Glossary of Common Underfloor Heating Terms and Phrases
Explore our glossary of common terms and phrases related to underfloor heating
Actuator
A device that regulates the flow of water in heating systems, enabling precise control.
Air Source
A type of heat pump that uses external air to heat or cool indoor spaces.
Anhydrite
A white or pale bluish mineral commonly used in the screed of wet underfloor heating systems.
Balancing Valve
A type of valve that maintains the hydraulic balance found within piping systems.
Biocide
A substance that prevents and fights against bacterial and fungal contaminations.
Bivalent System
A type of heating system that combines heat pumps with other heat sources, such as boilers.
Bleed
The process of removing trapped air from underfloor heating systems to enable water circulation.
Blending Valve
A type of valve that mixes warm and cold water to regulate the fluid temperature of a heating system.
Building ‘Envelope’
Broadly refers to the foundation, walls, roof and windows of a building.
Coefficient of Performance (COP)
A factor linking the energy input and output of a heating system, showing system efficiency.
Commissioning
The act of carrying out final checks and adjustments to make a heating system ready for use.
Coupling
A small device that serves to couple or connect adjacent parts in a heating system, such as pipes.
Crimp Fitting
A coupling subtype that joins pipes by lateral sleeve compression, forming a secure, leak-resistant seal.
Curing
The process by which freshly laid screed hardens or sets before an underfloor heating system is activated.
Dead Band
The temperature range around a thermostat’s setpoint during which the heating system remains dormant.
Decoiler
A device that unrolls or unwinds a pipe from its coiled state, preparing it for installation.
Decoupling Membrane
An isolating layer placed beneath or around pipes, serving as a shield from structural stress.
Dew Point
The temperature threshold at which air becomes saturated and condensation begins to form.
Dry System
An underfloor heating system that remains free from wet screed and uses pre-formed channels to house pipes.
Egg Crate
A common type of floor panel with egg-shaped protrusions, used to separate pipe loops in underfloor heating systems.
Emissivity
The capacity of a floor surface to radiate heat efficiently within an underfloor heating system.
End Loop
The return bend at the furthest point of a pipe circuit, where the pipe curves back into the return leg.
Floating Floor
A floor system in which heating pipes are positioned above the insulation and covered with panels, rather than embedded in screed.
Flushing
The process of running clean water through an underfloor heating system to remove debris before use.
Glycol
A clear, viscous liquid added to wet underfloor heating systems to prevent freezing and protect against corrosion.
Ground Loop
A pipe circuit embedded in the ground that transfers thermal energy to or from a heat source or heating system.
Ground Source
A heat pump that extracts thermal energy stored in the ground to heat or cool indoor spaces.
Gudeul/Ondol
A traditional Korean underfloor heating system in which wood fire smoke flows beneath the floor to provide warmth.
Heat Curve
A graphical depiction of the relationship between the heat input and the temperature output of a heating system.
Heat Mapping
The visual representation of heat distribution across a surface or space, often achieved by using a handheld imaging device.
Heat Pump
A device that extracts heat from the air, water, or ground and transfers it to warm or cool indoor spaces.
Heat Retention
The capacity of a heating system to store and release warmth efficiently over time.
Hydronic System
An underfloor heating system that circulates water as the heat-transfer medium, often called a “wet” system.
Hygrothermal
Relates to the interaction of heat and moisture and their combined effect on building materials and systems.
In-Slab
A floor-heating method in which heating elements are integrated in a concrete slab, utilising the slab’s thermal mass to distribute heat.
Lag
The interval between the activation of a heating system and the moment the target temperature is reached.
Load Compensation
The adjustment of a heating system to maintain heat delivery in response to changes in demand or external conditions.
Looping
The arrangement of pipes in continuous circuits, enabling even distribution of warm water.
Low Profile
Thin heating panels integrated into a floor structure to reduce the overall impact on floor height.
Manifold
A multi-outlet distribution device that channels water from a single supply pipe to multiple circuits.
Oriented Strand Board (OSB)
A panel made of engineered wood, commonly used for subflooring in underfloor heating systems.
Overfloor Heating (OFH)
A heating system in which elements are installed above the floor or subfloor rather than embedded within it.
Overlay
A layer placed over heating pipes to provide damage protection and ensure even heat distribution.
Pipe Conduit
A sleeve-like encasement used to protect pipes as they journey through floors, screeds, or walls.
Pre-Grooved
Relating to a board or panel that has been furrowed/channelled in advance to accommodate pipes or other connective materials.
Radiant Heat
The thermal energy emitted from an underfloor heating system, transferred through direct contact with adjacent surfaces and objects.
Re-Rounding
The process of restoring the roundness of a deformed pipe—often caused by incorrect storage or handling.
Retrofit
The process of adapting or fitting new heating systems or components into an existing building.
Screed
A layer of material, usually sand-cement or anhydrite, applied over a floor to form a smooth, level surface.
Subfloor
The structural layer found below finished floors, usually made of beams, panels, or boards.
Thermal Break
An insulative layer of material used to reduce heat loss by interrupting the flow of thermal energy.
Thermostat
A device that automatically monitors and adjusts the output of an integrated heating system.
Underfloor Heating (UFH)
A heating system embedded within a floor structure, delivering radiant heat to the space above.
Underlay
A layer of material installed beneath floor coverings to provide insulation, noise reduction and floor protection.
Wet System
An underfloor heating system that circulates water as the heat-transfer medium, often called a hydronic system.
Yield
Refers to the level of heat or performance generated by a heating system, as a result of the energy supplied to it.
Zone
A defined area within a floor plan that is independently heated, typically served by its own circuit, thermostat, or manifold.
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