gas leaks, although it is rare.

If you smell gas coming from your tank or anywhere around the system and within the home, DO NOT attempt to light the pilot light or perform any other work on the system.

Isolate your supply at the gas meter or bottles and phone an emergency plumber immediately.


Some of the main signs that your gas system has sprung a leak include a rotten egg smell, a hissing noise or dead plants or vegetables around the system.

If the above signs are absent but you’re still concerned, you can perform a bubble test by combining soap and water with a cloth and rubbing it over the areas you believe are leaking. If bubbles form in these areas, there is likely a leak present.


Does your gas hot water system need a reboot?

The old trope ‘have you tried turning it off and on again?’ can apply to hot water systems.

This is a simple trick that you can perform on your own safely, saving the call-out fee for a plumber.

Sometimes, due to human error or equipment malfunction, your gas hot water system may simply be turned off or the water supply is halted.


5 steps for restarting your gas storage hot water system:

1. Turn on the water supply using the cold-water inlet control valve at the bottom of the system or the mains water supply of the property.

2. Test that the water is flowing by turning on a tap inside the property and flushing out any residue. The water should eventually flow evenly without spluttering or spitting.

3. Turn on the gas valve at the bottom of the system. Set the temperature gauge to the lowest setting and switch the regulator valve to an off position. Wait 10 minutes and turn the switch back to pilot mode.

4. Ignite the pilot light using the above instructions.

5. Set the temperature control and switch the heater’s main burner to on. The standard temperature is usually set between 50 – 65 degrees. You should now be able to hear the system coming to life and heating the water.


If you have an instantaneous gas hot water system, restarting the system is simpler:

1. Turn off the electrical supply next to the water heater.

2. Switch off the gas supply at the gas shut off valve. Wait five minutes and ensure there is no gas smell.

3. Turn on the hot water taps connected to the system and run them to flush air out of the system.

4. Turn the power supply and gas back on.

5. Set your desired temperature or leave it be if the system has specific internal settings.

If your water begins to flow at your desired temperature, and if you didn’t notice any gas leaks, hissing or strange sounds coming from your machine – generally you should be free to enjoy your hot water after a system reboot.



Some simple maintenance can go a long way

As with any important appliance that goes through regular daily use, a periodic maintenance routine can add reliability and durability to the system. Regular maintenance can double the life of your system. Without such maintenance, your system may be susceptible to a build-up of air or sediment, worn-out elements, or misalignment.

The best way to determine how to service and maintain your hot water system is to consult your user manual or call our 24/7 emergency plumbers at 1300 721 996

This will ensure all steps are followed so your maintenance is safe and effective. Aspects such as cleaning the burner, adjusting the air shutter, and replacing the thermocouple can be complicated to complete yourself and its best to leave these to a professional.

Checking the temperature + relief valve and sacrificial anode are tasks that should be completed by a professional every six months to a year, ensuring the correct temperature and the right level of water is flowing from your system. If during any of these tasks you encounter too much water coming from the wrong areas, you smell gas or notice extremely hot temperatures, it may be time to call a professional to replace or install a new hot water system for your home or business.


Replacement or repair, we can help…

When it comes to hot water systems malfunctioning, it is usually at the most inconvenient time when many people are needing showers, or you’ve just welcomed an array of guests to stay for the weekend. That’s where we come in.

With same-day delivery and a 24/7 emergency plumbing hotline, we can keep you in perfect hot water around the clock. Whether you need a complete replacement of your gas hot water system, or if something is just not working how it should, we will have the solution for you.

Call our experienced and friendly crew on 1300 160 956 or send an enquiry our way.

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