Hot water cylinder not heating: what to do
When a hot water cylinder stops heating, first check that power is reaching it: its breaker in the fuse box, the socket or switch and, if there is one, the timer. If everything is on and the water stays cold, the cause is usually the heating element or the thermostat. Do not remove the cover: switch the cylinder off at the fuse box and call a technician.
Safety first: water and electricity in one appliance
In Portugal an electric hot water tank is called a termoacumulador, or simply a cilindro, which is worth knowing if you were searching for hot water tank repair. Water and live parts sit side by side in it. Do not take the cover off: the element and the thermostat behind it are connected to the mains. If water is dripping onto plugs, sockets or the cover, or you smell burning, switch off the cylinder breaker at the fuse box first and leave it off until it has been checked.
What you can check before calling
You can do these four checks without tools or opening anything.
The cylinder breaker has tripped
Find the cylinder breaker in the fuse box, the quadro elétrico. It is often labelled cilindro or água quente. If it is down, reset it once. If it drops again straight away, or every time the cylinder starts heating, stop there: current is leaking somewhere, often at the element. We explain in a separate guide what it means when a circuit breaker keeps tripping.
The socket, the switch or the timer
Some cylinders plug into a socket or have their own switch, and some only heat at certain hours on a timer or a time switch. After a power cut the timer can lose its setting. Also check that the temperature knob, where there is one outside, has not been turned right down.
Lukewarm water that runs out fast
If the water comes out hot but runs out halfway through a shower, the usual cause is limescale at the bottom of the tank taking up space, or a cylinder that is now too small for the household. In winter it is normal for it to last a little less, because the cold water mixed in at the shower arrives colder.
Completely cold water with everything on
If everything is on and the water is still cold, the cause is usually inside the cylinder: the element has burnt out or the thermostat no longer tells it to heat. Both can be replaced without changing the tank, but checking them means opening the cover: a job for a technician.
A leaking cylinder
A puddle under the cylinder calls for two things straight away: switch off its breaker at the fuse box and close the valve on the cold water pipe going into the tank. If the leak is at a connection, it can be repaired. If the tank itself is pitted through by corrosion, there is no repair and it has to be replaced.
Cylinder servicing
Many cylinders that stop heating or start leaking have never been serviced. A service clears the limescale and checks the magnesium anode, the part that wears away to protect the tank from corrosion. Anode maintenance is what extends tank life most.
Cylinder or gas water heater: which one do you have
If your water is heated by a gas appliance on the kitchen wall that lights when you open the tap, that is an esquentador, and the right service is water heater repair in Porto.
When to call a technician and how the repair goes
Call when the cylinder breaker drops every time it heats, when the water stays cold with everything on, when water is coming out of the appliance, or when the hot water no longer covers the household. That is what our hot water cylinder repair service is for, in Porto and across Greater Porto, at any hour. It also covers a hot water tank replacement or a new cylinder installation. If you know it as an unvented cylinder, a photo tells us what you have.
You call or send a message
A person answers. We ask for your address, what is happening and, if possible, a photo of the cylinder and its label on WhatsApp to +351 928 286 711.
We agree the visit
On the phone we give you a realistic arrival time and agree how you would like to pay.
We diagnose with the power off
The technician cuts the power, opens the cover and tests the element, thermostat and connections, explaining what they find in plain words.
You get the quote before we start
We tell you what needs doing and what it costs. If a repair is not worth it, we say so and quote for a new cylinder sized for your household. If you rent, the quote is written so you can forward it to your landlord. Nothing goes ahead without your approval.
We repair and test
We replace the part and check that the cylinder heats again without the breaker dropping. If the part has to be ordered, we tell you how long it will take rather than inventing a date.
You keep the invoice
The invoice lists the work and the parts separately. That document is your guarantee and what entitles you to complain if anything fails.
Hot water cylinder questions
How much does a cylinder repair cost?
It depends on the fault, which is why we do not give prices over the phone without seeing the appliance. The quote is free and given on site, before any work.
Is it worth repairing or should I replace the cylinder?
If the fault is in the element, the thermostat or a connection, the part is replaced and the tank stays. A tank pitted through by corrosion is replaced. You decide once you have the quote.
Do you come out at night or at weekends?
Yes. We answer 24 hours a day, every day of the year. No hot water on a Sunday night is exactly the kind of call we take.