In a wet central heating system, a boiler heats water, which is usually pumped around a circuit of pipes to radiators fitted throughout the house. Each radiator has valves that control the rate at which water flows through it, thus controlling the amount of time the water spends in the radiator and the amount of heat given off. When the water leaves the radiator, it is piped back to the boiler for reheating. Although some heat is lost from the pipes as the water flows around the system, their narrow diameter and the speed of the flow keeps this to a minimum. A well designed system may have several short circuits radiating from the pump, rather than one large, ensuring that the last radiator on the circuit heats up just as efficiently as the first. Woolwich Plumbers know these systems.


Pipework:

The radiator circuits in most modern wet central heating systems are run in standard 15mm copper pipe, while pipes linking the boiler and the pump and the points were the circuit split off will be 22mm or 28mm diameter. Soldered capillary joints are best (apart from connections to boiler, pump and valves), as these are least likely to leak. Plastic pipes have been developed for use in wet central heating systems, but they can’t be connected directly to a boiler, a short length of copper pipe must be used instead. A Woolwich Plumber can work with copper pipes.


Two-Pipe and Single-Pipe Systems:

More modern systems have a two-pipe layout, were hot water is carried from the pump to the inlet valve of each radiator by a flow pipe, which terminates at the last radiator on the circuit. A second pipe, the return pipe, collects the cooled water from the radiators and carries it back to the boiler for reheating. In the older single pipe layout, the hot water passes through one radiator, then is returned to the floor pipe to be carried on to the next and so on around the circuit, losing some of its heat each time. Consequently, radiators towards the end of the circuit have to be bigger in order to give off the same amount of heat.