Glossary
Adjustable Inlets
Adjustable shower inlet connectors/elbows that allow the shower to be installed on different inlet centres making it easier to install.
Airlock
Section of pipework which, due to its layout, enables a pocket of air to be trapped. This results in zero or very little flow through the pipe.
All-in-one power showers take water from both the hot and cold water gravity supplies. They mix the hot and cold to reach the desired temperature. They produce a more impressive spray force than mixer or electric showers, because an internal pump boosts the water flow. They are ideal for homes with a plentiful supply of stored hot water.
Automatic Air Vent
A mechanical device with an integral float that releases air when the water level drops within it. Normally fitted at the highest point of a plumbing system to release trapped air.
Backflow
A flow in a direction contrary to the intended normal direction of flow.
Back Siphonage
A backflow of water where the downstream end of a pipe or hose enters a W.C. Basin, Bath or Showertray, allowing possible siphonage of contaminated water back into the potable water supply.
Bar
A unit of measurement of water pressure approximately equivalent to a column of water 10m high or 14.5 lbf/in2 or 100 kPa. per bar.
BIR
Built-in rigid - The controls and the showerhead are both built in to the wall. No hose or slide bar, it gives you a stylish minimalist look.
BIV
Built-in variable - The shower control is built in to the wall, creating a smart, clean finish. The shower comes with a showerhead, hose, right-angled hose connector, clamp bracket and slide bar. Some models are available with a soap dish.
B.E.A.B.
British Electrotechnical Approvals Board.
Wall mounted sprays usually installed in multiples.
Body Sprays
See Body Jets.
Bonding Clamp
A metal strap fastened to a pipe or fitting to enable electrical earth bonding.
A valve installed where the body is recessed in the wall.
Cabinet Power Showers
Cavitation
Localised boiling of water below 100°C caused by a reduction in pressure due to flow conditions.
Ceramic Disc Valve
A valve where the functional parts are highly polished ceramic components which slide across and seal against each other to control water flow (and sometimes temperature).
A plumbing fitting designed to allow water flow in one direction only. See Expansion.
Cistern
Means a fixed container for holding water at atmospheric pressure. It is normally fitted with a float operated valve and overflow warning pipe.
A fixed container for holding water at atmospheric pressure usually used for providing a feed to a vented domestic hot water cylinder. It can also be used to provide a vented cold supply to terminal fittings.
Concealed
See Built-in.
Cross flow
The water flow from one side of a hot/cold water mixer to the other, possibly leading to a contamination of the water supply.
Cylinder Flange
A plumbing fitting which can be fitted to a hot water cylinder to provide a dedicated hot water supply to a terminal fitting.
Digital Shower
A shower that uses electronic sensors and mixer valve to control flow and temperature. This allows for increased safety control and extra functionality eg. Remote operation.
Distributing Pipe
Means any pipe (other than a flush pipe or warning pipe) conveying water from a cold water storage cistern.
Double Check Valve
Two check valves in series with a test point between the two. See Expansion.
Double Ended Pump
See Twin Pump.
Double Pole Switch
An electrical switching device in which the continuity of both the mains live and neutral is broken upon the action of the switch giving a contact separation of at least 3mm.
Downstream
In the same direction as flow away from a given point of reference. (With the flow of water from a given point of reference).
Duty Cycle
The recommended operating time of the product expressed as a time 'on' and a time 'off '. A continuously rated pump can be operated non stop.
The water pressure in the pipework to a fitting, whilst flow is taking place.
Eco shower
A Shower that has an economy setting to reduce power consumption or water usage.
E.L.C.B.
Earth Leakage Circuit Breaker. See R.C.D.
Electrical Heating Element
A component used in an instantaneous electric shower to heat the water.
Electric Shower
Electric showers normally take water from the mains cold water supply. They heat the water when you turn the shower on, by passing it over a heating element inside the shower - in a similar way to how a kettle works. When you shower, you don't use up any stored hot water - so electric showers are ideal for families and households where there is a limited supply of hot water. Electric showers are always ready to use, any time of the day or night.
EV
Exposed Valve - The shower control is mounted on the wall, and your shower comes with a showerhead, hose, clamp bracket and slide bar. Some models are available with a soap dish.
When water is heated it expands, if the water is trapped with no provision to take up this expansion excessive pressures will occur. See Pressure Accumulator.
Expansion Pipe
See Vent Pipe.
