Most houses in the UK have a central heating system. This involves a combination of radiators, boiler and plenty of pipes around your home. These pipes are made of metal and carry water and special additives that help carry the heat around your home to the radiators. These are what keep your room nice and toasty on those cold days we get a lot of here in Liverpool.
Over time, the water and additives corrode metal pipes, joints etc.. around your system and start a build up of sludge in the system. This causes your heating to be a lot less effective than it was. As time goes on, it takes a lot more gas to heat the water and a lot more power to keep your home warm. This causes a huge wastage of energy and costs you money!
As part of regular maintenance, you should have the system power flushed.