Hot water not working? Here are 5 reasons why & what to do

Hot water system not working? You are certainly not alone and we understand your frustration. There are a few reasons why homeowners should know what causes a water heater to stop working, some of them below – 

  • Be safe than sorry! Act quickly to prevent more serious problems in connected wiring or gas systems.
  • Be better informed when talking to a professional for repairs or replacement.
  • Possibly you can resolve the issue yourself.

No one likes cold showers! We know hot water emergencies need to be dealt with straight away, so when your water heater has completely conked it, the first step is to locate the cause. There are multiple reasons for hot water to stop working, or it could be a combination of factors. This article explains some of the most common causes of hot water systems not working.

Faulty heating element 

A faulty heating element can be one of the causes of your water heater not working. This can affect electric hot water systems and can be the result of one of the following reasons:

  • Mineral deposits gather on the heating element causing malfunctioning. In this case, the tank needs to be flushed and the element to be checked for build-up of scale that covers the copper metal. The element most often needs to be replaced.


  • Air pockets in the tank may cause the element to burn out in exposed air. The heating element should be completely immersed in water. An air pocket can form if the tank hasn’t been flushed completely before filling it in again. This allows an air pocket to form inside the water heater.


  • Power surges can also burn out the heating element. Surges of electricity can also burn out wiring and the heating element. If you suspect this, check the wiring in your home for tripped fuses and call a professional if unsure. In any case, the element will need to be replaced.


  • Cracks in the tank can also extend into fractures in the heating element which stop it from working. The entire water heating unit including the element needs to be replaced. This can be checked visually both before and after flushing the tank. Call a professional plumber for that. Visit our hot water system repair blue mountains, for more information on hot water services.

Faulty TPR valves 

TPR valves stand for temperature/pressure relief valves. They are safety devices designed to release water only if temperature or pressure meets the safety criteria. 

Tempering valves are anti-scalding devices that mix cold and hot water. If this safety device fails, a burning hazard is presented. In most cases, the hot water system will stop working. Read more about tempering valves here. 

Pressure-limiting valves are isolation valves that reduce the pressure of the water. All water heaters are rated to a certain pressure (in Australia 500kPa), and a pressure-limiting valve makes sure it doesn’t exceed that safety level. If the pressure is too high it can cause damage from the water hammer and reduce the life of your appliances. 

Commonly, rust buildup inside the tank starts to block the outlet of the heater and restrict the water flow. The entire hot water unit will eventually shut down. The solution is to replace the faulty TPR valve. 

Proper tools are required to remove the valve, and a replacement part needs to be purchased from the original manufacturer or a reputable plumber. This needs to be fitted securely by a professional.

The Pilot Light has gone off (gas hot water systems only)

The pilot light is a small flame which lights the main burner whenever the water in the tank needs heating, and it should temain alight. Sometimes the light goes out because of a gust of wind, obstructions in the gas opening or when a gas pipe has become undone.

If the pilot light has gone out for some other reason such as windy weather, then it can be relit by the homeowner. You can find the instructions for relighting the pilot light either on the inside of the panel that covers it or on the heater itself. For most of the gas water heaters in Australia, the process is quite easy, however, it’s important to follow the procedure to prevent a buildup of gas which if ignited can cause serious injury. You can watch videos on how to reignite your pilot light here.

Before even attempting to reignite your pilot light ensure all flames and ignition sources are removed.

Step 1. Remove the access panel which is usually at the bottom of your gas water heater. The instructions for the relighting are usually at the back of the cover.

Step 2. Ensure there is no gas leak. This is best done by smelling for gas, especially down the heater where gas can accumulate. If you smell gas, turn the gas control knob off and shut off the isolation valve on the gas water heater. Pick up the phone and call a professional gas fitter for help.

Step 3. Once you have confirmed there is no gas leak, turn the gas control knob fully clockwise until you hear the knob click into the off position.

Step 4. Wait 5 minutes for any unburned gas to escape. If you do not wait full five minutes, residual gas may ignite and cause serious injury.

Step 5. Turn the control knob to the pilot position. This should look like a starburst, press the control knob fully and hold it down to allow sufficient gas to flow to the pilot light. While keep holding the control knob down, start pressing the igniter button repeatedly for about 40 seconds. At this point, the pilot light should be alight, but it is important to continue to hold the control knob down for another 20 seconds. Release the control knob and check if the pilot light remains on. You should see a very small blue flame under the gas control.

gas hot water not working - igniter button

If the pilot light is not alight, get in touch with a skilled technician. Call Ironclad Plumbing Blue Mountains today and one of our professional gas fitters will come to your home to inspect your gas water heater. We service Penrith too, so if you have problems with your hot water system in Penrith, give us a call.

Faulty Thermocouple 

The thermocouple is a safety device that prevents unburned gas to accumulate and as a result, exploding. In gas water systems heat from the flame generates an electric current when two different types of wires are brought together. This thermoelectric current helps thermocouples regulate and keep open the gas valve. If you relight the pilot light and the thermocouple does not start to work, then the problem lies with a faulty thermocouple.

Replacing the thermocouple is the most viable option and this must be done by a reputable plumber.

Leaking tank

Another reason for a water heater to stop working is a leaking tank. This is the most obvious cause and signs of pooling water around the base, damp areas around the unit, and even mould growing show that you have a leaking water heater. If the leakage is not coming from the TPR, or the connection valve then the solution often requires a full replacement of the tank as leakage would then indicate a crack probably from corrosion in the structure of your tank.

Rest easy if you suddenly need to deal with your hot water system not working and call Ironclad Plumbing Blue Mountains. Call us on 02 4760 0441 to schedule a hot water system repair or new installation.

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