Underfloor heating is a means of heating a building through a series of pipes that are encased in the floor screed.
The dense floor screed which heats up, surrounds the pipes and in turn acts like a large, room sized, radiator . The heat from the underfloor is evenly distributed throughout the room(s) being served. Therefore there will not be cold areas within the room, which can happen in radiator served rooms. The controls for underfloor heating means that separate areas can be heated to the desired temperatures which will give the required comfort levels to the occupiers. Each room or area is served by one continuous loop or loops. Our loops will never have joiners and will be a maximum of 95 meters in length. This therefore guarantees that the heated water flowing through the underfloor will be able to travel through the pipework at proper velocities without suffering from inertia.
The insulation under the underfloor pipes should be a quality foil backed rigid foam board that complies with the current building regulations. These regulations can stipulate that where underfloor heating is being installed the U-value needs to be reduced compared to conventional heating systems. This is a sensible approach as we are heating from the ground up and therefore want to minimize the amount of heat loss that can occur with lower levels of insulation. A perimeter-insulated upstand should also be used around all walls built up from the foundation to reduce thermal bridging.
There are two main types of screed used in Ireland. A sand and cement screed is the most common. Typically this should be no more than 80mm on top of the insulation. If the screed is much deeper the underfloor heating will take longer to respond and potentially the concrete could have to be re-enforced.
The other type of screed is a hemi-hydrate pour on screed. This screed is much denser and stronger than a sand and cement screed and thus it only requires to be poured to a depth of about 40mm. It is also self-leveling so there is no need for additional compounds to level the floor for laying floor coverings. Most tiled floors are suitable as they have excellent thermal conductivity properties. Some timber floors can be used but it is preferable that they are glued to the screed with a special mastic that moves with the timber expanding and contracting. A small number of carpets that have reduced thermal resistance can also be used.