Heating Glossary - Useful Radiator Terms

A to Z on wooden blocks
1 April 2024 30 view(s) 13 min read
Heating Glossary - Useful Radiator Terms

Within our corner of the heating industry, there is a lot of terminology that can often be confusing, particularly when trying to decide on which radiator to choose. That's why we've put together a Heating Glossary, giving a brief overview of most of the commonly used terms in the heating industry. Click the letters below to learn more.


A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z



One of the most widespread metals on Earth and a material commonly used to make radiators due to being lightweight, easy to control, as well as its inherent thermal properties.


The name of our bestselling column designer radiator available in 100s of sizes.

Angled Valve

Angled radiator valves connect a radiator or towel rail to the pipework at an angle - usually 90 degrees. Generally used when the pipework comes from below the floorboards. [See also: Valves]



Bar is a metric unit of measurement used for pressure. Radiators will have an optimum (and maximum) level of pressure (Bar) at which they operate.

Bench Seat

A type radiator (typically steel column) that is often accompanied by a wooden seat affixed horizontally to the top. [See also: Ancona Bench Seat].

Blanking Plug

Fitted to an unused inlet on a radiator or heated towel rail, a blanking plug is used to seal and close the opening.

Bleed Key / Vent Key

A small tool specially designed to open a radiator bleed valve during the bleeding process.

Bleed Valve / Airvent

Generally located at the top of a radiator/towel rail, the bleed valve is used to allow air buildup to be released from the radiator.


Bleeding is a term given to the process of expelling air from a radiator. [See also: How to Bleed A Radiator]

Bluetooth Element

An element that can be controlled from your mobile device via Bluetooth.


A highly versatile alloy metal made of copper and zinc which does not rust and can be used on direct systems.


BS-EN442 is a European standard, and as such, it is the legal responsibility of all radiator manufacturers, distributors, wholesalers, and resellers to ensure all hydronic radiators and towel rails conform to this standard.


An abbreviation of ‘British Thermal Units’ and a measurement of thermal energy. Used to determine how much energy is required to heat a particular room.

BTU Calculator

A useful tool to determine the heat requirements of a particular room, or how much thermal energy is required to heat it efficiently. [See: Calculate Your BTU/Heat Output]


Cast Feet

Cast from a single piece of alloy, these load-bearing feet are designed to provide support to a radiator that sits on the floor (as opposed to being wall-mounted).

Cast Iron (Radiators)

An alloy of iron, cast iron is the original radiator material, both robust and incredibly hard-wearing.

CE/UKCA Marking

By placing a CE/UKCA marking on a product, a manufacturer is declaring, on his sole responsibility, conformity with all the legal requirements to achieve said UKCA/CE marking.

Central Heating

A system designed to warm a building, whereby hot water is heated in the building's boiler (central) which is then circulated through pipes and radiators.

Closed System

A central heating system that is closed off from the external supply of water to the home, designed in this way to help prevent water oxidisation.

Column (Multicolumn)

Column radiators are typically made from tubes of steel and tend to carry a traditional style. The number of columns (2, 3, 4 etc), refers to how many tubes deep a radiator is. Column radiators tend to be a very flexible option, offering numerous different sizes. [See also: Ancona]

Combi Boiler

A combi boiler is a type of boiler that can both provide hot water and central heating from within the same compact unit on demand.


A type and style of interior decorating that contains the very latest styles and trends, to help create an updated and modern look.

Convector Radiator

A radiator that is designed to provide heat by convection from fins either attached to the back or situated between the radiator’s panels.

Corner Valve

Provides a 90-degree horizontal connection and is used where the connecting pipework comes from the wall to a connection on the side or underneath the radiator/towel rail. [See also: Valves]

Curved Radiator

Our Ancona® radiators can be curved so that they neatly fit into bay windows or around columns. Check out our Ancona Curved Radiator HERE.


Delta T

Delta T, or ∆T, specifically relates to the difference in temperature between the water circulating in the central heating system and that of the ambient or room temperature.

Delta T50

Delta T50 is the UK standard for all domestic gas boilers and is set to allow professionals, end-users, and consumers alike, to make a fair and reasonable comparison of radiator and towel rail outputs from various suppliers and across a mix of product types. All outputs should be quoted at Delta T50.

Designer Radiator

A designer radiator offers heat and warmth coupled with stylish designs that can be a focal point of any room in a home.

Digital Heating Element

A digital heating element is designed to regulate the internal temperature whilst providing a digital display screen for ease of use. Some digital elements can be controlled with your mobile device via Wi-Fi.

Double Radiator

Put simply, a double radiator has two panels or two rows of tubes, which produces a higher heat output without taking up any extra space. See also: [Single or Double Radiator?] .

