| When planning a primary, electric underfloor | | | | into a low level radiator and walking over it, the |
| heating installation, where the floor heating system | | | | human foot factor limits the maximum floor |
| is providing the sole source of room heating, it is | | | | operating temperature to a maximum of 27-28 |
| important to take into consideration some basic | | | | degrees Celsius. |
| principals. | | | | Electric underfloor heating systems are controlled |
| All structures lose and retain heat according to | | | | using a digital thermostat. The controller can be |
| their U-values. The U-value is a measure of how | | | | programmed with 4 on/off settings over a |
| much thermal energy will pass through a square | | | | 24-hour period. Once the floor heating reaches |
| metre of structure when air temperatures on | | | | the programmed floor and room temperature |
| either side differ by 1 degree Celsius. The fabric | | | | settings, the thermostat will cycle on and off |
| of any building will typically consist of a number of | | | | continuously (within 1 degree C) to maintain these |
| components, each with their characteristic | | | | settings. |
| resistance values; the U-value is a combination of | | | | The floor heating will radiate heat energy |
| all these values. | | | | uniformly, warming the room evenly to your |
| In designing a primary under floor heating system, | | | | preset ambient thermostat settings, maintaining a |
| greater consideration of these factors of heat | | | | comfortable room temperature; providing heat is |
| loss and heat gain need to be taken into account. | | | | not being lost to the outside by poor insulation (U |
| For a typical convection heating system, on cold | | | | Value) and frequent changes of air (drafts). |
| days, where the temperature on the outside of | | | | With a high performance insulation layer between |
| the structure is low, the room heating can be | | | | the heating cable and the sub-floor below |
| increased by turning up the boiler and opening up | | | | (concrete or wood), the underfloor heating will |
| the radiators to improve the heat output. | | | | operate efficiently and very effectively. For |
| On the other hand, an underfloor heating system | | | | cement sub-floors where no insulation can be |
| acts as a low-level heat source, radiating thermal | | | | fitted, a high-output (200W/m2) heating mat is |
| energy into the room as radiant heat. Unlike a | | | | normally recommended to compensate for the |
| traditional convection heating system, where a | | | | heat loss into the concrete slab below. With no |
| wall radiator or freestanding heater is used as sole | | | | insulation, the floor heating would otherwise be |
| source of room heating, the under floor heating | | | | very slow to reach operating temperature; the |
| cannot be turned up to produce a higher heat | | | | extra output capacity of a 200Wm2 heating mat |
| output, due to the comfort factor on the feet. | | | | is used to good effect to bring the floor up to |
| Effectively, because we are converting the floor | | | | operating temperature quickly. |