Retrofitting Low Profile Underfloor Heating in Large Rooms - How could it work?

The FLEXIRO system is designed for retrofitting areas of up to 10 m2 with a water underfloor heating. The 10 mm thin PE-RT pipe facilitates flexible laying patterns as well as a low construction height of only 17 mm. Therefore the FLEXIRO underfloor heating can be retrofitted on top of existing surfaces. In most environments an additional thermal insulation is not required.

Compared with conventional underfloor heating systems the thin FLEXIRO pipe has a considerable friction pressure. It correlates with the pipe length and reduces the flow pressure of the existing heating installation. As we want the FLEXIRO kits to work in all heating installations, we have limited our heating kits to 4 heating circuits with 30 m PE-RT pipe each. In consequence our kits have a maximum size of 10 m2.


My Room is larger than 10 m2. Can I use FLEXIRO Underfloor Heating Kits nevertheless?

Option 1Adjust the thermally activated area

In many constellations it is not required to thermally activate the complete room. The heating power of an underfloor heating is adsorbed beneath cupboards, kitchenette or bathtubes. Additional area gains are made by the distance between pipes and walls, which should be 10 cm at least. With good planning and a well thought-out distribution of the sanitary facilities, the 5sqm kit is usually sufficient for thermal activation of a 10sqm bathroom. Make a detailed planning sketch of the rooms that are to be retrofitted with underfloor heating. This can be used to calculate the actually required thermally activated area. In many cases, the total area of the room is significantly larger than the area of the underfloor heating.

Option 2Connect heating kits

Our DIY underfloor heating kits can be combined for larger rooms. However, each kit must be connected to its own Kompabox. Usually, larger rooms were heated using several radiators before the conversion. The resulting connection options can also be used for the underfloor heating kits. The laying of a 32sqm room might look as follows by using two 10sqm sets.

The Multibox 4K-RTL with the possibility of smart home extension offers a particularly convenient way of uniformly controlling several heating kits. However, the regulation of underfloor heating is rarely changed in everyday life once the optimal room temperature has been found and the concealed installation renders the Kompaboxes barely noticeable.

Option 3 Individual solutions

We are trying to support DIY-Builders with the implementation of their underfloor heating as good as we can. For some initial conditions, low profile systems are simply not suitable. In all other cases, we are happy to discuss possible solutions and make individual offers. Ask our technical advisors.

Retrofitting Underfloor Heating in Bathrooms » What you need to know

  • How do I calculate the heating surface?
  • What heat output is possible?
  • How do I protect the floor structure from splashing water?


We provide answers to the most important questions when retrofitting underfloor heating in bathrooms.