Expansion Vessel
See Pressure Accumulator.
Fixed Showerhead
An over head fixed height showerhead.
Float Operated Valve
A valve used to control the flow of water into a cistern, the valve being controlled by the level of water in the cistern.
Flow Limiter
See Flow Regulator.
Flow Pressure
See Dynamic Pressure.
A device with moving parts which responds to variable inlet pressures to control flow at a reasonably constant rate. These are subdivided into two types:
a) Fixed - manufactured in a range of predetermined flow rate settings.
b) Variable - manually adjustable to provide different flow rate settings.
Flow Restrictor
A device with no moving parts which restricts flow. Unlike a flow regulator it does not keep a constant flow when the supply pressure varies.
Flow Switch
Electro mechanical device that senses a small flow of water and energises an electrical contact.
Flush Fit
See Built-in.
Free Outlet Flow Rate
Fused Spur
A branch off an electrical ring main to a double pole switched connection box fitted with a fuse to enable the connection of a fixed electrical appliance.
Handset
See Hand Shower.
Handset Holder
See Wall Bracket.
A showerhead attached to a flexible shower hose also termed a shower handset.
Header Tank
See Cold Water Storage Cistern.
Hose Retaining Ring
A device which restrains a shower hose to prevent immersion of the showerhead.
Hot Water Cylinder
Means a cylindrical closed vessel capable of containing water under pressure greater than atmospheric.
Impeller
The internal part of the pump that is driven by the motor, and is used to move the water.
Inlet Pump
See Twin Pump.
Instantaneous Electric Shower
Instantaneous electric showers normally take water from the mains cold water supply. They heat the water when you turn the shower on, by passing it over a heating element inside the shower - in a similar way to how a kettle works. When you shower, you don't use up any stored hot water - so electric showers are ideal for families and households where there is a limited supply of hot water. Electric showers are always ready to use, any time of the day or night.
Instantaneous Pumped Electric Shower
Pumped Electric showers operate from a gravity cold water supply. They heat the water when you turn the shower on, by passing it over a heating element inside the shower - in a similar way to how a kettle works. They produce a more impressive spray force than an electric shower, because an internal pump boosts the water flow. Pumped Electric showers are always ready to use, any time of the day or night.
Instantaneous Gas Water Heater
An appliance which heats water on demand whilst the water is passing through it.
Insulation Resistance
The effectiveness of the electrical insulation between current carrying conductors and earth.
Integral Power Shower
Power showers take water from both the hot and cold water supplies. They mix the hot and cold to reach the desired temperature. They produce a more impressive spray force than mixer or electric showers, because an internal pump boosts the water flow. They are ideal for homes with a plentiful supply of hot water.
Maintained Pressure
See Dynamic Pressure.
Manual Mixing Valve
Mixer showers take water from both hot and cold water supplies. They mix the hot and cold to reach a desired temperature. They generally flow faster than electric showers. You can make the flow more forceful by adding a Mira pump. Manual Mixing valves do not compensate for variations in the temperature or pressure of the incoming water supplies and needs to be adjusted manually. Mixer showers are ideal for homes with a plentiful supply of hot water.
M.C.B.
A Miniature Circuit Breaker is an electrical circuit protection device used as an alternative to rewireable and cartridge type fuses. It trips out when too much current flows in the circuit, typically under fault conditions. Do not confuse with R.C.D.
Mixer Shower
Mixer showers take water from both hot and cold water supplies. They mix the hot and cold to reach a desired temperature. They generally flow faster than electric showers. You can make the flow more forceful by adding a Mira pump. Mixer showers are ideal for homes with a plentiful supply of hot water.
Modulating Instantaneous Gas Water Heater
An instantaneous gas water heater or boiler which is fitted with a gas control mechanism to vary the heat input and produce a relatively stable domestic hot water temperature, often termed fully modulating.
Step modulating: Gas controlled heat being less able to maintain a constant output temperature under varying flow rate conditions.
Multi Point
An instantaneous water heater which can supply water to more than one outlet, but not usually simultaneously.
Negative Head
If the cistern is below the level of the shower head a gravity flow of water will not occur. A pump with special switching can be used to obtain a flow of water.
Non-Return Valve
See Check Valve.
Maximum potential flow rate from mixing valve without shower fittings attached.
Outlet Pump
See Single Pump.
Parking Bracket
See Wall Bracket.
