Understanding heating issues:

Radiator Cold at Top, Warm at Bottom

Trapped air in radiator:

Cause: Air accumulates at highest point, preventing water circulation

Symptoms: Top section cold, bottom warm, hissing when bleeding

Fix: Professional bleeding removes air, restores full heating

Prevention: Annual bleeding before heating season

Radiator Cold at Bottom, Warm at Top

Sludge buildup blocking water flow:

Cause: Rust, debris, and limescale settled at bottom

Symptoms: Bottom section cold, brown water when bleeding, slow heat-up

Fix: Radiator flush or full system powerflush required

Prevention: Magnetic filter, corrosion inhibitor, regular servicing

Radiator Completely Cold

Multiple possible causes:

• Stuck TRV (thermostatic valve seized closed)
• Closed lockshield valve
• Airlock in system
• Blocked radiator from sludge
• Boiler issues affecting entire system

Requires professional diagnosis to identify specific problem.

Leaking Radiator

Water escaping from radiator:

Common leak points:

• TRV or lockshield valve connections
• Radiator body corrosion (pinhole leaks)
• Blanking plug failures
• Valve spindle leaks
• Pipe connections

Urgent repair needed – leaks damage floors, cause mold, waste heat.

Noisy Radiators

Unusual sounds indicate problems:

• Gurgling – trapped air or low water level
• Banging – water hammer, system imbalance
• Whistling/hissing – partial blockage or air
• Ticking – expansion/contraction (usually harmless)

Noise diagnosis identifies underlying system issues.

Uneven Heating Across Home

Some radiators hot, others cold:

Cause: Unbalanced system – water takes path of least resistance

Symptoms: Radiators nearest boiler very hot, distant ones cold

Fix: System balancing adjusts the flow to each radiator

Professional service ensures even heat distribution.