If you are considering installing a new radiator system or think you wish to add or resite radiator units, then obviously, a little knowledge goes a long way! It saves time and money to know some of the correct procedures and why certain siting decisions are made. This will apply if you engage the services of a plumber or - if you are in the process of undertaking a plumbing training course - decide you want to install a system yourself, once trained and qualified.A first task is to select a radiator with the correct output. It is important to be aware that the radiator outputs listed in the manufacturers brochures are derived from tested outputs obtained under specific test conditions. Therefore, outputs may vary depending on the installation and heating design requirements of the room or rooms under consideration. Calculations will be necessary to accurately size a radiator for the supply of enough heat output to satisfy individual comfort conditions.Locating radiators beneath windows is recommended to reduce cold down drafts. Curtain lengths - which could adversely affect the distribution of heat when closed - should be considered. Siting radiators at the entrances to a property is particularly important to offset cold air entering the building but take note of any reduced accessibility affecting the safety of the occupants, especially the young and infirm.Part of a City & Guilds Plumbing NVQ 6129 Level 2 course for trainee plumbers will deal also with the many problems of corrosion.Corrosion takes place to a greater or lesser extent in all domestic central heating systems. Just how severe it is will depend on many factors including the types of metal in the system, the degree to which air can be drawn into the system and the nature of the supply water. Even the quality of the installation work can have an effect.On completion of the installation the system should be properly flushed and filled in accordance with the British Standard. This will remove flux residues and installation debris, which might promote corrosion and damage within the system. If it is decided to apply a corrosion inhibitor to maximise the working life of the system, it should be applied in accordance with the manufacturers instructions and should be suitable for the particular metals within the system.Additional pointers and installation tips to look out for are :Pressure testing: Radiators should be high pressure tested to perform at a maximum working pressure and temperature.Brackets : deep hanging slots and equidistant lug positions ensure greater stability. Plastic inserts designed to seat the radiator precisely, are essential to minimise expansion and contraction noises.Warranty : A manufacturers warranty of at least 5 years should be obtained. Check that the radiator is date stamped to provide clear date evidence. Some manufacturers rely on paper inserts which need to be retained by the installer.British Standards: Radiators sold in the UK have to conform and have outputs verified to BS EN442, the European standard for radiators. All radiator literature needs to display BS EN442 compliance as this enables specifiers to show compliance with the European construction products directive.Paint: Two coat, powder paint finish is more scratch resistant than traditional paint or resin finishes.. No further painting is required and the finish remains white and does not discolour.