Is Your Hot Water System Too Hot? Dealing with Overheating Issues in the Melbourne Summer

Melbourne’s summer heat can push your hot water system too far. Spot overheating early and know when to call for quick, safe hot water repairs.

The 2025-26 summer in Melbourne is tipped to be another hot one (even hotter than usual). At the height of January and February, everything will be pushed to its limits, including your hot water system.

If your taps are blasting scalding water, you hear strange noises from the tank, or notice fluctuating temperatures, your hot water system may actually be overheating. It’s easy to play these off and think it’s nothing to worry about, but trust us when we say that you’ll want to take it seriously!

Below, we’ll touch on how to respond, why this might be happening, and other signs it’s time to call us in for hot water repairs.

Warning Signs to Watch For

Since overheating is a fairly unique issue in the world of hot water repairs, it’s important to differentiate how the warning signs will play out. These are the usual signs that something is wrong:

• > Scalding taps: Water that’s far hotter than expected often points to a thermostat or mixing valve problem.
  
• > Fluctuating temperatures: Sudden swings between cold and hot suggest that heating controls aren’t functioning properly.
  
• > Rising bills: Overheating and inefficiency can lead to noticeable spikes in electricity or gas costs.
  
• > Strange noises: Popping, banging, or rumbling indicate sediment interacting with the heating element.
  
• > Leaks or dripping valves: Excess pressure caused by high temperatures can result in leaks at the tank or pressure relief valve.
  
• > Discoloured water: Rusty or metallic water signals internal corrosion, often accelerated by repeated overheating.

Even small warning signs shouldn’t be ignored. Acting early prevents bigger, more expensive problems and keeps everything safe. At MCN, we’ve got licensed plumbers ready to help with hot water issues in Armadale, Epping, Nunawading, and the rest of Melbourne.

Common Causes of Overheating

Nailing down the exact cause can be challenging without a professional inspection, but there are a few common factors that contribute to this issue. Let’s take a look:

Thermostat failure is typically the most common cause of overheating. If the thermostat no longer sends the correct signals to the heating element or gas burner, water will continue heating beyond safe levels.

A blocked or corroded pressure relief valve is another frequent problem. Its job is to release water when pressure rises, but if it can’t function properly, water temperature can climb to dangerous levels.

Sediment build-up at the bottom of the tank is a silent issue in many Melbourne homes, particularly in areas with hard water. Minerals like calcium and magnesium settle and trap heat near the element, forcing it to work harder.

Other factors include worn heating elements, gas burners that have lost efficiency, and issues with the original installation. All of these can prevent the system from controlling temperature effectively, creating overheating problems that range from mildly annoying to serious safety risks.

How Summer Affects Our Hot Water Systems

Melbourne summers put extra demand on hot water systems. This could be from more frequent showers, frequent dishwashing, filling pools, or generally being around the house more. It’s at these times when older units (or systems that haven’t been serviced) really struggle under this load, and heat regulation can become unreliable.

High ambient temperatures also affect water storage tanks. When the surrounding air is already warm, the tank retains more heat, and this pushes the system closer to unsafe limits. Summer breakdowns are often avoidable when the system is maintained and inspected regularly.

Troubleshooting Your Hot Water System

Some overheating problems are straightforward to identify without specialist tools:

• > Check the mixing valve: If water at the tap is hotter than the tank setting, the valve may need adjustment or replacement.
  
• > Listen for unusual sounds: Popping, banging, or rumbling indicates sediment build-up. Flushing the tank reduces these noises and helps control temperature spikes.
  
• > Inspect the pressure relief valve: A valve that fails to open allows dangerous pressure to build.

DIY repairs are risky, especially with gas or electric systems. It’s safer to have professionals handle inspections and adjustments to make sure the system operates correctly.

Tips to Manage Overheating During Summer

Even a healthy system benefits from these simple steps:

• > Adjust thermostat settings: 55–60°C is usually sufficient for domestic needs.
  
• > Flush the tank regularly: Removes sediment and prevents hotspots.
  
