Safe shopping by GeoTrustGlossary
Sealed heating system
Combination and other boilers where there is no feed and expansion tank and so it is self-contained
Air Bleed
Device to let air out from a radiator or another high point to maintain its continuous heat
Air separator
Connects to the cold feed and expansion on open systems and removes air from the system to stop the oxygen within the air corroding the radiators from the inside
Air Vent
Let’s air into a cupboard or room. It is also regarded as a valve, either manual or automatic, to remove air from the highest point of a coil or piping.
Balanced Flue
A natural draft room sealed appliance
Boiler
An appliance to heat water (a.k.a. a heat generator).
Bypass
A link between the flow and the return to allow a continuous flow of water through the boiler
It is usually more efficient to have an automatic bypass valve fitted, normally near the boiler or the cylinder. You might find that when replacing your boiler, you may need to fit TRVs and an automatic bypass valve to comply with the Building Regulations.
Changeover valve
Used on combination boilers to swap between heating the property and water
Central Heating System
All the piping, controls & radiator configuration, powered centrally.
Check Valve
A Non-return valve that water can only pass in one direction. A check valve has a spring that will hold the valve closed, and will not allow water to flow until a preset pressure is achieved in the system.
Cold feed
To let cold water from the header tank into the system via gravity.
Cylinder
Place for hot water storage (usually made from Copper) in conventional/system heating systems
Immersion Heater
An electric back up heater for water, where an electric element which screws into the hot water tank. This element is wired to the mains electrical supply via an isolating switch, a thermostat to control the temperature, and sometimes a timer which enables you set the times you wish to have the water heated.
Expansion Pipe
Allows expanded hot air and water from the system to escape into the expansion tank
Expansion Tank
Temporarily stores water that has expanded out of open vented conventional systems. Water flow in and out of the tank respectively using a stop cock and overflow outlet
Expansion Vessel
Used in sealed systems instead of an expansion tank to temporarily store expanded hot water
Filling loop
Used to fill sealed systems with water via the mains supply.
Flow Pipe
Hot water flow from the boiler to radiators or system cylinder
Flue
Where the fumes from the gas goes after burning
Heat Exchanger
Where heat is transferred from the source (gas combustion) to the destination (water)
Lockshield Valve
This is used to balance the radiators in the system so that they all heat up at the same time. The further away the radiator is from the boiler, the more the lockshield valve should be opened.
Motorised valve
Device to alter or stop the flow of water
Open system
A system that has an expansion tank open to the atmosphere (differs from sealed system)
Primary Flow
The flow pipe from boiler to pump before any Motorised valve
Pump
For circulating the hot water around the hot water and central heating system
Pump over-run
This is a facility within you boiler that continues to pump water through the device to stop static water from being excessively heated within the system, usually extending heat exchanger life
Programmer
Contains a lcock and two timer switches (channels) which turn the hot water and central heating supply on at pre-selected times of day
Radiator bleeding
Trapped air in radiator preventing radiator from emitting it’s full heat potential
Return Water
This is water that once cooled in the radiators, it returns to the boiler for reheating
Room Sealed Boiler
The boiler will takes in air for combustion naturally from a draught or via a fanned flue from outside
Sealed System
Water sealed from the atmosphere (needs expansion vessel). It also has pressurised control to safely release excess pressure from the system, usually created from bleeding the radiators or from a leak in the system
Stop Cock
Valve to stop mains water flow into property in sealed and unsealed conventional systems
Thermostat
Device for controlling temperature on a central heating system
TRV – Thermostatic Radiator Valves
In order to control room temperature you should fit TRVs. As the room temperature approaches the position set on the TRV, the valve begins to closes restricting the flow of hot water into the radiator. Some boilers require that a minimum water flow rate is maintained at all times so check with boiler instruction manual.
Vent pipe
Allows expanded hot air and water from the system to escape into the expansion tank
Ventilation
Air vent, either for cooling or supplying air for combustion
Zone Valve
Device to alter or stop the flow of water within a section of the plumbing system (e.g. kitchen)
Last Updated: June 18, 2009
