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Heating engineer · Brussels and Wallonia
The hot water tank or water heater isn't heating
The cause depends on the appliance: electric hot water tank, tank heated by the boiler, or gas water heater that heats water as it flows. Start by working out which one you have.
The most common causes
Electric tank: no power
Its breaker has tripped, or it only heats during off-peak hours on a dual-rate meter.
Electric tank: thermostat or element
The safety thermostat has cut out, or the heating element has failed.
Tank heated by the boiler
Hot water setting, tank sensor or the boiler's diverter valve: see « No hot water ».
Gas water heater
Ignition no longer works (on some models it runs on batteries), gas tap closed, or water flow too low.
Limescale
It builds up at the bottom of the tank or in the water heater: less hot water, slower heating.
What you can check yourself
- Electric tank: check its breaker in the fuse box.
- On a dual-rate meter, the tank heats mainly at night: after heavy use, you may need to wait until the next night.
- Gas water heater: replace the batteries if it has them, check the gas tap is open and open the hot tap fully.
- Tank heated by the boiler: check on the boiler that hot water is switched on.
Don't
- Opening the tank's electrical cover to reset the thermostat: there's 230 V inside.
- Blocking the tank's safety valve if it drips while heating: a little is normal.
- Smell gas near the water heater? Follow our « Smell of gas » page.
Call us if…
- The tank's breaker trips again.
- The water stays cold even though power or gas is getting through.
- The safety valve runs constantly, even with the tank cold.
- The gas water heater goes out while water is running.
What does a repair cost?
Call-out and diagnosis: €125 excl. VAT. The repair is extra, and you get its price before we start. We usually come within 24 hours (working days) and let you know 1 hour before we arrive.
This advice applies to most boilers. Every appliance has its quirks: if in doubt, your own manual applies, and we're happy to answer on the phone.
Frequently asked questions
My hot water tank drips from the safety valve: is that normal?
A few drops while heating, yes: the water expands and the safety valve lets a little out. Constant running, even with the tank cold, isn't normal: call us.
Repair or replace an old hot water tank?
It depends on its age and condition. A thermostat or element can be replaced; a leaking tank can't. We tell you after the diagnosis, with the price before we start.
A breakdown, a question? Get in touch.
Call us or message us on WhatsApp. Or leave your number, with a photo of the boiler if you like: we'll call you back.
