Cold Radiators in Horsham? DIY Guide to Bleeding & Balancing Your Central Heating

Is one side of your radiator stone cold while the other is piping hot? 

Are your upstairs rooms freezing while downstairs is baking?

Before calling a heating engineer, the solution may be simple: your system likely needs to be bled or balanced.

As your local heating experts, Prime Boiler Care serving the Horsham District and the Adur District, heres our step-by-step guide to tackling this common issue yourself 

Part 1: Bleeding Radiators Releasing Trapped Air.

Air often gets trapped in the highest point of your radiators, stopping hot water circulation and creating cold spots.

Step-by-Step Guide 

Turn Off the Heating.

Crucially, turn off your boiler and allow the radiators to cool down completely; hot water and air are under pressure.

Gather the necessary tools: a radiator key and an old cloth towel.

Locate the Valve.

Find the small square pin screw at the top corner of the radiator opposite the temperature valve.

Slowly Turn the Key.

Insert the key and turn it counter-clockwise very gently.

You will hear a hissing sound as the air escapes.

Stop When Water Appears.

As soon as water starts to spit or dribble out, immediately close the valve by turning the key back clockwise.

Check Pressure.

Once all radiators are bled, check the boiler pressure gauge; it will likely have dropped.

Repressurise your boiler to its correct cold pressure setting, usually 1 bar.

Part 2: Balancing Radiators to Ensure Even Heat.

If your radiators are bled but some heat up much faster than others, typically those closest to the boiler, your system is unbalanced.

Balancing Explained.

Balancing ensures the boiler pump pushes hot water evenly throughout the house.

This is achieved by controlling the flow using the small lockshield valve, which is often hidden under a cap on the opposite side of the main thermostat valve.

Turn Off the Heating.

Cool Down.

As before, turn off the system and let all radiators cool completely.

Open All Valves: Turn both the thermostatic and lockshield valves on every radiator to the fully open position, counter-clockwise.

Turn Heating Back On.

Note the order in which your radiators heat up.

Start with the Hottest Closest.

Turn the heating back off. Once cold, find the radiator that heated up fastest.

Turn the lockshield valve fully closed clockwise, then open it by only a quarter of a turn.

Move to the next repeat, opening the lockshield valve a slightly wider amount, e.g., half a turn on the next-hottest radiator, and so on.

The furthest radiator should be left entirely open.

Need Expert Help.

If your radiators remain cold, the problem may be system sludge, requiring a powerflush, or a faulty diverter valve in your combi boiler.

Prime Boiler Care can quickly diagnose these issues.

 Save yourself the hassle.

For professional radiator balancing, power flushing, or complete heating diagnostics in the Adur District or Horsham District, trust the team at Prime Boiler Care.

Call us today: 01403 814602

Prime Boiler Care

Suite 54, Standby Business Centre,

Foundry Lane, Horsham, West Sussex, RH13 5PX