Central heating can be a very complex system and generally you should call a qualified central heating plumber. Here are a few tips on what to look for if you have any problems with your central heating system.

How to know if air is in the system? The most common area of trapped air is in radiators. This is fairly easy to detect as the air will reduce the amount of heat radiated. With the central heating switched on, feel the top and then the bottom of the radiator - if the top is noticeably cooler than the bottom, there is a good likelihood that there is air in the radiator. In very severe cases, the whole of the radiator may be filled with air so no difference in temperature will be discernible - if the complete radiator is 'cool' when the central heating is switched on, try bleeding the radiator to ensure that the problem is not just air in the system.

creaking pipes? As the water gets hotter, the pipes expand. As the water start to cool down again the pipes contract. If the pipes are tightly fitting in the floor or wall, they will start to creak as they expand or contract.. If you know the location of the noise, try packing some lagging or a piece of felt around the pipes. It may be that the pipes ate sitting so tight, there is no room for movement. Try cutting a notch in the wood to allow for slight movements in the pipes. Make sure there are not two pipes touching. Place lagging or felt between them if possible. If a pipe appears to sag, use a strut of wood across the joist to sit the pipe on, padding with lagging or felt.

Loss of pressure from system? For a system to work properly the water pressure should remain constant. Modern combination boilers are pressurized systems and water will enter the system from the mains cold water supply through a manual filling device, known as a 'filling loop'. Adding water via the filling loop to the system after a drop of pressure will help bring your system to the correct pressure again.