Bleed a radiator
Save £50–80 in 15 mins — no heating engineer needed
Most people call a heating engineer for this. You probably don't need to.
Last updated: January 2025
Only basic tools needed — most homes already have them.
Before you start
Do this if your radiator is cold at the top but warm at the bottom — that means trapped air is preventing hot water from circulating.
You need a radiator bleed key (from any hardware shop) and a cloth or small container to catch drips.
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Tools & materials
- !Radiator bleed key— buy from any hardware shop
- ✓Old cloth or small container— to catch drips, any household rag will do
Want everything in one go?
Prices shown on retailer sites. Always check current pricing before purchasing.
Turn off the heating
Switch off your central heating and wait 20–30 minutes for the radiators to cool. Never bleed a hot radiator.
Most people get this done in under 5 minutes.
Where beginners go wrong
Opening the valve too far and letting too much water out, dropping the boiler pressure.
Not placing a cloth under the valve and getting water on the floor.
Forgetting to check boiler pressure afterwards, causing the boiler to cut out.
Stop and call a heating engineer if...
The boiler pressure keeps dropping after you top it up
The water coming out is black or very murky
The radiator is still cold all over after bleeding
Cost breakdown
Recommended starter kit
Five tools that cover most home repairs.
- →Adjustable spannerAmazon·Screwfix
- →Screwdriver setAmazon·Screwfix
- →PTFE tapeAmazon·Screwfix
- →Spirit levelAmazon·Screwfix
- →Tape measureAmazon·Screwfix
Want everything in one go? Get it on Amazon
What you just learned
You now understand how central heating systems circulate water and why air gets trapped. These skills transfer to balancing radiators and maintaining your boiler pressure.
Most people would pay a tradesperson for this.
How long will this actually take me?
First time
15–20 mins
With experience
5 mins
The hardest part is usually finding the bleed key — have it ready before you start.