Combi boiler.Used for the central heating systems to instantaneously produce hot water outlets. This type does not require a hot water storage cylinder.Compression joint.This fitting is often employed to connect pipes. It is made up of a compression ring that is put onto a pipe and forced against the body of the fitting, forming a joint.Balance.The word balance is used to describe the process of arranging the flow of water to all radiators in a circuit so that none of them become too hot or too cold and all remain balanced in heat. A Bethnal Green Plumber can balance a system.Back boiler.A name for a boiler that has been fitted in the rear of a gas fire opening in a living room or lounge. Back Siphonage.A process by which water is dragged back into a system by suction, causing it to become contaminated.Access cover.Used to gain entry to an important valve to allow visual inspection. Air gap. A gap kept at the top of an appliances, such as single basins, where the water would overflow onto the floor. An air gap is kept to prevent back siphonage of water from the appliance into the supply pipe.Air separator.Also referred to as a de-aerator, this device is sometimes found in a fully pumped central heating system to maintain the neutral point, where the cold feed and vent pipes join the system.Basin spanner.Special spanner used to reach the nuts which cannot easily be accessed behind sinks etc. or where there is restricted room to use a spanner.Boiler.Heats the water that supplies all the central heating radiators and taps for washing in a house. Bethnal Green Plumbers install boilers.Earth Bonding.Metal pipework is connected either together to the main earth terminal in the consumer unit to stop the potential of an electric shock from a fault on an electrical appliance.