How does a water underfloor heating system work?
A brief explanation of how underfloor heating works.
Warm Water Is Pumped Through Pipes In The Floor
Plastic pipes specifically designed for underfloor heating are laid, at even spacings, under the floor in a sand and cement screed. Warm water is pumped through the pipes and the heat from the water transfers to the screed. The entire floor slowly heats up, and once up to temperature, evenly heats the air above it.
The Whole Floor Becomes A Low Temperature Radiator
Unlike radiators which heat a relatively small and focussed area, an underfloor heating system uses the entire floor area of each room to emit heat so doesn't need to run at high temperatures. Typically, the temperature of the water in an underfloor heating system is between 35 and 55 degrees Celsius - depending on the floor construction.
The Floor Warms Up
The floor temperature will be between 25 – 33 degrees Celsius when the system is on, which feels nice to walk on and means the air temperature is higher at your feet than around your head. The result is a heating system that is not only highly efficient but extremely comfortable too.
The Air In The Room Is Heated To The Desired Temperature
Thermostats in each room regulate the air temperature by turning on and off the flow of warm water passing through the floor. This allows the temperature of the different rooms or zones in a building to be controlled individually and extremely accurately.
The Water Is Heated By A Boiler Or Heat Pump
Warm water can be provided by either a boiler or a heat pump and is distributed to the underfloor pipework by a stainless steel manifold. The manifold is the hub of the system and is needed to control the flow, temperature and direction of the water.
Efficiency Can Be Improved
The efficiency of an underfloor heating system can be improved by lowering the water temperature and increasing the amount of pipe in the floor. Underfloor heating systems with pipe at the correct spacings can operate effectively with flow temperatures as low as 35 degrees Celsius.
Insulation Under The Heating Pipes Stops Heat Being Lost Downwards
For an underfloor heating system to work correctly, adequate insulation must always be fitted below the heating pipes and screed so that the heat is emitted upwards and not lost downwards into the concrete sub base or any air space under the floor.
Choosing The Right Floor Finish Is Crucial
The floor finish must not insulate the screed and stop the heat getting through to the room. Tiles and stone slabs, any wood flooring up to 22m thick and combinations of carpets and underlay up to 1.5 Tog are ideal floor finishes.
