The water heater's heating element is the component that does all the work – heating cold water to a usable temperature. When this part starts to fail, the water heater usually doesn't completely break down immediately, but rather shows several smaller signs beforehand. Noticing these signs can prevent a major breakdown or a hazardous situation.
Many homeowners and apartment owners in Tallinn and Harjumaa only notice the first changes when there's a shortage of hot water or the electricity bill has skyrocketed, although in reality, the water heater was giving warning signs several months earlier that something was wrong.
In this guide, we'll go through all the most important signs that indicate a problem with the heating element or related parts, explain what you can safely check yourself at home, and what tasks must definitely be left to an electrician or plumber.
Unlike our general guide on water heater cleaning, this article specifically focuses on assessing the condition of the heating element – which symptoms mean limescale build-up, which indicate corrosion, and which signify an outright fault.
Water Heats Up Slower Than Usual
The most common and often first sign of a heating element problem is when the water heater takes significantly longer to produce hot water than before. If the water heater used to be ready an hour or two after being switched on, but now it takes several hours, there's cause for concern.
The main culprit is usually limescale, which builds up in a thick layer on the heating element's surface. Limescale acts as an insulator – the heating element consumes the same amount of energy, but the heat is no longer efficiently transferred to the water; instead, it primarily heats the limescale layer itself.
- Slow heating is especially common in areas with hard tap water – including many places in Harjumaa.
- If the problem develops gradually over several months, it likely indicates limescale accumulation.
- If the problem appears suddenly and completely, the heating element may have already burnt out.
Electricity Bill Has Increased Without Obvious Cause
If the water heater takes longer to heat water due to limescale, it also consumes more electricity to achieve the same result. This is often the first thing people actually notice, even before slow heating.
As the limescale layer thickens, the water heater's energy consumption can significantly increase, as the heating element has to work much longer to reach the same temperature.
How to Differentiate Water Heater Costs from Other Bill Increases?
If the increase in your electricity bill coincides with no change in your hot water usage habits – i.e., your household isn't using more hot water than before – and at the same time, the water heats up slower, the water heater is quite likely the cause. If in doubt, comparing with previous months' bills where hot water consumption was similar can help.
Crackling, Rattling, or Clanking Noises During Heating
If the water heater makes unusual noises during heating – crackling, rattling, or even clanking – it's mostly due to the breakdown of the limescale layer that has accumulated directly on the heating element's surface.
During heating, small water vapour bubbles form between the limescale layer and the heating element, which, as they bubble, create a characteristic noise – similar to a boiling kettle, but louder and more prolonged.
- A soft hum or quiet rumble during operation is usually normal.
- Loud crackling, popping, or clanking indicates a thick limescale layer or pieces of limescale detaching from the heating element's surface.
- If the noise gets louder over time, the amount of limescale is likely increasing, and cleaning or heating element replacement will become inevitable sooner or later.
Residual Current Device (RCD) Trips Repeatedly When Using the Water Heater
This is one of the most serious signs requiring immediate attention. If the RCD in the electrical panel repeatedly trips while the water heater is operating, it means that electrical current is leaking somewhere it shouldn't – most often through the water directly to the earth.
The most common cause is damage to the heating element's insulation, which results in electrical current coming into contact with water. This is a direct safety risk, and the water heater must not be used in this condition until the problem is resolved.
What to Do if the RCD Trips?
Immediately disconnect the water heater from the mains power and do not attempt to switch it back on yourself before the electrics have been checked. This is a situation where an electrician or an experienced plumber with expertise in electrical safety must be called – attempting to fix it yourself can be life-threatening.
Rust-Coloured, Cloudy, or Foul-Smelling Water
If the colour, clarity, or smell of hot water coming from the tap has changed, it usually indicates changes in the condition of the water heater tank or heating element, not just the plumbing itself.
Rust-coloured water is typically a sign that the tank's internal lining is damaged and the metal has started to corrode – this can also affect the area around the heating element, as corrosion often spreads near the heating element's mounting point.
Water with an egg or sulphur smell mostly results from a chemical reaction between the magnesium anode in the tank and certain bacteria, which is a separate issue in itself but can affect the overall condition of the water heater long-term if not addressed.
- A slight change in smell after a long period of inactivity (e.g., returning from holiday) is normal and usually disappears after a few uses.
- Persistent or worsening rust colour and a constant unpleasant odour indicate a more serious problem in the tank or anode.
How Does This Topic Differ from the Water Heater Cleaning Guide?