Dual Fuel

Typically found in towel rails where it can function as part of the central heating system, or as an independent heat source. This type of radiator is ideal for heating one room or area during the Summer, without having to heat the whole house.



A heated towel rail element allows you to convert your central heating towel rail into an electric towel rail. Inserted into the collector, it works like a kettle or immersion heating element.

Extruded Aluminium (Radiators)

Extruded aluminium is a metal shaping process that involves forcing a preheated or cold aluminium billet through a die profile that has a specific cross-sectional shape. Aluminium is a popular radiator material these days due to its inherent thermal properties.


Fan Assisted

Whereby the radiance of heat is ‘assisted’ or boosted by the inclusion of fans.


Providing a way to ensure your radiator stays in place which may or may not be load-bearing (ours are!). If feet are not load-bearing, the radiator will still need to be wall-mounted. [See also: Cast Feet, Slip-on Feet & Welded Feet].


Radiator fins are thin sheets of metal designed to increase the surface area of the radiator, and thus improve the rate of heat transfer to the room.

Flat Panel (Flat Fronted) Radiators

Usually defined by a flat front (hence the name), these radiators offer a modern and simple design, whilst being less intrusive and square or rectangular in design.

Flat Tube Radiator

Flat tube radiators have a clean, minimal appearance, combining the structure of tubular radiators with a flat appearance.

Flow & Return

The ‘Flow’ pipe carries hot water from the boiler to the radiator, while the ‘Return’ pipe carries the cooled water from the radiator back to the boiler to be reheated.

Fused Spur

Fused spurs are used instead of conventional plug sockets with higher power, higher voltage electrical devices, used to isolate said electrical devices from the mains supply.



The process of applying a protective zinc coating to steel or iron.

Galvanised (Copper) Finish

In a process similar to Chroming, a layer of copper is applied to the radiator and then hand-finished to produce the desired effect.


Heat Loss

Heat loss refers to the amount of heat energy that escapes from a building or a home, usually through doors, windows, floors, walls, and the roof. A heat loss calculation will typically be measured in either BTUs or kW.

Heat Output

This is the amount of heat that a radiator or heated towel rail gives off. Heat Output is measured in BTUs and Watts and provides a way to determine whether or not the radiator/towel rail will sufficiently heat the room.

Heated Towel Rail

A small type of radiator usually found in a bathroom, ensuite or kitchen, primarily used to hold towels and keep them dry until needed. Some Heated Towel Rails may also feature a high enough heat output allowing it to also heat the room adequately.

Heating Element

Generally used with heated towel rails to provide the source of heat independent of the central heating system.

Horizontal Designer Radiator

A radiator whereby the width is greater than its height. Suitable for any setting, a horizontal radiator can look great as a contemporary statement or a traditional feature.

Hydronic Radiator

When a radiator is described as ‘Hydronic’, this simply means that it utilises hot water from your boiler to heat your home, compared to using something like an electrical element.



Inhibitor is an essential chemical liquid that is added to the water inside the central heating system, formulated to help against corrosion and rust.

IP Rating

An IP Rating or ‘Ingress Protection’ Rating, is an internationally recognised classification system, which grades the resistance of an item against foreign bodies such as dust or liquids.






Lacquer Radiators (Bare Metal Lacquer)

Also known as Bare/Raw Metal Lacquer, these radiators have a clear gloss lacquer applied (as opposed to being painted a colour), which protects the radiator while also accentuating its individuality. [See Ancona Bare Metal Lacquer]

Laser Cut

A method by which metal is cut to size and shape using a laser. This laser uses a thin & focused beam to vaporise material, thus creating the desired cut.

Lockshield Valve

The lockshield valve is designed to restrict the flow of hot water out of a radiator so that it diverts to others. Typically covered with a white cap, the lockshield is an important tool in ensuring your system is balanced and heating up equally.

Lot20 EcoDesign Directive

This directive was created so that all energy-using products (electric radiators in our instance) would have a framework of basic requirements to make them as efficient and eco-friendly as possible.


Manual Valve

A manual valve maintains the temperature of the radiator regardless of how warm the room is. The control of the radiator temperature can be adjusted by hand by turning the valve either up or down. [See also: Valves]


The Manufacturers' Association of Radiators and Convectors - an organisation established to give a particular voice to the radiator and convector industry, focussing on the specific needs of, and issues faced by, manufacturers and distributors of radiators with factories in the UK and/or Europe. MARC also ensures fairness and conformity across the industry.

MOA Element

A heating element used with Towel Rails that is equipped with an electronic temperature sensor to ensure precise temperature control.


NOW Valves

With IRSAP NOW Intelligent Valves you control the temperature intelligently wherever and whenever you want via smartphone.


