At last you can now bleed your radiators without grimy water spitting and spluttering. Trapped air in radiators can affect the performance of your central heating by preventing adequate hot water from entering the radiator. Now you can easily and cleanly expel trapped air and have toasty hot radiators again. Simply place the radiator tool over the bleed valve and unscrew. When water and sludge escape into the clear plastic tube your radiator is free from air, your carpets and walls free from sludge.