Boiler does not heat water and indicators are not lit: reasons and what to do

Imagine expecting a hot shower to start your day when you wake up on a chilly morning, only to discover that your boiler isn’t heating the water and that its indicators won’t go on. This annoying situation can cause disruptions to your daily schedule and leave you perplexed as to what’s gone wrong. This post will discuss some typical causes for your boiler’s inability to heat water and illuminate its indicators, as well as doable troubleshooting techniques that may help you fix the problem.

Firstly, let"s address the heart of the matter: why isn"t your boiler heating water? There could be several reasons behind this dilemma. One possibility is a malfunctioning thermostat, which regulates the temperature of the water inside the boiler. If the thermostat is faulty or incorrectly set, it may prevent the boiler from heating water to the desired temperature. Additionally, a buildup of limescale or sediment within the boiler"s heating elements can impede its ability to heat water efficiently. In some cases, a malfunctioning diverter valve, which directs hot water to either the central heating system or the taps, could be the culprit.

The absence of indicator lights on your boiler is another important problem that needs to be fixed. These indicator lights act as visual cues, giving important details about the condition of the boiler and any possible problems it might be having. Should the indicators stay dark, there may be an issue with the power supply. It’s possible that a fuse blew or that there was a problem with the boiler’s electrical connection. Alternatively, the indicator lights might not be lighting because of a problem with the boiler’s circuit board or control panel.

After identifying a few possible reasons why your boiler isn’t heating water or producing any indicator lights, let’s talk about how to troubleshoot the problem. First and foremost, make sure the boiler’s power supply is working. Verify that power is reaching it and that the fuse or circuit breaker hasn’t tripped. Try resetting the boiler by turning it off, waiting a few minutes, and then turning it back on again if everything seems to be in working order. Occasionally, a straightforward reset can fix small problems and bring functionality back.

It might be time to examine and clean the various parts if restarting the boiler has no effect. Start by examining and, if required, adjusting the thermostat settings. Next, look for any indications of sediment or limescale buildup on the boiler’s heating elements. If applicable, clean the components gently to increase their effectiveness. Check the diverter valve for any obvious damage or obstructions that might be impeding its functionality as well.

It is advisable to seek professional assistance if, despite your best efforts, the boiler still refuses to heat the water and the indicator lights stay dark. An experienced heating engineer or technician will have the know-how and resources necessary to accurately diagnose the problem and carry out the necessary repairs. Recall that doing a boiler repair on your own can be risky and may nullify any warranties that may be in place. To guarantee the effectiveness and safety of your heating system, it is always best to seek the assistance of qualified professionals.

Issue Possible Causes
Boiler not heating water 1. Thermostat malfunction
2. Pilot light out
3. Gas supply issue
4. Faulty heating element
Indicators not lit 1. Power supply problem
2. Circuit breaker tripped
3. Control panel issue
4. Fuse blown

The water heater does not heat when the elements are faulty

The majority of the time, broken components cause the water heater to stop heating water. The most frequent reason for breakage is:


Specifically due to general wear and tear and prolonged use without maintenance, which causes the tubular heater to break down.


The rod is coated with magnesium and is composed of a non-corrosive stainless steel. Because of the way this device draws salts to itself, the heating element lasts a long time.

Kindly take note! The water heater may stop heating water because of corrosion that forms when the anode breaks from normal wear and tear. The metal rod needs to be changed once a year.


The element that regulates the liquid’s heating to a specific extent. Its duties include measuring the water’s temperature, comparing it to the user’s set point, and turning the relay on or off.

Insulation gaskets

The primary function of the flange connector and the storage tank’s sealing components is to shield the owner from electric shock.

Causes of malfunction

Scale buildup, defective thermal protection, and liquid supply interruption from the safety valve failure are common reasons why the boiler fails to heat the water and fails to illuminate. Hardly ever, a water heater malfunctions because of limestone, a bad electronic module, or operating the unit at full capacity.

Be mindful! A detailed visual inspection of the water heater is required to determine the precise cause of its inability to heat. It is best to leave this to skilled artisans.

Poor water quality

When someone asks why the water heater doesn’t heat the water to the right temperature, the answer is that boilers malfunction most frequently when the water contains heavy metals, hydrogen sulfide, and other chemicals.

