Radiator Not Heating Up
One or more radiators in your home aren't heating up properly, staying cold while others work normally. This is one of the most common heating issues in North London homes.
📋 Routine - Plan AheadCommon Causes
Trapped air in the radiator (most common)
Sludge buildup blocking water flow
Thermostatic valve stuck or faulty
Balance issue in the heating system
Pump pressure too low
Radiator valve closed accidentally
Signs Your Radiator Needs Attention
Radiator cold at the top, warm at bottom (trapped air)
Radiator warm at top, cold at bottom (sludge)
Radiator completely cold (valve or system issue)
Radiator makes gurgling or bubbling noises
Other radiators in the house work fine
Radiator takes much longer to heat up than others
🚨 What Happens If You Ignore This?
A cold radiator means you're paying to heat water that isn't warming your room. Over time, sludge buildup can spread to other radiators and damage your boiler.
How to Diagnose Your Cold Radiator
Check Both Valves Are Open
Locate the valves at each end of the radiator. The thermostatic valve (TRV) should be set to a number, not 0. The lockshield valve (covered with a plastic cap) should be open - turn anticlockwise to open.
Feel Where It's Cold
Carefully feel the radiator when heating is on. Cold at top = air. Cold at bottom = sludge. Cold throughout = valve or system issue.
⚠️ Safety: Radiators can be very hot. Touch carefully.
Check Other Radiators
If all radiators are cold, it's likely a boiler or pump issue. If just one or two, it's radiator-specific.
Listen for Noises
Gurgling suggests trapped air. Banging might indicate water hammer. Silence when expecting heating may mean no flow.
⚠️ Call a Professional If You Notice:
- •Bleeding doesn't solve the problem
- •Multiple radiators are affected
- •You suspect sludge buildup
- •The TRV appears stuck or broken
- •The problem returns repeatedly
- •You're not confident with DIY
Solutions
🔧 DIY Solution
Difficulty: easy
- 1
Turn off your heating and wait 30 minutes for radiators to cool
- 2
Locate the bleed valve at the top corner of the radiator
- 3
Place a cloth underneath to catch water drips
- 4
Use a radiator key (available at hardware stores for ~£1) to turn the valve anticlockwise
- 5
You'll hear a hissing sound as air escapes - this is normal
- 6
Once water starts dripping (no more air), close the valve quickly
- 7
Check your boiler pressure (should be 1-1.5 bar) and top up if needed
- 8
Turn heating back on and check if radiator heats evenly
👷 Professional Solution
If bleeding doesn't work, we'll diagnose and fix the underlying issue - this might involve clearing sludge with a power flush, replacing a stuck TRV, or rebalancing your system.
How to Prevent Cold Radiators
Bleed radiators annually before winter
Add inhibitor to your system (ask during annual boiler service)
Consider a power flush every 5-10 years
Don't let radiators go unused for long periods
Install a magnetic filter (MagnaClean) to catch sludge
Get annual boiler servicing - engineers check system health
Frequently Asked Questions
Find answers to common questions about our services.
Still have questions? We're here to help.
Contact UsStill Having Problems?
If you've tried the DIY solutions and still have issues, or if you'd prefer a professional to handle it from the start, we're here to help.
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