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Right Radiators Vital for Good Central Heating


One of the most important parts of your central heating system is the humbe radiator. Although rarely in the limelight, the simple radiator is key to getting the most out of your central heating system.

Imagine your boiler is the engine of your domestic central heating system. The radiators are your wheels which transfer all the energy to the road and pull the vehicle forward.

Radiator design and positioning makes a key difference to the effectiveness and output of a central heating system. Quite often it is the boiler that is the focus when discussing your domestic heating needs. However, the heat that is generated by the boiler has to pass through the radiators (remember the wheels analogy) to ensure it actually radiates out into the living space in the most effective way.

It may be hard to imagine that today’s radiators have their roots in the 19th century. They were first patented by a German engineer in 1855. They are primarily made of a hollow metal box, normally with a flat shape and they are most often attached to the wall. Most UK radiators are made of sheet steel with attached (welded or brazed) fins to emit more heat.  The heating medium, most frequently water, is pumped into the top of the radiator. The hot liquid emits the heat into the room and as it cools off it drops to the bottom of the radiator and eventually out. The air around the radiator heats up and creates a convection effect drawing in colder air to heat up.

The radiator size depands on the size and shape of the room to be heated to ensure the temperature is pleasant. Recommended temperature for the living room is 21c and for bedrooms and the kitchen 18c. A correctly sized radiator will ensure the boiler is not overworked and is used in the most cost effective way.

One of the most common problems with radiators is the accumulation of air pockets is a within the central heating system. Over time air bubbles are seeping through tiny cracks in the system causing air pockets. Other reasons for such air pockets can be a result of chemical reaction that occurs within the closed environment. If such gasses (e.g. Hydrogen) are trapped within the central heating loop, it normally remains at the top of the radiator preventing the water from getting there and using the full area of the radiator for heating. In such case it is recommended to ‘bleed’ the radiator from a bleeding screw at the top of the radiator. Radiators on upper floors tend to have more air pockets locked in them, due to the air’s natural inclination to rise to the upper-most point of the loop. As such, top floor radiators will require more frequent bleeding.

Most boiler manufacturers these days require the heating engineer installing the central heating system to power flush the central heating loop prior to commissioning. This ensures the system is clean from any debris that might have accumulated during the years (for example inner corrosion in older systems). Furthermore, most engineers recommend adding a corrosion inhibitor chemical into the closed loop circulating water, to inhibit production of Hydrogen that would otherwise occur as a result of hot water coming in contact with iron.

Another common problem with radiators is noise which develops over time. The noise, which sounds like metal banging, can be a result of expansion and contraction of the metal due to temperature difference and subsequent rubbing of the radiators and pipes against other metal fixtures. It is hence important o ensure that the mounting of the radiators and the pipe work is robust and tight.

This page has been written with contributions from experienced plumbers from Surrey and plumbing and heating engineers from Ilford. Several of the company's experienced heating engineers from Hertfordshire have worked on similar issues as well as some of our Gas Safe engineers from Holland Park and our Clapham heating engineers.

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