The effect of Air In Boiler Systems And How To Bleed Radiators

Trapped air within the boiler system is one of the most common issues affecting its performance. These air pockets can lead to uneven heating, strange noises, increased energy consumption, and potential damage to boiler components over time. Therefore, understanding how air enters the system, its impact on efficiency, and how to remove it by bleeding your radiators can help you maintain a reliable and cost-effective heating solution.

At Maintracts Services Ltd, we have been providing expert plumbing and heating services since 1974. Today, we share this guide to help you bleed a radiator and improve the efficiency of your heating system.

Call us on 02086822244 or email us at info@maintracts.co.uk to book an appointment with our specialists or for hassle-free, in-person assistance!

The effect Of Air In Boiler Systems

Air naturally enters boiler systems over time, and while a small amount is normal, excessive air can cause problems. Let’s explore how air enters the system and its impact on boiler efficiency.

How And When Does Air Enter Your Boiler System?

Air can enter your heating system in several ways, including:

• During system installation or repairs – When a new combi boiler or radiator is installed, air can get trapped inside the pipes.
• Through leaks in pipes or joints – Small leaks allow air to accumulate, especially in older systems.
• Pump suction issues – If the pump draws in air instead of water, it will circulate throughout the system.
• Water refill process – When refilling after draining, air can become trapped, requiring air release valve adjustments.
• Dissolved air in water – The water naturally contains dissolved gases released over time.

Common Issues Caused By Air In Boiler Systems

When air builds up in boiler systems, it leads to several heating issues:

• Cold Spots in radiators – Trapped air prevents hot water from fully circulating, leading to uneven heating.
• Gurgling or banging noises – Air bubbles in pipes and radiators cause disruptive sounds.
• Reduced efficiency – Air blockages make the boiler work harder, increasing energy consumption.
• Potential corrosion – Excessive air exposure can lead to oxidation, causing rust and damage inside the system.
• Boiler pressure drop – Trapped air affects the pressure balance, leading to poor performance.

To avoid these issues, it is crucial to bleed your radiator systems regularly and ensure proper radiator maintenance.

How To Bleed A Radiator: A Step-By-Step Guide

Regularly removing air from radiators is essential to maintaining boiler safety and efficiency. To bleed a radiator system correctly, follow these simple steps.

What You Will Need

• Radiator bleed key (or a flathead screwdriver for some models)
• Cloth or towel (to catch any water drips)
• Small container (optional to collect water)
• Gloves (optional, for safety)

Step 1: Turn Off Your Heating System

Before bleeding the radiator valves, turn off the boiler and allow it to cool. This ensures safety and prevents scalding.

Step 2: Locate The Bleed Valve

Each radiator has a bleed valve, usually found at the top corner. It looks like a small square or slotted screw.

Step 3: Place A Cloth Under The Valve

Position a cloth or small container under the bleed radiator system valve to catch escaping water.

Step 4: Open The Bleed Valve

Insert the radiator key (or screwdriver) into the valve and turn it slowly counterclockwise (about a quarter turn). A hissing sound will indicate that trapped air is escaping.

Step 5: Wait Until Water Comes Out

Keep the valve open until you see a steady stream of water (without air bubbles). Then, quickly close the valve by turning it clockwise.

Step 6: Check Boiler Pressure

After removing air from the radiators, check the boiler pressure gauge. If it has dropped below 1 bar, you may need to top up the boiler pressure using the filling loop.

Step 7: Turn On The Heating And Test

Switch the heating back on and check if the radiators are warming up evenly. If some radiators still have cold spots, repeat the process.

When To Bleed Radiators?

Knowing when to bleed radiators ensures optimal performance. Here are some signs that indicate it’s time:

• Radiators feel cold at the top but warm at the bottom.
• You hear gurgling or bubbling noises.
• The boiler is working harder than usual.
• Your energy bills are increasing unexpectedly.

For best results, bleed a radiator at least once a year, especially before winter, to ensure your home stays warm and energy-efficient.

Common Mistakes To Avoid When Bleeding Radiators

Although bleeding radiator valves is a simple process, homeowners sometimes make mistakes that lead to further heating issues. Avoid these common errors:

• Not turning off the heating – This can lead to hot water spraying out.
• Opening the bleed valve too much – Water may gush out uncontrollably.
• Forgetting to check boiler pressure – A boiler pressure drop can prevent the system from functioning properly.
• Not catching excess water – Can damage flooring or carpets.

By following the correct procedure, you can keep your boiler systems running efficiently and prevent costly radiator repair.

When To Call A Professional

You may need radiator service or boiler replacement if you’ve bled your radiators and still experience cold spots, loud noises, or pressure issues. Here are some cases where you should call an expert:

• The boiler pressure keeps dropping despite refilling.
• Radiators remain cold even after bleeding.
• Leaking or damaged bleed valves.
• Loud banging or kettling noises in the boiler (which could indicate a boiler airlock).

Maintracts Services Ltd – Trustworthy Experts For Radiator Maintenance And Servicing

Excessive air in boiler systems can cause heating issues, reduce boiler efficiency, and increase energy costs. Regularly bleeding radiator valves ensure a cost-effective, energy-efficient, and safe home.

While bleeding radiator systems is a simple DIY task, persistent problems may require professional assistance. If you need expert help with boiler safety, radiator maintenance, or heating system maintenance, Maintracts Services Ltd is here for you!

1. 50 Years of experience – Established in 1974, we have provided expert heating and plumbing services for over five decades.
2. Certified & accredited engineers – Our team is fully qualified and accredited by top industry bodies:

• Gas Safe Registered (for safe and legal gas work)
• NAPIT Approved (for electrical safety compliance)
• CIPHE Membership (Chartered Institute of Plumbing and Heating Engineering)
• APHCC Accreditation (Association of Plumbing and Heating Contractors)

3. 24/7 emergency services – We offer round-the-clock emergency call-outs across London, so you’re never left in the cold.
4. Expertise in all heating systems – Whether you have a combi boiler, conventional boiler, or system boiler, we work with all makes and models, including Worcester Bosch, Vaillant, Ideal, Baxi, Glow-worm, and more.
5. Comprehensive heating services – Our team specialises in:

• Boiler repair and replacement
• Boiler servicing and installation
• Central heating system maintenance
• Thermal imaging for leak detection
• Gas safety inspections for landlords

6. High customer satisfaction – With hundreds of 5-star reviews, we are known for our reliable, efficient, and honest service.
7. Local and trusted – Based in London, we provide fast response times and personalised service tailored to your home or business.

Contact us today on 02086822244, email us at info@maintracts.co.uk, or book an appointment online to keep your boiler systems running smoothly all year round.