At Plumbing Immediately, one of the most common questions we get from clients is: “How do I bleed a boiler?” It’s a question that often comes up when heating systems aren’t working as efficiently as they should. In this blog, we’ll explain why this happens, what bleeding a boiler actually does, and how you can do it safely. Plus, we’ll share how our team can help if the problem persists.
Why Do Boilers Need Bleeding?
Boilers and central heating systems work by circulating hot water through radiators and pipes. Over time, air can get trapped in the system, especially in the radiators. This air prevents hot water from circulating properly, causing:
Cold spots in your radiators
Strange gurgling or banging noises
Reduced efficiency and higher energy bills
Many clients don’t realise that trapped air is often the culprit when their heating feels uneven. This is why learning how to bleed a boiler can save you both discomfort and money.
What’s Going Wrong?
When your radiator or boiler isn’t heating properly, it’s usually due to air pockets or low pressure in the system. Here’s what typically happens:
Air enters the system: This can happen after a recent boiler installation, radiator replacement, or system maintenance.
Water circulation is blocked: Trapped air prevents hot water from moving efficiently through the pipes.
Uneven heating and noise: Radiators feel cold at the top, warm at the bottom, or make loud banging sounds.
Many of our clients call us frustrated because they think their boiler is broken, when in reality, bleeding the radiators can fix most of these issues.
Step-by-Step
How to Bleed a Boiler
Before you start, make sure you have:
A radiator key or flat-head screwdriver (depending on your radiator type)
A small container or cloth to catch any water drips
Here’s a simple guide:
Turn off your heating system and let the radiators cool completely.
Locate the bleed valve at the top of your radiator. It usually looks like a small round screw or knob.
Place your container under the valve to catch any water.
Insert the radiator key or screwdriver and slowly turn the valve counterclockwise. You should hear a hissing sound as air escapes.
Close the valve once water starts to flow steadily. This means all trapped air has been released.
Check your boiler pressure and top up if necessary. Your boiler manual will tell you the correct pressure.
This process usually fixes the issue immediately, with radiators heating evenly again.
When to Call a Professional
While bleeding your radiator is a simple task, some issues require expert attention. Call us if:
The problem persists after bleeding
Your boiler pressure drops frequently
You notice leaks or corrosion around valves and pipes
Your system is noisy or inefficient despite bleeding
We at Plumbing Immediately specialise in diagnosing and fixing boiler problems. We can:
Perform a full system check
Re-pressurise and balance your radiators
Replace faulty valves or components
Provide regular maintenance to prevent future issues
Why Choose Us
We’ve helped hundreds of clients with boiler issues across London & Greater London. The friendly, expert engineers make sure your heating system is safe, efficient and reliable. Whether it’s a quick radiator bleed or a full system service, we handle it all with care.
Quick Tips to Keep Your Boiler Healthy
Bleed radiators annually or when you notice cold spots
Check boiler pressure regularly
Schedule routine maintenance with a certified engineer
Don’t ignore unusual noises or leaks
A little attention now can prevent costly repairs later.
Call Us We Operate 24/7 In London
If you’re wondering “how do I bleed a boiler?” or struggling with uneven heating, don’t worry. We offer fast, reliable and professional boiler and heating services. We’ll ensure your home stays warm, safe, and efficient all year round.