Radiator Not Heating
Gas Safe Reg. 980201• Same-day across Bradford, Leeds & Yorkshire
If most of your radiators are warm but one or two are cold — or warm at the top and cold at the bottom — you've usually got air, sludge or a stuck valve. We bleed, balance and power-flush systems across Bradford, Leeds and West Yorkshire every week.
Most likely causes
- 1Air trapped in the radiator (cold at the top — bleed it)
- 2Sludge / magnetite build-up (cold at the bottom — needs flushing)
- 3Thermostatic radiator valve (TRV) pin stuck closed
- 4Imbalanced system — flow not distributed evenly
- 5Frozen valve or seized lockshield
- 6Whole loop blocked due to corrosion
What you can safely check first
If it's cold at the top, use a bleed key on the small valve at the top corner. Hold a cloth underneath, open until water dribbles out steadily, then close. Top boiler pressure back up afterwards.
On the round valve, twist to max. If it doesn't click, the pin underneath is stuck. Pop the head off — you'll see a small pin; tap it gently to free it.
Top hot / bottom cold = sludge. Bottom hot / top cold = air. One radiator stone cold = TRV or valve fault.
- Multiple radiators cold and bleeding doesn't help (sludge — needs power flush)
- Black or rusty water when bleeding (system corrosion)
- Banging, gurgling or kettling noises from the boiler
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