How to make underfloor heating

WhereWater and heatingUnderfloor heating

Steps

  1. In the Zones and thermostat row, choose a zone: Hydronic floor heating, Cable or Infrared heating film.
  2. Draw it on the plan. The Floor heating zone window opens on the right, with Drawing method in it:
    • Rectangle: drag with the mouse, anything beyond the wall is trimmed off. A click without dragging gives the zone the whole room, even an L-shaped one;
    • Point by point: click the corners of the outline, they stick to the walls. Close it by clicking the first point, with Enter or with a double-click.
    Corners move by grid cell, with Ctrl exactly under the cursor. A zone is placed only inside a room and does not overlap another one. The tool stays on for the next zone.
  3. In 3D, a zone is placed with a click on a room, covering the whole room.
  4. Hydronic floor: place a manifold (the Manifold and supply row) and click Build in the Manifold pipes step. In the zone window, choose the laying pitch (15 cm by default).
  5. Electric floor: in the zone window, enter the specific power, W/m², and place a thermostat in the room (the Thermostat tile; it is also in Electrics).
  6. To adjust the outline, select the zone: circles appear at the corners, small squares on the sides. You can move, rotate and copy the zone, but it will not go beyond the wall.
  7. Wall heating is placed from the Zones, wall heating and thermostat row: it is a strip on the wall, its width and height define the heating part. Enter the specific power, W/m², in the window.

Zone keys: rectangle

What to pressWhat happens
Dragdrag: rectangle along the walls
Clickclick: whole room
Escturn the tool off

Zone keys: point by point

What to pressWhat happens
Clickplace an outline corner
Shiftside strictly horizontal or vertical
Backspaceremove the last point
Enteror×2Double-clickclose the outline (or click the first point)
Escreset the outline; again: turn the tool off

Zone editing keys

What to pressWhat happens
Dragby a circle: moves the corner
Dragby the square in the middle of a side: adds a corner (a click in the middle, drag where you steer)
×2Double-clickon a circle: removes the corner

What is important to know

  • The zone's area is written in its middle, the side lengths next to the sides. Lengths are in the project unit, like room dimensions: in millimetres without a label, in centimetres and metres with one. Sides lying on walls are labelled by the room dimension. A zone covering the whole room does not write its area: its area is the room area.
  • The floor is no warmer than 29 °C in rooms and 31 °C in bathrooms and corridors (SP 60, cl. 14.18). If such a floor does not cover the heat loss, a radiator is also needed.
  • Hydronic floor: a loop no longer than 100 m (manufacturer data), heat carrier no hotter than 50 °C, with hot supply a mixing unit is needed. An electric floor is no more powerful than 200 W/m² (manufacturer data).
  • Under a bathtub, shower tray, toilet and cabinets the floor is not laid: the calculation will say so.
  • Wall heating warms like an electric convector. Its surface is no warmer than 40 °C (SP 60, cl. 14.18); the calculation estimates it as t_in + W/m² ÷ 8.7 (coefficient from SP 50.13330.2024, Table 4). Heating elements are placed only in a multilayer exterior wall (cl. 14.17).