There is every chance that at some point in the life of your central heating system, when you are least expecting it will develop a problem of fail completely. The usual suspect is a blockage in the pipework of some description.Symptoms: Some of your radiators are hot and some cold. The Cure:The only way to sort this problem is to carry out a drain of the whole system, if you have the confidence to do the job, then, try it yourself. If you have any doubts you should always call a professional tradesman like a Chislehurst Plumber who is skilled and can do the job. The Process:A). First, isolate the power to the boiler. This should also isolate the pump. If it does not, then, find the pump supply and isolate it and confirm with a tester, as sometimes the pump can have a permanent live electrical feed.B). Let the water cool down so that it can be drained without scalding someone.C). Isolate the main supply to your expansion vessel, and lay a wooden batten across the top of the tank, whilst tying a cord around the middle lowering it down, and tie up the float valve which will stop the water supply and stop it filling. Place one end of a hose onto the outlet of the drain cock and locate the other end into a drain, either inside or out. D). Open the valve on the drain cock, with a correct size spanner. Chislehurst Plumbers drain systems. Once the water stops running out of the system, start bleeding the radiators. This should drain the last of the water. Repair the problem and then, shut the drain cock and every radiator bleed valve. Take off the wooden batten and cord from the tank in the loft. Re-fill the system carefully.Finally: Carry out a bleed on every radiator from upstairs to downstairs and then lastly bleed the heating pump. Visually check the system for correct operation and the job is complete.