Our central heating system is actually referred to as a wet central heating system hot water flows through all the pipework of the system including the radiators. The main driver of this kind of system is the boiler that burns fuel, or maybe it uses a heat exchanger that transfers the heat to the water which is feeding the network of pipes. Wet systems are probably the most popular way of running a heating system in the United Kingdom. Every radiator has valves which control the rate of flow, and so controls the time the water is in the radiator and the amount of heat. Well designed systems can have several short circuits radiating from the pump, rather than one large, ensuring that the last radiator in the chain heats just as well as the first. Croydon Plumbers know these systems.Pipework:The radiator circuits are run in 15mm copper pipework, while pipes linking the boiler and the pump and the points were the circuit splits off are 22mm or 28mm in size. Capillary joints with solder are best (apart from connections to boiler, pump and valves), and are least likely to leak. Plastic pipework has been developed for use in wet central heating systems, but can’t connect to the boiler, using a short length of copper pipe instead. A Croydon Plumber can fit copper pipework.Two-Pipe and Single-Pipe Systems:Modern systems use something called a two-pipe system. This system is where the generated hot water is circulated from the pump to the inlet valve on every radiator in a flow pipe, that stops at the last radiator in the system. A secondary pipe, called the return pipe, takes the cool water from the radiators back to the boiler to be re-heated. Note:There is an older single pipe version, where the hot water flows through a single radiator, and then returns to the floor pipe and on to the next and so on round the system, but losing some heat each time. Using this system the radiators near the end need to be bigger to still give out the same heat.