Floor tiling with underfloor heating or under tile heating

Floor Heating Systems

Introduction



Types of Underfloor Heating

Underfloor heating systems are, essentially, of two types. "Wet", or hydronic, underfloor heating systems typically involve laying pipe work beneath the surface of the floor, often embedded in the floor screed, at the time of construction. Warm water from a boiler – at a temperature of around 50°C, and therefore much cooler than a traditional radiator system – circulates around the pipe work, and the temperature in each room is controlled by a thermostat. The difficulty with wet underfloor systems is that, because pipe work needs to be embedded beneath the floor, they are much better suited to new build, rather than retro fit, projects. Indeed, in many situations, logistic and space constraints may mean that wet underfloor heating systems are very difficult, if not impossible, to install in existing properties, and are very expensive if installation is a possibility.

"Dry", or electric, underfloor heating systems, on the other hand, involve a conductive, dual core heating cable – either loose, or woven into tough, fibreglass mats, for ease of installation – which can be laid onto the subfloor, without disturbing the existing floor, or raising its height by more than a few millimetres. This means that electric underfloor heating is much better suited to retro fit projects than the wet alternative. Electricity flows through the heating element, which becomes warm – in a similar method to the heating element in an electric fire, or kettle – and heat is radiated to the subfloor, floor covering and hence to the room above. Typically, there is just one wire than needs to be connected to a thermostat in each room, or zone within your home, although this should be done by a qualified electrician.

Floor Coverings & Underfloor Heating

Electric underfloor heating, nowadays, is suitable for installation beneath all types of floor covering, although the characteristics of the heating cable, or heating mat, and the floor covering, itself, need to be taken into account. Stone or tile floors typically require heating cables or mats with higher heat output per square metre, measured in W/m2 ("Watts per square metre") than, say, solid or engineered wood flooring. A heat output of 150W/m2 or more may be suitable for stone or tile floors, but wood, or other types of flooring, may require outputs of 100W/m2 or less. While higher wattage means that stone or tile floors in exposed areas, such as conservatories, heat up quickly and maintain a comfortable heat, it may present the risk of damage, or even fire, if used incorrectly beneath other types of flooring. The moisture content of wooden flooring should also be 10%, or less, to prevent shrinkage or !warping under the effect of underfloor heating. The use of thick underlay beneath carpet, or any other floor covering, should also be avoided.