Damage to electrical wiring

It’s possible that the equipment malfunctions due to damaged wiring. Verify that all of the wires and cables are secure and undamaged before beginning.

Errors in the installation process

It is imperative that the installation of the boiler be left to skilled artisans. If not, you run the risk of misinstalling it or breaking the boiler’s ceramic surface.

Improper operation of the appliance

It happens frequently that installing a larger capacity water heater or not following the instructions in the device’s technical handbook results in the water heater not heating up. For this reason, before using the appliance, you must read the instructions.

Signs of malfunction

When a water heater is broken, it will either not turn on at all or make strange noises.

Leaks from cables and the appearance of error codes on the dashboard are frequently signs of equipment failure.

Indicator on the panel is lit

When the water heater is not heating the water but there are indicator lights illuminated, the heating element is malfunctioning. It is essential to use a multimeter to adjust the resistance measurement and connection to the heating device in order to verify that the heating element is not malfunctioning. Open circuits and system shorts may cause zero to illuminate and show up on the indicator.

Kindly take note! The automation is triggered, which disconnects the device as soon as it is turned on, which is another sign that the TEN is not functioning. This shows that the electric heater in the tub is burning.

It is simple to identify such a malfunction. When the device is turned off, the thermal protection button is pushed in. Descaling or replacing the heating element is required if the heater is turned on after that.

Because of a malfunctioning anode, a magnesium rod that destroys and prevents scale formation, lime deposits accumulate on the heating element.

The light bulb on the panel is not illuminated

It is essential to use a tester or multimeter to check if the thermostat has a voltage supply if the dashboard light bulb is not glowing. The tester is attached to the boiler for this reason. It is essential to attempt to restart the system’s operation if there is voltage. The thermostat needs to be changed if it displays zero phase or spikes.

The boiler does not heat up to maximum

Many people frequently encounter the issue where the light bulb fails to glow and the boiler fails to heat the water to the maximum volume. In this instance, it could be:

  • The heating element is defective or inoperative;
  • The heating element has deposits in the form of limescale;
  • The safety valve is defective;
  • The electronic board is not working.

It is essential to drain the water heater and disassemble it if you suspect any of the aforementioned issues. Next, use a voltage indicator, tester, and multimeter to examine every component.

The most common cause of the boiler’s inability to reach its maximum heating temperature in the TEN. This issue pertains to boilers that are older. The heating elements’ service life is restricted in them. They work for a maximum of four years. The heating element develops a thick layer of deposits after extended use, which lowers the heat output. An open circuit could cause the element to short circuit. There’s also a chance of burnout. After that, a new heating element will need to be installed. The boiler unit’s incorrect installation and operation are frequently the root cause.

Signs if the light bulb is on but the water does not heat up

If the water doesn’t heat up despite the light being on, you might need to adjust the thermostat or turn the cistern knob to the lowest position. In order to restart the device, turn the knob to the maximum setting in the first scenario and press the thermal protection button in the second.

Ways to solve problems

The best way to fix a non-functioning boiler is to identify the causes of the equipment’s breakdown.

Replacement of the heating element

As per the instructions provided with the equipment, replacing the heating element should be done by a qualified and experienced craftsman or the user themselves. It is important to remember that replacing the heating element on a boiler follows the same procedure even though each boiler has a unique appearance and set of design elements.

You must accept the following job offer:

  • pliers;
  • indicator screwdriver, flat and Phillips screwdriver;
  • wrench set.

Kindly take note! It doesn’t matter what caused the heating element to need to be replaced; you must follow these procedures step-by-step:

  1. Turn off the boiler and shut off the water;
  2. Put the hot water faucet in the closed position;
  3. Drain all the liquid from the heating element;
  4. Remove the cover with an indicator screwdriver and make sure that there are no voltage terminals;
  5. Put the boiler on the floor, unscrew the nuts and disconnect the wires. It is better to photograph the process of disconnecting all the parts, so that all the wires can be reinserted in the same order.
  6. Replace the heating element and put everything back in place, proceeding in reverse order, making sure that no water gets on the contacts.

It is important to remember that, in addition to replacing the tank, the insulation, gaskets, and magnesium anode must frequently be changed if the tank is dented or broken.

Cleaning the heating element

You must take citric acid and support in a water-lemon solution for several days in order to clean the TEN covered in scale. A stiff brush is used to remove dirt and scale residue.