Open System

An open system is gravity-fed, open to the atmosphere and contains a Feed and Expansion Tank which is located at the system's highest point - typically the loft. This height difference is what facilitates the flow of water.

Oval Tube Radiator

This refers to the oval shaped tubes in our Tubular Radiators.


Pipe Centres

This is a measure of the distance between the inlet and outlet pipes on your radiator, found by measuring from the centre of one pipe to the centre of the other. [See our article on pipe centres]

Programmable Thermostat

A thermostat which allows the user to pre-program their heating devices to operate at a pre-set temperature, and schedule of times – such as just before you wake up or arrive home from work.


PTFE Tape is a polytetrafluorethylene film tape commonly used to seal threaded plumbing fittings like radiator valves, pipes and elements.





Radiators are heat exchangers used to transfer thermal energy from one medium to another for the purpose of cooling and heating – hot water or steam is delivered to a radiator by natural convection or by a pump in your boiler via copper or plastic pipes.

RAL Colours

RAL is a colour management system used in Europe, with each colour identified by a unique RAL code. Check out the range of RAL Colours we offer here. E.g. RAL 7016 = Anthracite Grey. These colours are used in a wide number of industries, and aren't limited to the world of radiators.

Round Tube Radiator

This refers to the round shape of the tubes in our Tubular Radiators.



Individual sections that are joined together to make up a radiator - typically Aluminium, Column or Cast Iron radiators. Sections provide the flexibility to produce radiators of varying widths and heights.

Side Loading Towel Rail

Unlike traditional towel rails, the bars are open down one side to allow towels to be loaded onto the towel rail from the side.

Slip-on Feet

These are floor-mounted and weight bearing, designed to add an extra touch of style and finish to column radiators.

Single Radiator

A single radiator has one panel or one row of tubes, whereas a double radiator has two panels or two rows of tubes. You can see this by looking at the radiator side on. [Single or Double Radiator?].

Smart Heating

A Smart Heating system is typically one that can be controlled remotely and managed on an Android or Apple device via Wi-Fi.

Square Tube Radiator

This refers to the square shape of the tubes in our Tubular Radiators.

Stainless Steel

Stainless Steel is an alloy of Iron that is resistant to rusting and corrosion, perfect for kitchens & bathrooms.

Steel (Radiators)

Steel is an alloy of iron and carbon with improved strength and fracture resistance compared to other forms of iron. Steel is the most popular and commonly found material when it comes to household radiators in the UK.

Straight Valve

A valve designed to accommodate pipework that projects directly up from the floor and connects to the base of the radiator. [See also: Valves]



A thermostat is a regulating device that automatically regulates temperature, or that activates/shuts down a device when the temperature reaches a certain point.

Thermostatic Radiator Valve (TRV)

A Thermostatic Radiator Valve monitors the room temperature and automatically opens and closes the radiator valve to control the radiator temperature, which in turn maintains the desired room temperature level.


A T-Piece will enable you to turn a central heating-fed towel rail into a dual fuel towel rail by allowing you to also connect an electrical element.

Traditional Radiators

Vintage in style, but created using the highest contemporary standards, traditional radiators are perfect for period restorations, but equally brilliant in modern homes adding a splash of vintage charm.

Tube/Tubular Radiator

Tube or Tubular radiators are a type of radiator that utilises a series of tubes in its construction to distribute heat throughout a room.

Type 11 Radiator

A Type 11 radiator is a type of radiator that has a single panel paired with a single set of convector fins on the rear.

Type 21 Radiator

A Type 21 radiator pairs 2 panels – 1 on the front and one on the back with a single set of convector fins between them.

Type 22 Radiator

A Type 22 radiator pairs 2 panels – 1 on the front and one on the back with 2 sets of convector fins between them.





Radiators Valves control the operation of each radiator in a home. They are as important to the performance of the heating system as the radiators themselves. Radiator Valves typically come in pairs, one called a lockshield, the other a wheelhead.

Vertical Designer Radiator

A radiator whereby the height is greater than its width, particularly suitable for narrow walls/spaces. Vertical Radiators are a great way to transform limited available space, freeing up room and adding much-needed warmth.


Wall Ties

Wall ties are non-loadbearing and are used to secure the top of a floor-mounted cast iron or steel column radiators to the wall, preventing them from being pulled over.


The wattage of an electric radiator refers to its maximum output of electrical power.

Welded Feet

These load-bearing feet are welded to the outermost section of the radiator on both ends to provide support to a radiator that sits on the floor (as opposed to being wall-mounted). Depending on the width of the radiator, more may be required in the middle sections.

Wheelhead Valve

The Wheelhead Valve is used to adjust the flow of water into a radiator. These are paired with a Lockshield Valve which is used to balance the flow of water out of the radiator and around the system.







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