Basic Radiator Problem Solving

Identification

The simplest way to identify a problem with your radiator is to touch it and find out where it is heating up, and where it isn’t. This touch test narrows down your diagnosis considerably.

Cold at the top

Indicative of one of the most common radiator faults, this normally means trapped air in the radiator, preventing it from filling up with hot water. It’s a simple fault to fix: all you need to do is bleed the radiator. Switch off your central heating system and allow the radiator to go cold. Open the bleed valve (a square peg, usually at one of the top corners of the radiator unit) using a radiator key, or flat-head screwdriver. You’ll hear a hiss of escaping trapped air. This is followed by a trickle of water, which is your cue to tighten the valve again. Turn your central heating back on and you should have a hot radiator all the way to the top.

Cold at the bottom, or in the middle

This indicates poor water flow, most commonly caused by a build-up of sludge in the system, or interior corrosion of the radiator unit or connecting pipes. The best solution is to powerflush the system, which involves removing the radiator unit from the wall and using a machine to flush it out. Where corrosion is the problem, a replacement unit may be required.

Cold all over

Aside from technical oversights (are all your valves switched to the ‘ON’ position?), and mechanical glitches (has the thermostatic radiator valve developed a fault?), the most common cause of a cold radiator is, once again, sludge build-up or internal corrosion. If your radiator unit has corroded and requires replacement, UK Radiators offer an extensive range of competitively-priced designer radiators in a number of sizes, styles and colours, all including free next-day delivery across mainland UK when ordered before 1pm.