There are over 16 million central heating gas fired boilers and over 1 million oil fired boilers installed in the UK. All these boilers and the heating system have to be serviced and maintained. Breakdowns and system faults have to be corrected. Replacement boilers, pumps, controls, radiators etc are needed and upgrades are required in many instances to bring ALL the central heating system in line with approved document Part L of Building Regulations. Other than for the simplest of tasks (and in many cases for that as well!), always use a suitably qualified professional 'Plumber.' CORGI (Gas) or OFTEC (Oil) registered and holding the required qualification of Part L. Demand to see proof of registration. The value of your property depends on it!