water heater


    – Water heater problems: common cases

    – Descaling a water heater in seven steps

Usually, a water heater causes few problems. Apart from regular maintenance, you don’t have to worry about it, but there is always the possibility of a breakdown or malfunction.

You can fix the problem yourself in some cases, but it is advisable to call a plumber or heating engineer to repair the water heater. 

Water heater problems: common cases

Water Heater Repair

The most common water heater problems are:

    – the pilot light goes out, and it is difficult or impossible to turn it back on

    – there is no more hot water,

    – the water is not hot enough,

    – the water smells bad,

    – the water is dirty,

    – the water is red.

Water heater problem: solution table

If you have no hot water, don’t panic. Here are the solutions to consider for this type of problem:

Water heater problem


Possible solutions

For which type of water heater (electric: E and gas: G)?

The pilot light goes out and it is difficult or impossible to relight it.

Thermocouple to be cleaned or changed.


No hot water.

Check that the thermostat terminals are tight.


Mount thermostat to turn on the water heater.


Check fuses/circuit breaker.


Turn on the forced air supply (peak hour) and wait a few hours without drawing water.


Check that power is flowing through the thermostat.


Check that the contactor is properly connected.


Check resistance, anode.


Check the sensor: possible scale.


Drain and descale your water heater if necessary.


Water not hot enough

Check the temperature in the morning or after a complete heating cycle without drawing water, it should be 60/70°C.


  • Turn on the water heater in forced operation (peak hours) and wait a few hours.

  • Check the hot water inlet pipe, it should be cold, but if it is warm for about 50 cm, there may be a leak in the circuit. If the water is hotter in forced operation than in off-peak, there may be a problem with the contactor.


  • Check that there is no cold-water return problem in the hot water circuit, change the safety group if necessary.

  • Clean the heating element and if necessary descale the tank.


Smelly water

Sedimentation problem (possibility of bacteria)

  • Increase the temperature of your thermostat to 65/70°C.
  • If necessary, drain and clean the tank.
  • You can add a bleach tablet.


  • In the presence of sulfate, there is a reaction with the magnesium anode, rotten egg smell.

  • Treat the water or change the anode to a different metal if possible.


Dirty water

Drain and clean the tank.



  • Possible corrosion of the tank.

  • Drain the appliance and check its condition, change it if necessary or, if it is not too corroded, change the anode.


The maintenance of the water heater is done in two steps:

– descaling the water heater,
– Draining the water heater: for your electric or gas storage appliances in order to limit scaling and noise in your tank.

Descaling your water heater: safety and longevity

The annual maintenance of your gas water heater by a professional is mandatory.

Descaling the water heater:

– allows you to maintain the heating body of your gas instantaneous water heater in good working order by limiting the formation of scale,
– ensures the safety of your installation while avoiding over-consumption or breakdown.

The cleaning of the heating body of your gas water heater is part of the annual maintenance to be carried out.
It is strongly recommended that you take out a maintenance contract with a heating engineer as it is compulsory to have your installation checked every year by an authorized professional.

Descaling the water heater in seven steps

Be careful, if you descale your water heater yourself, the operation must be carried out with great care.

Descaling the water heater: before you start

If you want to descale your water heater yourself, here are some recommendations:
– Be careful not to pierce the coil,
– the use of acid is dangerous: wear suitable clothing and protection (goggles, acid-resistant gloves),
– Keep children and pets away,
– Turn off the cold water supply, turn off the gas before working.

Descaling the water heater: the steps

Here is how to descale your water heater in seven steps:


What to do


– Dismantle the heating element according to the manufacturer’s instructions.
– Place it in a plastic container.


– Use either a commercial descaler or 5% hydrochloric acid.
– Always pour the acid into the water and not the other way round to avoid splashing.
– Pour the descaler into the coil via a funnel until the system is completely filled.


Leave the product to work for about 30 minutes.


Rinse the system several times with water to neutralize the acid or descaler.


Reassemble the heating element in the same way.


Turn on the gas, open the cold water supply and light the pilot.


Run a few liters of hot water from the tap.

And that’s it! Now it’s your turn! And, remember to share your experience below.


Read more:

How to Maintain Your Water Heater

How to Descale a Water Heater

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