Remember that you have a local plumbing professional who is there to help.The central heating systems that we have installed today can choose from one of two circulating pumps for pumping the water around the homes system of radiators.The first is called the fixed head pump and the second is called the variable headed pump. The first pump (fixed head) runs at a constant speed, and so pumps the hot water around the system at a constant rate. The second is different:The speed of variable headed pump can be adjusted. Upon installation of a variable headed pump the engineer will balance the radiators, and alter the pump speed to find the most effective temperature for each room. A Chislehurst Plumber can fit both types of central heating pumps.Sometimes, the temperature of a room cannot be changed by operating the radiator’s valves, however, it can be altered by changing the speed at which the circulating pump is running. Before making this adjustment on the pump, you must confirm that all the radiators are showing the same temperature drop. To do this you will need a couple of clip on thermometers which can be bought from a plumbing retailer. Clip one of these thermometers to the feed pipe just below the radiator valve and the other one to the return pipe, also below its valve. There is a need for a temperature differential of around 11C (or 20F). If this is not achieved, close the lock-shield valve on the radiator very slightly and increase the difference in temperature or you can open the valve to lower. Once the balance is right, you can adjust the pump’s speed slowly in small turns or increments until the best temperature of the radiators is achieved.Note: The pump must be off before making the adjustments.Any problems or questions, you should contact a professional plumbing service like Chislehurst Plumbers who have the relevant skills to carry out all plumbing work.