Does My Radiator Need Bleeding?
Got a radiator that is cold at the top? Here is a simple guide to fixing it yourself.
Common Signs of Trapped Air
Air bubbles in your central heating system naturally rise to the top of radiators, preventing hot water from circulating fully. Look out for these signs:
❄️ Cold at the Top
The bottom of the radiator is hot, but the top is stone cold.
🔊 Gurgling Noises
You can hear water bubbling or swishing sounds inside the panel.
🌡️ Uneven Heating
Some rooms take much longer to warm up than others.
How to Bleed a Radiator Safely
This is a simple DIY job. You just need a radiator key (or flathead screwdriver) and an old cloth.
Turn Heating Off
Essential! This stops the pump pushing more air into the system while you work.
Protect the Floor
Hold your cloth under the bleed valve at the top corner of the radiator.
Open Valve
Turn the key anti-clockwise slowly. You will hear a hissing sound as air escapes.
Close Quickly
As soon as water appears, tighten the valve. Don't overtighten it.
Check Pressure
Bleeding reduces system pressure. Check your boiler gauge and top up to 1.5 bar if needed.
Top Tip: Start with the radiators downstairs and work your way up to the top floor.
Still Cold After Bleeding?
If you have bled the radiators but they are still not working properly, you might have a deeper issue.
⚠️ Signs of "Sludge"
If your radiator is Cold at the Bottom but hot at the top, bleeding won't help. This is caused by thick black sludge settling in the pipes.
You likely need a Power Flush to clear the blockage.
Other common issues include:
- Stuck TRV Pin: The thermostatic valve might be seized shut.
- Unbalanced System: Hot water isn't reaching the furthest radiators.
- Faulty Pump: Circulation isn't strong enough.
Need a Radiator Repair?
At The Heat Network, we deal with radiator problems every day. From bleeding and balancing to full replacements.
Serving homes across Fife & The Lothians with honest advice and fast fixes.
Call 01383 660098View Radiator Services