If you've previously read our guide on cleaning electric water heaters, you might wonder if this article repeats the same information – it does not. The cleaning guide focuses on how to physically clean the water heater tank and anode and remove limescale during regular maintenance.
This article, however, focuses on how to recognise that something is already wrong – i.e., what symptoms and warning signs indicate that the heating element, electrical part, or tank condition needs checking before you even begin cleaning or repairing. In other words, this is about diagnostics, not the maintenance procedure itself.
Moisture, Water Droplets, or Leak Traces Around the Water Heater
The heating element is attached to the water heater tank via a gasket, which loses elasticity over time and starts to leak. If you notice moisture, a small puddle, or rust streaks on the wall near or under the water heater, it's a fairly sure sign that the heating element's mounting gasket needs checking or replacing.
A small leak may not seem like a big problem initially, but it increases the risk of water reaching the electrical components, which in turn raises the risk of short circuits and electric shock.
- Regularly check the area under and behind the water heater, especially if it's installed in a bathroom or kitchen cabinet.
- Even a small but persistent moisture trace should be inspected – it won't disappear on its own.
- If you notice the RCD tripping at the same time as a leak, immediately disconnect the water heater from the mains power.
Magnesium Anode Wear and Its Effect on the Heating Element
The magnesium anode is a 'sacrificial' metal that protects the inner surface of the water heater tank from corrosion, gradually degrading itself through chemical processes in the water. If the anode is completely worn out and not replaced, corrosion will begin to attack the tank and eventually the heating element's mounting point.
Most manufacturers recommend checking the anode and replacing it if necessary every one to two years, depending on water hardness and water heater usage. In areas with harder water, the anode wears out faster.
How is Anode Wear Related to Heating Element Inspection?
When a service technician opens the water heater to check or replace the anode, it's logical to also have the heating element and its gasket inspected at the same time, as both parts are usually located in the same opening, and their condition directly affects each other – a worn anode means a more aggressive environment in the tank, which also accelerates the wear of the heating element's mounting.
What You Can Safely Check Yourself at Home
Before calling a specialist, it's sensible to make some simple and safe observations that can help describe the problem and, if necessary, speed up the diagnosis.
- Measure how long it takes to get hot water and compare it with previous experience.
- Visually inspect the area under and around the water heater for moisture or rust stains – only visually, without disassembling the unit.
- Listen for unusual crackling or clanking noises during heating.
- Check the water's colour and smell after letting hot water run for a couple of minutes.
- Check the data plate on the water heater casing to find out how old the appliance is and when it was last serviced, if recorded.
What You Must Never Do Yourself – The Competence of Electricians and Plumbers
A water heater's heating element is in direct contact with both water and electricity, which is why several tasks are legally and for safety reasons reserved for appropriately qualified specialists.
- Removing, replacing, or disconnecting the heating element's electrical connections without first disconnecting the unit from the power supply and plumbing system.
- Independently forcing the water heater to restart after repeated RCD tripping without investigating the cause.
- Opening the water heater tank to remove limescale without the necessary experience and tools – incorrect handling can damage gaskets and create new leaks.
- Touching electrical components (thermostat, RCD, junction box) unless the water heater has been demonstrably disconnected from the mains power.
Who Does What – Electrician or Plumber?
Generally, the electrical part of the water heater (thermostat, RCD, wiring) is handled by an electrician or a plumber-installer with appropriate qualifications, while the maintenance of the tank, gaskets, anode, and water connections falls within the plumber's domain. Many experienced heating system specialists, including ToruFix OÜ, handle both aspects simultaneously, which simplifies the process for the customer.
Summary Checklist – When to Call a Specialist?
If you notice any of the following signs, it's wise to book a water heater inspection rather than waiting for the problem to resolve itself.
- Water heats up significantly slower than before.
- Electricity bill has increased without changes in consumption habits.
- Water heater makes loud crackling, rattling, or clanking noises during heating.
- The Residual Current Device (RCD) repeatedly trips when using the water heater.
- Water is rust-coloured, cloudy, or has an unpleasant smell.
- There is moisture, water droplets, or rust marks on the wall around the water heater.
- The anode has not been checked or replaced in the last two years.
- The water heater is over ten years old and has never had a full inspection.
The Effect of Water Hardness on Heating Elements in Tallinn and Harjumaa
Water hardness levels vary considerably across Estonia, and this directly affects how quickly limescale accumulates on the heating element. In areas with harder water, the limescale layer can thicken significantly faster than in areas with softer water, leading to a more frequent need for inspection.
