Does My Radiator Need Bleeding?

Got a radiator that’s warm at the bottom but cold at the top? Or maybe you’re hearing gurgling or bubbling sounds when the heating’s on? That’s a classic sign it’s time to bleed your radiator — a quick job that clears trapped air and gets the heat flowing properly again.

How to Tell if a Radiator Needs Bleeding

Here are the most common signs:

Radiator cold at the top, warm at the bottom
Gurgling or bubbling noises when heating’s on
Uneven heating across radiators
Rooms taking longer to warm up
Low boiler pressure or air bubbles in the system

Trapped air is the most likely culprit — and bleeding the radiator is often a simple DIY fix.

How to Bleed a Radiator (Safely)

Turn off your heating and wait for the radiators to cool down.
Grab a radiator key (or a flathead screwdriver if yours has a slot).
Place a cloth or small bowl under the valve (top corner of the radiator).
Turn the key slowly anti-clockwise — you’ll hear a hiss as air escapes.
When water starts flowing steadily, close the valve again.
Check your boiler pressure — if it’s dropped below 1.0 bar, top it up using the filling loop.

Top tip: Start with the radiators furthest from the boiler and work your way in.

Still Cold After Bleeding?

If the radiator’s still cold after bleeding, or if several radiators aren’t working properly, the issue could be deeper:

Sludge or debris in the system
A weak or faulty pump
Airlocks or low pressure that bleeding won’t fix

In that case, it’s best to book a radiator repair or system check. We may recommend a heating system flush if the problem is caused by built-up sludge.

Should You Bleed All Radiators?

If one radiator needs it, chances are others do too. It’s a good idea to check them all — especially before winter hits. We also recommend having your system checked annually as part of regular boiler servicing.

Need a Hand With Radiator Issues?

At Jones Heating, we deal with radiator problems every day — from bleeding and balancing to full replacements. If you’ve got a stubborn radiator or suspect something more serious, we’ll sort it quickly and properly.

📞 Call us: 01383 660098
🌐 Learn more: Radiator Repairs in Dunfermline

Serving homes across Dunfermline, Kirkcaldy, and Fife — with honest advice and fast fixes to keep your heating running smoothly.