Glossary of Central Heating Terms

If you think your heating engineer is speaking a foreign language when using the trade jargon to discuss your central heating system, please don’t hesitate to stop him in his tracks and ask him/her to explain anything you don’t understand.

To help you get to the bottom of some of the most common central heating terminology, we’ve compiled this useful glossary:

• Angled Radiator Valve – Valves that connect a radiator or heated towel rail to the pipework at a 90 degree angle.
• Ambient Temperature – the temperature of the surrounding air.
• Backflow – a flow of water that has reversed because of a loss of system pressure.
• BAR – a metric measurement of pressure that is equal to the pressure at sea level on earth.
• Biomass – refers to fuel that originates from plant or animal matter.
• Blanking Plug – used to close an opening on an unused radiator inlet, available in different diameters, threaded or unthreaded.
• Bleeding a Radiator – Use a radiator bleed key to open the valve on a radiator to expel excess air to improve radiator efficiency.
• BTU – This is an acronym for British Thermal Unit, the amount of energy needed to raise the temperature of a pound of water by one degree Fahrenheit. You need to know the BTU of a radiator to make sure it has sufficient capacity to heat a specific room.
• Carbon Monoxide – an invisible poisonous gas which has no smell created from improperly burnt fuels such as gas, coal and wood.
• Central Connection – this type of radiator has a valve inlet in the centre of the bottom of the radiator, rather than on each side as is usually the case.
• Combi (Combination) Boiler – a highly efficient water heater and central heating boiler in a compact unit, supplying hot water directly to taps or radiators without the need for a storage tank.
• Condensing Boiler – As a boiler burns fuel it produces water vapour or steam which is usually expelled from the flue pipe. A condensing boiler recovers the vapour and recycles the heat from it to stop it from being wasted.
• Economy Seven – an electricity tariff that offers seven hours of cheaper electricity during the early hours of the morning.
• Economy Seven – an electricity tariff that offers seven hours of cheaper electricity during the early hours of the morning.
• Flow and Return – this term is used to designate where water flows into one side of a radiator and out of the other, returning to the boiler to be reheated.
• Heat Exchanger – A heat exchanger is a device that transfers heat from one fluid to another. In a boiler this means transferring heat from gas to the water that circulates around the radiators.
• Inhibitor – A chemical liquid that is added to the water in a central heating system to protect it from corrosion.