A glossary of plumbing terms

Access cover.
A point where access can be gained for internal inspection of a drain.

Air gap.
A distance maintainable at the top of an appliance, such as a single basin, at which the water would spill over onto the floor to the underside of the tap Outlet. An air gap is maintained to prevent back siphonage of water from the appliance into the supply pipe.

Back boiler.
The term generally given to a boiler that has been installed within the fire opening in the living room or lounge. A Lee Plumber can work on a back boiler.

Back Siphonage.

Water that is sucked back into the pipework, causing water contamination.
Balancing.

The term used to indicate that the throttling down of the flow of water to certain radiators to force the water to flow to those further away from the pump, thereby allowing them to receive some of the hot water. A Grove Park Plumber can balance a system.
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.

A special spanner designed to reach the nuts located up behind the backs and sinks where there is restricted room to turn a normal spanner.
Boiler.

The appliance that is used to warm up water for washing and central heating purposes.
Bonding.

A system where specific metal pipework is connected either together or to the main earth terminal in order to combat the potential of an electric shock arising from a faulty electrical installation.
Combination boiler.

A design of boiler that is used for the central heating and as a unit to instantaneously heat water going to hot water outlets. It does away with the need to have a hot water storage cylinder.
Compression joint.

A fitting used to join pipes together. It incorporates a compression ring that is clamped onto the pipe and forced up hard against the body of the fitting.
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