Absolute Airflow Heating and Cooling

Signs You Need A New Hot Water Service Unit

Aug 14, 2024 Hot water unit installed in a home

You might not realise you need a new hot water unit until it’s too late! Hot water units are essential to modern living, and we need a functional system for cleaning and staying comfortable, both at home and at work. If it’s time to replace your old hot water unit, it’s best not to delay.

The signs your hot water is on its way out might not always be as obvious as a sudden lack of hot water. However, learning some of the early warning signs can allow you to prepare a unit for swapping over, before you are completely without access to hot water.

With all of that in mind, here are five of the most common signs that your hot water service unit needs to be replaced.

Sign 1: Strange Noises

While your hot water service unit is normally situated outside, away from your common living areas, it’s important to keep an ear out for any strange noises it may be making. Sounds like loud and sudden clunks, hammering, popping or even screeching could indicate problems like sediment buildup, pipes under pressure or loose valves.

Hearing these noises repeatedly means you may need to consult a professional to diagnose and address the problem. A buildup of sediment or pressure can eventually lead to a leak, which cannot always be repaired. If your unit is very noisy, you may need your hot water system replaced, not just fixed!

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Sign 2: Leaks Or Discolouration

If you’ve noticed water sitting around your hot water unit or actively leaking from it, then it’s important to address the problem quickly – sometimes, a leak cannot be fixed and will require a unit replacement.

Leaving a leak alone can cause water damage to your home, so it’s important to find the source of the leak quickly. If a pipe has cracked, or metal has expanded and burst in your hot water unit, a replacement may be necessary.

In some cases the water may even be discoloured, which is normally an indication of rust inside your system. If this rusty water is coming out of your taps, it can actually cause damage to the rest of your plumbing system, so it’s a sign you need a replacement unit immediately.

Sign 3: Inconsistent Water Pressure

If the pressure or flow of your water has become inconsistent and sporadic, it could indicate a buildup of sediment inside your hot water system. Minerals from water can harden and calcify inside the body and pipes of your unit, impacting the flow of water and eventually clogging the flow altogether.

Water pressure can also be affected by how large your household is. If the demands on the water heater are outstripping it, then you may find it cannot produce as much hot water as needed, leading to a reduction in pressure.

Either way, you may need a new water heater unit that can keep up with your hot water needs.
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Broken hot water element

Sign 4: Poor Temperature Control

Enjoying a hot shower and suddenly notice an unpleasant burst of cold? Struggling to get your sink water hot enough to wash your dishes in? Poor temperature control is a sign of a failing hot water unit, indicating that the heating element may have burnt out and is impacting your hot water supply. 

If your pilot light is out or weak, this can be repaired yourself, or you may need to adjust the thermostat. Otherwise, replacing your hot water unit may actually be cheaper in the long term than trying to fix this problem.

Sign 5: Your Unit Is Old

No matter how well you maintain your hot water system, it will eventually need to be replaced. This is because after prolonged use, the inner mechanisms will wear down over time, and older units tend to be less effective and efficient when it comes to water and power usage.

Generally, when your hot water service unit hits 10 years old you’ll need to start looking into replacing it. This number will vary depending on how well you have looked after your hot water unit and what type it is – for instance, electric hot water systems tend to last longer than solar heater ones. Some may even last up to 20 years!

Choosing to install a new water heating unit is a great chance to pick one that is more energy efficient and better suits your household’s water needs.

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What About Hot Water Unit Repairs?

Of course, fully replacing your hot water unit may not always be necessary. Sometimes, a quick repair is all that’s needed – and you may even be able to do it yourself.

Here are some of the smaller hot water problems and checks you can do yourself:

Checking The Sacrificial Anode Rod

Old hot water anod rod

The sacrificial anode rod attracts the minerals and impurities inside your hot water unit, preventing them from making their way through the system to your taps. This causes the rod to degrade over time, and if it is left for too long, the rod will stop being able to attract the minerals which will then start to disperse in your hot water system.


You should check the sacrificial anode rod twice a year to see if it needs to be replaced – do this by turning off the water and power to your system, draining the tank and unscrewing the anode rod from your system. You may have more than one! If it looks like the top rod in the picture above, then it needs to be replaced. If you’re unsure, it’s best to call a professional to do this, as they can supply a new rod and ensure it is fitted correctly in your unit.

Testing The Temperature And Pressure Relief Valve

The temperature and pressure relief valve is an important part of your system that ensures the pressure inside the unit never gets too high. Testing it isn’t hard, but it can be dangerous due to the scalding hot water that will be released when you open the valve.

Make sure you are wearing safety gear (gloves, eyewear, long pants and closed shoes) before locating and opening the valve while standing as far back as you can. You may like to use a bucket to collect the water. Close the valve once some water has come out!

If this whole process happens smoothly, you have nothing to worry about. But if you struggle to open or close the valve, or it drips once closed, it may need a professional service.

Relighting The Pilot Light

Without the flame of your pilot light, your gas hot water heater won’t be able to do its job. Relighting it isn’t hard, but it does have to be done properly for safety reasons.

  1. Turn off the gas to the unit. Wait for ten minutes, as this will allow the gas in the lines of your unit to dissipate. 
  1. Make sure your gas control knob is pointing towards ‘pilot’ and is fully pressed in.
  1. Keep the knob in and press the ignitor button continually for around 90 seconds until the pilot light ignites or a light starts to flash.
  1. Now that the flame is lit, slowly depress the gas control knob and then turn it back to your preferred temperature. Keep an eye on the flame to make sure it stays lit.
  1. Make sure that the light is still flashing – if it’s not, the problem may come back.

If these steps aren’t enough, you may have a more serious problem that needs an expert touch.

Flush Out The Sediment In Your Tank

Cloudy water coming out of your taps may indicate a buildup of sediment in your hot water tank. You can flush it out by turning off any power and water flow to the unit itself, then carefully open the temperature and pressure relief valve to depressurise the system.

Disconnect the cold water supply pipe and attach a drainage hose, making sure the other end of the hose is in a drain. Disconnect the hot water pipe to force water to flow out of your new hose.

Use your garden hose to flush the system with fresh, cold water via the entry port where the hot water pipe was. Continue until the water exiting your system is running clear. Then reconnect everything as it was to finish.

Technician installing hot water unit

Choose Absolute Airflow When You Need A New Hot Water Unit

Do you need to replace your old hater water unit with a new one? Let the experts at Absolute Airflow install a brand-new water heater unit perfect for your home today! Our licensed plumbers also provide repairs and scheduled maintenance services to keep your hot water unit running smoothly.
Feel free to contact us at 03 7036 9149 whenever you need a new hot water unit in Melbourne, or fill out an online request form and we’ll be in touch as soon as we can. For more information on hot water systems, make sure to check out our blogs on How Often Should You Service Your Hot Water Heater and Comparing the Different Types of Hot Water Systems.

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