Good Radiators Make Effective Central Heating Systems

Take a modern car as an example. The engine creates the power by burning fuel. The power is then transferred by the wheels and tyres to pull the car forward. In the central heating world, the engine is your boiler and the wheels and tyres are your wall hung radiators. Just like in cars, a well designed and sized radiator is crucial for effective heat transfer from the boiler into the room and as such guarantee an effective and economic performance of your central heating system.

It might come as a surprise that those sleek looking stainless steel radiators offered by most UK plumbing and heating merchants date back more than 150 years. The first radiator was registered as a patent in 1855 by Franz Sangalli, a German engineer. In effect, despite considerable visual differences, the main working structure of the radiator is the same as the ones registered initially by Mr. Sangalli. The radiators are effectively a hollow case made of metal, shaped as a flat box and attached to the wall to maximize radiation of heat into the room.

Most UK made radiators are constructed from sheet metal with brazed fins (normally internal within an outer casing). Using a simple pump (normally located in the boiler or by the hot water cylinder), hot water is circulated through the central heating loop. The hot water is pumped into the radiator and gradually loses its heat to the surrounding atmosphere. As the water cools off it drops and eventually is pumped out via the return valve (normally at the bottom of the radiator). The air surrounding the radiator absorbs the heat from the water within the radiator and rises to the top of the room. Consequently, cooler air is drawn towards the radiator to get heated up. This convection effect is a simple physical phenomenon that keeps our homes warm in the winter.

Radiators, though tried and tested over many years, still suffer from typical problems from time to time. One of the most common problems is the air pockets that develop within them. These small pockets can be a result of tiny bubbles of air creeping into the sealed central heating system through tiny cracks. Professional central heating installers minimise the risk of such cracks by using compression fittings or other solution to ensure the connection points are free from potential cracks.

Another common explanation for these air pockets it that they are the result of a chemical reaction that occurs when copper piping and other metals come in contact with very hot water. Such pockets (normally made of hydrogen) get trapped inside the system and find their way to the top most point of the system. This is why your radiator does not get hot at the top side, as it is filled up with air pockets rather than hot water. As this reduces the efficiency of the radiator and the central heating system as a whole it is recommended to bleed out such air pockets from the system. This can be easily done by using a bleeding key (which can be purchased in all major DIY stores in the UK). The bleeding key fits into a bleeding screw at the top of the radiator that lets the air pockets escape and return the system to good operating mode.

Another common problem affecting radiators is a build up of sludge. Since hot water rubs against iron, copper and other metals within the closed central heating loop, the resulting chemical reaction creates not only gases but also chemical deposits. Such chemical deposits remain in the sealed system and clog the pipes, reducing their performance and effectiveness.

Such corrosion can be addressed and prevented by ensuring that the plumber installing your central heating system adds a chemical corrosion inhibitor into the closed circulation loop. Prior to doing this most plumbers these days go one step further and actually power flush the system to remove any build up and debris that might have accumulated within the pipes. Even new systems may require a power flush to remove debris that has been there as a result of the manufacturing processes of the pipes and the radiators.
About the Author:
Tal Potishman is editor of Heating Central, which publishes information about UK boilers, plumbers, underfloor central heating and solar thermal systems. He specializes in helping save costs and the planet by consulting on high-efficiency central heating.