If you live in an area known for harder water, it's worth monitoring your water heater's condition a little more carefully and not waiting until symptoms become very clear – preventive inspection is cheaper than later heating element replacement.
Information about water hardness can be obtained from your local water utility, and some home test kits allow you to assess the hardness level yourself, which helps determine how often to inspect your water heater.
Are Heating Element Problems Similar for All Water Heater Types?
Different water heater types – standard electric water heaters with a dry heating element, immersion water heaters with a wet heating element, and combined water heaters that also use a heat exchanger – behave slightly differently when it comes to heating element problems.
- In a wet heating element water heater, the element is in direct contact with water, so limescale accumulates directly on the element's surface and quickly affects heating speed.
- In a dry heating element (with the element located in a tube) water heater, the heating element is protected by a metal sleeve, so direct contact with limescale is less, but the risk of overheating increases if the sleeve itself becomes covered with a thick layer of limescale.
- In combined water heaters, where heating also comes from a heat exchanger, heating element problems can be harder to notice, as the water is partially heated from another source – in this case, it's worth monitoring changes in electricity consumption.
Common Misconceptions When Interpreting Heating Element Signs
Many homeowners and apartment owners assume that if the water heater works at all and provides hot water, everything is fine. This isn't always true, as the heating element can operate at significantly lower efficiency without a visible complete failure.
Another common misconception is that if the water isn't visibly dirty or rust-coloured, there can't be a problem with the heating element. In reality, crackling noises, slow heating, and a higher electricity bill can all occur without visible changes in water quality, as these are primarily related to limescale, not corrosion.
It's also mistakenly believed that an RCD tripping is a random power outage and unrelated to the water heater – in fact, such an incident should always be checked separately, especially if it recurs specifically during water heater use.
How Often Should Checks Be Done, Considering Water Heater Age?
The age of the water heater is one of the most important factors influencing how often the heating element and other parts should be checked – a newer unit requires less frequent attention, an older unit more frequent.
- New water heaters (0–3 years) – usually suffice with an annual visual inspection and the manufacturer's recommended service interval.
- Mid-aged water heaters (4–8 years) – an annual check is recommended, including anode condition assessment.
- Older water heaters (over 8 years) – should be thoroughly checked at least once a year, paying special attention to the condition of the heating element, gaskets, and tank corrosion.
How ToruFix OÜ Resolves Water Heater Heating Element Problems?
During a water heater inspection, we check the condition of the heating element, the amount of limescale, anode wear, gasket integrity, and the safety of electrical connections. If necessary, we clean the tank, replace the anode or heating element, and advise on whether to consider a full replacement of the unit.
Operating in Tallinn and Harjumaa, we usually reach the customer quickly, which is especially important in cases where repeated RCD tripping or a visible leak requires immediate intervention.
Impact of Thermostat Setting on Heating Element Load
The water heater thermostat determines the temperature to which the heating element heats the water, and this directly affects the heating element's load and the rate of limescale accumulation. If the thermostat is set too high, for example, above 65–70 degrees, limescale formation accelerates significantly, as higher temperatures promote the settling of calcium compounds on the heating element's surface.
Likewise, incorrect or unstable thermostat operation can cause the heating element to cycle on and off more frequently than usual, increasing mechanical stress and shortening the unit's lifespan in the long run. If you notice the water heater audibly cycling on and off unusually often, it's worth having the thermostat checked.
- For most households, a setting of 55–60 degrees is sufficient, providing enough hot water without excessive limescale and energy consumption.
- Higher temperatures (above 60 degrees) should be used periodically, for example, to combat Legionella bacteria, not permanently.
- If the thermostat does not maintain the set temperature stably and fluctuates strongly, it may indicate a sensor fault.
Is it Worth Replacing the Heating Element or the Entire Water Heater?
If the heating element inspection shows that the problem is only with this one part and the tank, gaskets, and electrical connections are otherwise in good condition, it's usually sensible to replace only the heating element – this is a significantly cheaper solution than replacing the entire unit.
However, if the water heater is already over ten years old, the tank shows signs of corrosion, or there have been recurring leaks, it's wiser to consider replacing the entire unit, as repairing a single part in an old and worn appliance may not be economically viable long-term.
What Factors Influence the Decision?
When making a decision, consider the water heater's age, the general condition of the tank, how often repairs have been made in the past, and whether a newer, more energy-efficient unit would lead to long-term electricity savings. A specialist can provide specific recommendations based on an on-site inspection, taking into account both the current situation and long-term costs.