There are different ways of storing water so if it is the case that you are fitted with a boiler and the water in your home is stored in a cylinder, there is every chance that the water will be heated in an indirect fashion. This type of system is configuered so that you will have two hot water systems. There is the Primary Circuit and the Secondary Circuit. For the primary circuit, a pipe will run from the boiler to a heat exchanger that is actually a coil of copper pipe that is fitted inside the hot water cylinder, from which it returns to the boiler. As long as the boiler is running, the hot water will flow continuously around this primary circuit. When the pipes of the heat exchanger warm up, so too does the water in the cylinder, which can then be drawn off from the top of the cylinder to supply the hot taps around the house (the secondary circuit). A qualified Plumber is familiar with all water storage systems. Usually the hot water cylinder can be found sitting in an upstairs airing cupboard,and is constantly fed up with water from the cold-water storage systems in the roof. The primary circuit as its own top-up supply of water from a small tank in the roof which is known as the feed-and-expansion cistern. London Plumbers work on these types of cylinders. The hot water drawing-off pipework for the cylinder carries on to the roof and ends at the cold-water storage cistern, the boiler’s hot feed pipe to the heat exchanger finishes over the feed-and-expansion cistern in the loft. This will let any air or steam from both circuits to escape safely. One of the major advantages of this type of indirect system is the water that runs through the boiler never mixes with the water in the cylinder and is effectively recycling itself time after time. This action means that there will less scale build up and with an inhibitor added can more or less guarantee that the running and maintenance costs will be greatly reduced.