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Heating engineer · Brussels and Wallonia
The boiler is leaking or dripping
A puddle or a drip under the boiler almost always comes from the water circuit, not the gas. It isn't a life-threatening emergency, but don't leave it: water damages the electrical parts and the pressure eventually drops.
The most common causes
The safety valve
It lets water out when pressure gets too high, often because of the expansion vessel. Water then runs from its small pipe.
A fitting or seal
Under the boiler, a loose fitting or a worn seal drips little by little.
The condensate drain
A condensing boiler produces water. If its pipe or trap is blocked or loose, it overflows.
Inside the boiler
Pump, heat exchanger: an internal leak is more serious and needs an engineer.
What you can check yourself
- Find where the water comes from: the safety valve's small pipe, a fitting under the boiler, or the condensate pipe.
- Check the pressure gauge and note the reading.
- Put a container and a cloth under the leak.
- If water runs onto wires or electrical parts, switch off the boiler's power supply.
Don't
- Opening the casing or tightening parts inside.
- Blocking the safety valve's pipe: it protects the system.
- Letting it run for days.
Call us if…
- The leak continues.
- Water comes from inside the boiler.
- The safety valve runs regularly.
- The pressure drops at the same time.
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
Is a leaking boiler dangerous?
Not in itself: it's water. The risk is water on electrical parts and pressure dropping until the boiler stops. Switch off the boiler's power if water runs onto it. A smell of gas is a different matter: follow our « Smell of gas » page.
My boiler is dripping from the bottom: where from?
Usually the safety valve, a fitting under the boiler or the condensate pipe. A photo of where it drips, sent with the form or on WhatsApp, helps us prepare the repair.
Find out more
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.
