Inner West and Eastern Sydney Plumbers

Gas Hot Water Troubleshooting

A Little Troubleshooting Can Keep Your Current System Humming

Gas hot water systems

A Little Troubleshooting Can Keep Your Current System Humming

Gas hot water heaters can be long-lasting and reliable with regular attention.

If you’re the handy DIY type with time to spare, you can handle some of the little maintenance issues yourself.

(CAVEAT:  Be sure you can work safely when you’re digging inside any electrical appliance. No one wants to be electrocuted, right?)

Note: If your heater is a single element off-peak heater, be patient.  You’ll need to wait until the morning to know if your troubleshooting has been successful.

Keep in mind…

Heaters aged around 10 years old are approaching the end of their useful life. Once problems start, they keep coming, so it’s a good time to think about a replacement.


Is the problem covered by an existing warranty? Common hot water system warranties might be:

  • 12 mths for components and workmanship
  • 3 – 10 years for continuous flow heaters
  • 5, 7 or 10 years for the tank

Call your manufacturer first. . Repairing or altering yourself will void your warranty so only attempt the following simple checks. If it’s still not working, call your Pipe Perfection plumber.


Troubleshooting Tips for Your Gas Hot Water Heater

Do you have no hot water at all?

If you have no hot water at all, check the main supply of gas to your home.

Go to your cook top, oven, gas heater or gas BBQ (that is connected to the gas supply). Check to see if they light. If so, the issue is definitely with the heater and not the gas supply. Go directly to the next step.

If not, check the gas meter valve (tap) is in the on position (aligned vertically with pipe – see pic on the right). If the gas meter is on and there is no gas, call your utility company.

If the supply to the house is off, you’ve found your problem! 

If the gas shut off is in the off position (i.e. at a 90 degree angle to the pipe), turn it on. There will be air in the gas lines that you need to get rid of FIRST. The fastest way to do this is to light your cook top and wait until all burners have a solid flame around them. Then turn them off.  Your hot water will be ready to go as soon as it’s heated.

Do you have an instantaneous or tankless heater? e.g. Rinnaicheck gas supply

The gas pipe sits at the bottom of the heater on the far right. Turn the tap (it should be yellow) so it is in line with the heater.

Make sure the gas valve or tap to the hot water system is on. In the same way, the valve (i.e. the tap handle) should be in line with the copper gas line.

Also check the continuous flow is plugged into it’s electrical socket. If you have a controller, check that is on and the temperature is set to a high enough temperature.

The gas supply line should be on the left hand side of the tank and have a yellow tap handle. Again, if the tap is vertical, along the line of the copper gas pipe, it is in the ‘on’ position.

The gas supply line should be on the left hand side of the tank and have a yellow tap handle. Again, if the tap is vertical, along the line of the copper gas pipe, it is in the ‘on’ position.

This is a more common problem with storage tanks compared to instantaneous heaters. The ‘how-to’ differs markedly between brands so use  the instructions below as a guide. Better still, consult the owner’s manual and follow those instructions. If you can smell gas around the heater, do not proceed further, turn off the gas supply to your heater and call us to have a Pipe Perfection Plumber help you.

Open up the inspection panel at the bottom of the tank. You might have to slide it up vertically then pull it towards you. It may be screwed shut.

The pilot light should always be on. It is a ground level, you’ll need to lie your head on the ground and look at the very bottom of the heater. There should be a blue flame. If there isn’t, you can try turning it on. But be careful – move your head right back, you don’t want your eyebrows singed!! 

Instructions to turn on the pilot light will be on the back of the inspection panel but approximate directions are:

Turn the control knob (1) to the off position (may look like this •) and wait 5 minutes for any gas to disperse. Then turn the control knob (1) to the pilot position (star shaped).  Hold the control knob down while pushing the piezo ignition switch (2) repeatedly (up to 10 times). Keep holding the control knob down (1) for at least 20 seconds then release the control knob. (Never press the piezo ignition if the control knob is at a numbered position).

Look under the controller (3) to see if the pilot is lit and is holding. Keep your head as far back as possible. If it goes out, turn the pilot button to the off position (•) wait for five minutes again.  Repeat two more times. If it won’t hold, contact Pipe Perfection Plumbers on 1300 00 7473 for help.

Turn the control knob (1) to the flame position and the main burner should ignite. Then turn the pilot button to between position 4-6  which is the normal position for hot water heating (check your instructions as this will differ between brands).

You must turn the water on for the heater to fire up. Turn the water on and have it flowing as fast as it will go. You should hear the burner light and you will smell gas. If it doesn’t light, call your hot water professionals, Pipe Perfection Plumbers on 1300 00 7473.

Cool or not enough hot water?

Possible Cause #1:  Distance between the taps and the heater

It can take some time for hot water to travel to the tap. Let the tap run full on for a good 5 minutes. If hot water comes through eventually, then distance is the issue. A recirculating pump can help with this issue, as will insulating your pipes.

Possible Cause #2: Instantaneous hot water heater flow rate

These heaters require moderate to high water flow to ignite the pilot light. Turn your taps on hard and allow them to run for 5 minutes.  If the hot water starts up, the problem is related to the flow rate of water rather than a heater problem.

Possible Cause #3: Tank size

With storage systems, you can run out if your tank is too small. Most manufacturers indicate the adequate size tank for a certain household. Be aware that spa baths and dishwashers may count as a person.

Possible Cause #4: Thermostat setting

Changing the thermostat may increase the hot water temperature at the tap (unless you have a tempering valve or a temperature limited model). Refer to your unit’s instruction manual (or find it online). Usually you can turn the pilot button to a higher number (see figure used in “is the pilot light on?)

Is your hot water TANK leaking?

Is it leaking from the TPR valve?

It is normal for a small amount water to gently drip from the Temperature pressure relief (TPR) valve while the water is being heated. This occurs as the water is heated and expands by approximately 1/50 of its volume. It should not be constant or all the time. If it is  releasing more than a bucket full of water in 24 hours, call Pipe Perfection Plumbers on 1300 00 7473.

If it is leaking from elsewhere:

A leak from anywhere other than the TPR valve is not normal and needs to be attended to quickly. Turn off the water and gas supply to tank.

Find the pipe closest to the bottom of your unit (=cold water inlet). Turn clockwise the black knob that is fitted to the pipe near the tank. Keep going until it stops. No  more water will enter the hot water unit. Sometimes the leak may continue but it will be significantly slower.

Turn off the gas inlet as well. The yellow tap that is fitted to the pipe near the tap. Keep going until it stops.

Heaters that are nearing 10 years old are approaching the end of their useful life. Once problems start occurring, the most cost effective solution is to replace.

Not sure what the problem is?

Call us 1300 007 043, email us or make a booking to schedule a consultation with your Pipe Perfection plumber.