Electric water heater not heating: causes and what to do
The electric water heater is common for hot water: according to IDAE it is present in 29% of homes. When it stops heating, there is almost always a cause that can be found. This guide explains the most frequent ones and what to check safely.
Reviewed on 5 October 2026. Informational guide: it does not replace a professional assessment or the official text of the rules cited.
Common causes
- Faulty or limescale-covered heating element: it heats less or stops heating.
- A thermostat in poor condition or badly set.
- No power supply: the water heater protection in the fuse box has tripped.
- Limescale in the tank: the water takes longer to heat and runs out sooner.
- A water leak from the tank or the connections.
What to check safely
- Look in the fuse box to see whether the water heater protection has tripped. If it trips again and again, do not insist.
- Check that the selector or thermostat is not set low.
- Look for dripping or damp under the water heater.
- Do not open the electrical cover with the power on: disconnect it first.
What not to do
Do not tamper with the heating element or wiring if you do not know how, and do not keep resetting the protection if it trips again: there may be an earth leak. See our guide on the RCD.
When to call a professional
- The water heater does not heat after the checks above.
- The RCD or breaker trips when you connect it.
- There is a water leak from the tank.
- The water takes very long to heat or runs out quickly, and you want to decide whether to repair or replace it.
Which rules apply
The electrical side is governed by the REBT and thermal installations for hot water in buildings by the RITE.
Send us a photo and your area on WhatsApp: we will advise you and give you a quote. We reply during working hours (Monday to Saturday, 8:00 to 19:00, excluding public holidays).
Frequently asked questions
Can an electric water heater be repaired or is it better to replace it?
If the fault is the heating element or the thermostat it can usually be repaired. If the tank leaks, replacing the water heater is the usual route.
Why does the hot water run out quickly?
It may be limescale in the tank, an element that is not performing, or a water heater too small for the household.
Do you install and repair water heaters?
Yes, we install and repair water heaters.
Sources and rules cited
- IDAE, SECH-SPAHOUSEC project (results report, in Spanish)
- REBT, Royal Decree 842/2002, BOE (in Spanish)
- MITECO: RITE, Regulation on thermal installations in buildings (in Spanish)