• > Check the pressure relief valve: Ensure it opens and closes properly.
  
• > Schedule professional servicing: Every 1–2 years, depending on water quality and usage.
  
• > Plan replacement if needed: Systems near the end of their life or showing multiple warning signs are safer replaced than repaired repeatedly.

These measures help your system run efficiently, last longer, and remain safe throughout the hottest months.

The Value of Routine Maintenance

Without a doubt, the best way to prevent issues like overheating from occurring is booking in an inspection. This is equally important for homeowners that live in their property, and landlords leasing it out to tenants.

During a servicing inspection, licensed plumbers will be able to test the thermostat and heating elements, flush out the tank, check pressure valves, and assess other key components. Please note that if you own a system running on gas, the plumber will need to have the relevant certification.

When Replacement is the Better Option

Sometimes, the best option is to bite the bullet and opt for a brand-new hot water system installation. Hot water systems over 8–10 years old, or units showing multiple warning signs like inconsistent temperatures, leaks, strange noises, discoloured water, are often better replaced than repaired.

Replacing an old or unreliable system reduces the risk of overheating, lowers energy consumption, and prevents unexpected breakdowns during peak summer use.

Here’s a breakdown of what’s out there, and which might suit your home!

1. Conventional Storage Systems (Gas or Electric)

These are what most people picture when they think of a “hot water tank” — a big cylinder sitting somewhere (often outside or on the roof), holding a large volume of water.

• > Gas Storage: Traditional and reliable. Brands like Rheem and Dux lead the pack. Rheem offers strong after-sales support and a wide selection of gas storage options.
  
• > Electric Storage: Great if you don’t have (or don’t want) gas. Dux is known for dependable electric systems at competitive prices.
  
• > Compact Storage / Instant-Use: If space is tight, Stiebel Eltron offers compact models that give you hot water without needing a huge tank.

2. Instantaneous (Continuous-Flow) Systems

These systems don’t store water – they heat it on-demand. So when you turn on a hot tap, water gets heated immediately as it flows through. That means potentially endless hot water (or until the gas or electric capacity is maxed out).

• > Rinnai specialises in continuous-flow gas units, which are efficient and sleek.
  
• > Bosch also makes compact and efficient instantaneous gas heaters – ideal if you want something small but powerful.

3. Heat Pump Systems (Electric)

If you’re thinking about electrifying your household or simply reducing running costs, heat pump systems are a great pick. These use electricity to pull heat from the air or ground to heat water, rather than generating heat directly.

• > Stiebel Eltron makes German-engineered heat pump models that are quiet and very efficient.
  
• > Rinnai, Dux, and Bosch also have options, depending on capacity and whether you want a tanked system or not.
  
• > Heat pump rebates in Victoria make this switch even more attractive.

4. Solar-Boosted Hot Water Systems

Victoria currently supports and encourages households to move away from gas, and there are several rebates available to help cover the cost of upgrading to electric heat pumps or solar hot water systems.

Key incentives include:

• > Victorian Energy Upgrades (VEU) Program
• > Solar Victoria Hot Water Rebate – up to $1,000 off
• > Small-Scale Technology Certificates (STCs)

Switching to electric saves money, cuts emissions, and future-proofs your home.

Stay Safe with MCN Plumbing

Hot water overheating isn’t something to ignore, and it’s the last thing you want to deal with on a boiling hot summer day. As soon as you notice the warning signs, give us a call and we’ll send our friendly hot water service plumbers straight to your door!

Here’s what we bring to the table:

• > 24/7 Emergency Plumbing & Fast Same-Day Services
• > Upfront Pricing with No Hidden Costs
• > All Plumbing Work Fully Guaranteed
• > Qualified, Insured & Experienced Professionals
• > No Mess, No Fuss Service
• > 30+ Years of Industry Experience
• > Proven 100% Success Rate with 5-Star Reviews

We offer installations, maintenance, and hot water repairs across Melbourne, all handled by fully licensed and insured plumbers with years of hands-on experience. Get in touch with MCN Plumbing today–call before 10AM and take advantage of our same-day service!