If you’ve noticed water pooling around your boiler every time your heating comes on, you’re not alone. A boiler leaking water when heating is on is a common problem, but that doesn’t make it any less stressful. Not only can it affect your heating system’s efficiency, but if left unchecked, it could lead to serious damage or even a full boiler breakdown.
In this guide, we’ll explain why your boiler might be leaking, what could be causing it, and what steps you can take to fix it safely.
Why Is My Boiler Leaking Water When Heating Is On?
A boiler leaking water when heating is on can happen for several reasons. The most common causes include:
1. Pressure Problems
Boilers are designed to operate at a specific pressure, usually between 1 and 1.5 bar when cold. If the pressure is too high, it can cause water to escape from the system. Often, this shows up as leaks around the pressure relief valve or pipe joints.
2. Faulty Seals or Joints
Over time, the seals inside your boiler or the pipe joints can wear out. When your heating system is running and the boiler heats up, the expansion can cause these old seals to fail, leading to a leak.
3. Corrosion or Rust
Older boilers or boilers in damp areas are prone to corrosion. Rust can eat through metal components or connections, creating a slow but steady leak when the system heats up.
4. Issues With the Heat Exchanger
The heat exchanger is one of the most critical parts of your boiler. If it develops a crack or gets blocked, water can escape whenever the heating cycles on. This is a serious issue and usually requires professional attention.
5. Dripping Valves
Some boilers have safety valves, expansion valves, or drain valves that can start to drip over time. This is often more noticeable when the heating is running, as the system’s pressure increases.
How to Check Your Boiler for Leaks
Before calling a professional, there are a few simple checks you can do:
Inspect Around the Boiler – Look for obvious puddles or damp spots near pipes, valves, or the boiler itself.
Check the Pressure Gauge – If it’s consistently above 2 bar when cold, your boiler may be over-pressurised.
Listen for Drips – Sometimes you can hear the leak even if it’s not pooling yet.
Look for Corrosion – Brown or orange marks on pipes or the boiler body indicate rust and potential weak points.
Important: Never attempt to dismantle the boiler yourself unless you are a qualified gas engineer. Boilers are pressurised and contain hot water that can cause injury.
Can I Fix a Boiler Leaking Water When Heating Is On?
Some minor issues, like topping up the pressure or tightening loose connections, can be managed if you’re confident. However, for most leaks especially if they involve internal seals, the heat exchanger, or corrosion it’s best to call a Gas Safe engineer.
Professional engineers can:
Identify the exact source of the leak
Replace worn seals or faulty valves
Repair or replace damaged heat exchangers
Flush and service the system to prevent future leaks
Trying to patch the problem yourself might only make it worse or void your boiler warranty.
Why You Shouldn’t Ignore a Boiler Leak
A leaking boiler can quickly turn into a bigger problem:
Increased energy bills – A leaking boiler works harder to heat your home.
Damage to your property – Water can ruin floors, walls, and carpets.
Risk of complete boiler failure – Small leaks often signal underlying issues that can lead to expensive repairs.
In short, the sooner you deal with a leak, the safer and more cost-effective it is.
Call a Gas Engineer Today
If you’ve noticed your boiler leaking water when heating is on, don’t wait until it’s too late. A certified Gas Safe engineer can assess the problem, fix it safely, and ensure your boiler is running efficiently.
Whether it’s a minor seal replacement or a full repair, professional help is the quickest way to stop the leak and protect your home.
Pro Tip: Regular boiler servicing can prevent leaks before they happen, saving you money and stress in the long run.
Get Your Boiler Fixed Today, Call a Gas Safe Engineer
Don’t let a leaking boiler disrupt your home or damage your property. Our certified Gas Safe engineers can quickly identify the problem and fix it safely, ensuring your heating is reliable, efficient, and worry-free. Contact us now to book a service.