Power Shower
Power showers take water from both the hot and cold water supplies. They mix the hot and cold to reach the desired temperature. They produce a more impressive spray force than mixer or electric showers, because an internal pump boosts the water flow. They are ideal for homes with a plentiful supply of hot water.
A pressure vessel inside which is fitted a bladder to accommodate thermal expansion of water or alternatively to absorb the pressure shock waves of water hammer.
Pressure Balancing Mixing Valve
A pressure balancing compensatory shower mixer valve designed to maintain a constant shower temperature under variable inlet pressures but maintained inlet temperatures.
Pressure Compensating
See Pressure Balancing Mixing Valve.
Pressure Relief Device
Safety device fitted to prevent excessive pressure building up within an electric shower heater.
Pressure Relief Valve
Spring loaded relief valve fitted to cold supply on unvented systems to relieve excess pressure safely to atmosphere.
A sudden increase in pressure due to a water appliance being turned off quickly.
Pump Hose
A flexible pipe that connects the pump to rigid pipework.
Pumped Electric Shower
Pumped Electric showers operate from a gravity cold water supply. They heat the water when you turn the shower on, by passing it over a heating element inside the shower - in a similar way to how a kettle works. They produce a more impressive spray force than an electric shower, because an internal pump boosts the water flow. Pumped Electric showers are always ready to use, any time of the day or night.
R.A.C.
R.C.C.B.
Residual Current Circuit Breaker. See R.C.D.
A Residual Current Device measures the electrical current on the outgoing live and return neutral conductors. If any current imbalance exceeds the set trip value it turns off the power supply. Do not confuse with M.C.B.
Recessed
See Built-in.
Right Angle Connector
Riser Rail
See Wall Bar.
Running Pressure
See Dynamic Pressure.
Servicing Valve
A valve for shutting off the flow of water in a pipe connected to a water fitting to facilitate the maintenance or servicing of that fitting.
Showerhead
Any device designed to produce a spray pattern.
Shower Hose
A flexible pipe that connects between the showerhead and the shower control.
Showering Station
See Wall Bracket.
Single Ended Pump
See Single Pump.
Single Outlet Pump
See Single Pump.
A pump used for drawing water from a mixing valve for delivery to a shower.
Slide Bar
See Wall Bar.
Solenoid Valve
An electrically operated valve giving either no flow or full flow.
Strainer
A screen to prevent debris from entering a water fitting.
The water pressure existing at a fitting when no flow is taking place.
Standing Pressure
See Static Pressure.
Supply Pipe
A pipe conveying mains cold water around the building.
Supply Stop Valve
A valve used to isolate the mains cold water supply within a building.
Temperature and Pressure Relief Valve
A Relief valve fitted to unvented cylinders to vent excessively hot water and to relieve excess pressure safely to atmosphere.
Thermal Storage Hot Water System
A hot water system where cold mains pressure water is heated (instantaneously) as it passes through a heat exchanger surrounded by a stored volume of hot water.
Thermostatic Mixing Valve
A device which mixes hot and cold water and compensates for variations in the temperature and, or pressure of the incoming water supplies, to maintain a selected blend temperature.
Transformer
An Electrical device for converting mains voltage to low voltage.
Twin Ended Pump
See Twin Pump.
Twin Impeller Pump
See Twin Pump.
A pump with two independent inputs and outputs typically used for boosting both hot and cold supplies to a shower mixer and/or other terminal fittings (Two pumps can be used in place of a twin pump).
Unvented Domestic Hot Water Cylinder
A plumbing system where the cold feed is taken directly from the mains to provide a high pressure hot water supply. There is no open vent to atmosphere.
Upstream
In the opposite direction to flow towards a given point of reference (Against the flow of water from a given point of reference).
Vent Pipe
An uninterrupted safety pipe which allows air or expansion of water within a hot water system to escape to atmosphere.
A vertical rail assembly to allow height adjustment of a showerhead.
Fixed device for holding the showerhead.
Wall Elbow
Wall mounted device to enable a flexible shower hose to be connected to concealed pipework.
Warning Pipe
An overflow pipe positioned so that its outlet is in a conspicuous position so that the discharge can be readily seen.
Water Fittings
Includes pipes, taps, ferrules, valves, cisterns, mixing valves and similar apparatus used in connection with the supply of water within a building.
Water Hammer
See Pulse Pressure.
Water Jacketed Tube Heater
