Whether it’s meeting a plumber for a consultation, having a system explained, or doing a DIY job, some plumbing and heating terms can sound like a foreign language! To help you to understand their meaning, this jargon buster tackles a list of the most common terms plumbers are asked to explain.
Air Lock: Where air gets caught in a high point in a hot/cold water system or central heating system. You can get rid of it by venting (releasing air from) radiators.
Ballcock: is a float operated valve that shuts off water levels in cold water storage cisterns in the attic space or in the toilet cistern. <Pic>
Borehole: A well. In other words a hole drilled into the ground, passing the first layer of rock to obtain water for drinking purposes. Must be checked for impurities before use as it may need to be treated. Boreholes in the context of heat pumps (defined below) refer to the holes that are drilled down to access heat (for geothermal systems).
Cistern: A vessel open to the atmosphere used to supply cold water to sanitary fixtures and to the cylinder in the hot press that makes hot water. Usually found in the attic space (see Gravity system), it should be fitted with a lid to prevent contamination. Not to be confused with a toilet cistern which stores water to flush it.
Condensing boilers: High efficiency boilers that extract heat from the flue gases by sending it through a second heat exchanger which reduces the exhaust gas temperature within the flue. The exhaust gas condenses and is drained away through a separate small discharge pipe.
Copper pipes: Pipework used to be copper but due to cost and ease of installation uPVC is now much more commonly used. Unlike uPVC copper will resist rodent attack, e.g. when run under suspended timber floors. It also has a much longer proven track record (long lasting).
Diameter: The bore or size of any pipe in millimeters, e.g. waste pipe from a sink is generally 40mm, sewage pipes 4inch (100mm) while hot and cold water is usually supplied in ½ or ¾ inch (125 or 200mm) diameters depending on the pipe run and other factors.
Dual Element Heater (Immersion): An electric water heater with an upper and lower element for heating water. It is normally an electric element that can heat quantities of water for a bath or just for sink use. It is principally there to act as a back-up or top up to the main boiler or heat pump.
Dual flush: A toilet that gives users the choice of flushing with the maximum amount of water allowed by law (6 litres) or less water.
Dual heating system: Heating from two different heat sources like oil and solid fuel, or gas and solid fuel, etc.
Efficiency: How much energy you need to use (e.g. gas) to get another form of energy (e.g. space heating), expressed as a percentage. When one form of energy is converted into another, especially in the case of fossil fuels, there’s usually some of it that’s wasted (heat is often lost in the process). The higher the efficiency, the better.
Electric shower: A shower that instantaneously heats water. A pump shower combines two separate hot and cold water feeds.
Feed pump: A pump that supplies water to a boiler or a tank.
Fitting: Used to join two pieces of pipe together, e.g a bend to change direction, T-piece to make a connection to a straight length. Other examples include couplings, bushings or elbows.
Flush valve: Releases water from the tank into a toilet bowl when the toilet is flushed and seals the valve shut when the toilet is not being flushed. Often controlled by a push button.
Gravity system: Unpressurised system where water heats and circulates without the use of a circulating pump. In this type of hot and cold water system mains water is pumped to the cistern (see definition) in the roof space and the water is then distributed throughout the house; pressure is generated by gravity. In the case of a cold roof construction the tank needs to be insulated all around (but not under) to prevent freezing.
Grey water: greywater refers to water that goes down the sink, bath or shower. Water from the toilet or bidet is known as brown water or waste water. Greywater can be reused to flush the toilet after it’s been collected and filtered. Rainwater can also be collected in large holding tanks, allowed to settle and if used for general water needs, treated. More common is to use it for flushing toilets and feeding the washing machine only as treatment can be expensive and requires more maintenance.
Heat pump: A unit that operates similarly to a fridge only in reverse, in this case using a very small amount of electricity to extract energy from the ground (known as geothermal) or air to convert into heat. Some can achieve more than 400 per cent efficiencies (for every 1 unit of electricity supplied 4 units of heat are produced), compared to the efficiencies of fossil fuels, which roughly vary from 60 to 95 per cent.
Low temperature radiators: Radiators that emit higher outputs at lower temperatures and are more efficient. Often made from aluminum.
Magnetic filter: A device which fits onto heating systems and collects iron deposits, which helps to prevent build-up of sludge and corrosive materials in radiators and piping. A chemical referred to as an inhibitor, can alternatively be run through the system to the same effect.
Mains water: Water supplied by your local authority; the pressure it comes in at depends on your area and may be enough to provide adequate pressure to the entire house. Much more common is the gravity fed system (see definition) and nowadays, the pressurised system (see definition).
Manhole: An inspection chamber. This is an opening into the ground from which drains can be inspected, rodded or cleaned out; towards and away from a house.
Manifold: A center point where heating and plumbing pipes all run back to and can be controlled. Often found in the hot press. Generally used for underfloor heating applications; other uses are for zoned systems.
Open vented: Whereby water is supplied from open tanks, normally low pressure.
Overflow pipe: A discharge pipe from tanks and cisterns to prevent overfilling of same. As these are only used in case of malfunction the discharge pipe must be located where you can see it (often at the back door).
Potable water: Drinking water, supplied from mains water or from a deep well (borehole).
Pressurised systems: Whereby water is pumped to give better flow rates to plumbing appliances like taps and showers.
Reverse osmosis: Water softener that is pumped under pressure through banks of fine filters and removes most dissolved particles in the water including lead, but not bacteria.
Softener: Water with lime scale is referred to as ‘hard’ and is usually treated to be softened with systems that rely on salt (another option is reverse osmosis). Lime scale build up damages appliances as well as heating and plumbing systems. A water softener system is usually installed between the mains and the house, preferably outdoors and well insulated. Note that the cold water taps in the kitchen sink will be supplied with mains water, even if hard, as it’s best not to drink soft water.
Soil stack: Pipework that connects the sewage pipes (see definition) to the atmosphere, above top window level; this prevents the build-up of gases and smells within the sewage pipes.
Stop valve: A lever you use to cut off water supplies (for servicing purposes). Generally found in the ground outside your gate or under the kitchen sink.
Temperature and pressure release valve: A device fitted to pressurised cylinders which will release water if the system overheats or exceeds recommended working pressure.
Trap: A device or fitting that provides a liquid seal to prevent the emission of sewer gases (smell) without reducing the flow of water going through it.
Thermostat: This controls the temperature of water or heat automatically. It can be fit on the radiator directly (TRV) or can be controlled separately.
Underfloor heating: There are two types. The first is where pipework is run underneath the floor to heat a room using heated water. The second is where electric elements are run for the same purpose (known as trace heating).
UV filter: Water treatment to eliminate bacteria.
Vent: Found on radiators; they are opened during the filling of the heating system and closed when water sprays out/all air has been released. It can release air from plumbing and heating systems.
Wastewater pipes: Sewage pipes and fittings discharge waste water from sanitary appliances such as basins, baths and wcs. They can be either black (not UV light sensitive) or brown (used internally/below ground) and at bends should be fitted with a spy hole for maintenance.