Thermostat replacement

In the event that a new thermostat with a pressure ring needs to be installed, disassemble the water heater, remove the control unit, remove the thermostatic sensors, and remove the pressure ring first.

It is important to remember not to use the water heater right away after changing the thermostat. It is essential to drain the accumulated air, open the hot water tap, and make sure there are no leaks in the connections. A test run with a progressive rise in heating temperature can then be carried out.

The plug is heating up

The heating device’s wattage could be the cause if the plug becomes slightly heated while the boiler is operating. But in extreme heat, the issue might be a shoddy tee fitting or extension. An extension cord with a wide wire cross-section should be used to ensure safe operation.

There are instances when the socket may be the issue. The plug socket loosens after extended and frequent use. As a result, the plug’s temperature rises. It is best to make sure the socket is firmly seated in its socket on a regular basis. The gadget needs to be replaced if the plug comes loose from the socket.

The issue might be a faulty internal wire contact if the plug is the only one that is hot and the cable next to it is only slightly heated. Tightening the terminals in the plug will easily solve the issue. Such a plug needs to be replaced if it isn’t disassembled.

Be aware that the heater connection points, the heating element, or the extension cord’s inadequate wire cross-section can all cause the cord to heat up. Things like this frequently cause the wire to catch fire. It is essential to replace faulty heating elements and insulate the wiring with reliability to prevent fire and explosion.


If it was discovered during diagnostics that the boiler unit receives current, the device must be disconnected from the mains. Next, locate the thermostat thermal protection button and press it until a click sounds. It is possible to replace the magnesium anode if, after a while, the boiler itself starts to function properly and it becomes necessary to remove the scale that has formed and examine the water heater’s internal operation.

If the thermostat breaks down, it’s simple to fix on your own. Since many domestic and foreign boilers use electronic thermostats, it is impossible to perform the repair on many water heaters. Water heaters made by T-Tech and Ariston can be repaired.

It can be quite annoying, particularly in the winter, if your boiler isn’t heating the water and the indicators aren’t coming on. This problem could be caused by a number of factors, from straightforward solutions to more complicated issues.

First, make sure the boiler is receiving power. Occasionally, a blown fuse or a tripped circuit breaker may be the cause. The issue might be resolved by changing the fuse or resetting the breaker.

Examine the thermostat settings after that. Make sure the thermostat is operating properly and is set to the appropriate temperature. The thermostat might require replacement or repair if it is malfunctioning.

A common problem might also be with the pilot light. The boiler will not be able to heat water if the pilot light has gone out. Relighting the pilot light safely requires adhering to the manufacturer’s instructions. It’s best to get in touch with an expert if you feel uneasy or unsure about doing this yourself.

A broken pump or low water pressure can also stop the boiler from heating the water. Examine the boiler’s water pressure gauge; if it isn’t at the suggested level, you might need to top off the system. The pump will require maintenance or replacement if it is malfunctioning.

It is advisable to contact a licensed heating engineer or plumber if none of these fixes work. They’ll be able to correctly identify the issue and suggest the required fixes. Without the necessary skills and knowledge, attempting to fix complicated boiler problems yourself can be risky and could even worsen the situation.

Maintaining and servicing your boiler on a regular basis can help stop these issues from happening later on. Plan yearly boiler inspections with a qualified technician to make sure it’s operating safely and effectively.

You can guarantee a warm and cozy home environment, even in the coldest months, by addressing the root causes of your boiler’s inability to heat water and illuminate indicators.

If your boiler isn"t heating water and the indicators aren"t lighting up, it can be frustrating and chilly. Several reasons could be behind this glitch. Firstly, check if there"s power reaching the boiler – a blown fuse or tripped circuit breaker could be the culprit. Next, examine the thermostat settings; ensure it"s set to heat and at the right temperature. Also, give the boiler a look-over for any visible issues like leaks or blockages. If everything seems fine externally, it might be an internal malfunction, possibly with the heating element or ignition system. In such cases, calling a professional technician is your best bet to diagnose and fix the problem swiftly, ensuring your home stays warm and cozy.

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Sergey Ivanov

I like to help people create comfort and comfort in their homes. I share my experience and knowledge in articles so that you can make the right choice of a heating and insulation system for your home.

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