How It's Done: Retrofitting Underfloor Heating with Pre-milled Drywall Plasterboards

FLEXIRO DRY-LINED UNDERFLOOR HEATING KIT DELIVERY CONTENTS

The full scope of the kit can be found in the installation instructions PDF.

Further accessories and suitable tools can also be found in the FLEXIRO shop.

NOTE:

The following also applies for the FLEXIRO thin-bed underfloor heating system: Work on heating systems calls for adequate manual skills and abilities. If necessary, engage a professional to carry out the installation work.

IMPORTANT ADVICE BEFORE INSTALLING

Determine the arrangement of the heating circuits. The installation site of the Kompa box is chosen such that the heating pipes of all heating circuits can be routed directly up this box without needing to be extended.

Caution: Kit 4.5 m² = 1 heating circuit; Kit 6.0m² = 2 heating circuits; Kit 7.5m² = 3 heating circuits and Kit 12.0m² = 4 heating circuits.

In principle, the pipes of the underfloor heating system can be shortened. However, attention needs to be paid that the difference in length of the individual connections does not become too great (max. 15%).

IMPORTANT ADVICE BEFORE INSTALLINGN

The dry-lined underfloor heating system may be operated at system temperatures up to a maximum of 54°C.

Higher temperatures will damage the gypsum fibreboard. Avoid crossing the pipes in order to exploit the full benefits of the low construction height of the thin-bed underfloor heating system.

Make sure that pipes are always cut off straight and burr-free. Pipes must be neither pinched nor kinked.

PREPARING FOR THE INSTALLATION

The existing substrate must be a level, clean, load-bearing dry screed surface of gypsum fibreboards.

Create a layout plan for the arrangement of the pre-milled dry screed panels so that the heating pipes can be laid from the KOMPA box and back to the KOMPA box without overlaps. Before laying the pipelines, determine the position of the connection distributors for the underfloor heating so that you know exactly where the pipelines must run to.

Please ensure that the control valve can always be reached subsequently. After installing the distributor, the pipe ends must still be pluggable into the individual connections.

INSTALLING THE KOMPA BOX SINGLE ROOM CONTROL

In order to provide efficient temperature control, the KOMPA box should be positioned in such a way that the thermostatic head can detect the temperature of the indoor air and .the air can flow around it unhindered.

The separately enclosed installation and operating instructions must be observed.

FITTING THE EDGE INSULATION STRIP

A continuous edge insulation strip is to be fitted to all walls or vertical building components. This must reach up to the top edge of the top coating.

The edge insulation strip is cropped once the top layer has been fully laid (with tile-laying only after grouting).

Laying FLEXIRO screed panels

Before installation, the planned heating area should be marked out on the floor and the screed panels cut to size as necessary. For cutting to size, use a held-held circular saw, a jig saw or a hand saw with a suitable blade.

Watch out: The pre-milled screed panels are needed only for the intended heating area. Standard screed panels are prepared in the unheated edge areas and to completely fill the 3rd layer.

Laying FLEXIRO screed panels

The pre-milled screed panels are glued to the existing finished screed with screed adhesive (PU adhesive) and additionally secured with. drywall screws or staples.

The feed panel must be aligned such that the heating pipes can be laid to the KOMPA box.

Laying FLEXIRO screed panels

The adhesive is applied to the floor.

No all-over application of the adhesive is required. Lines of adhesive are sufficient. Detailed information can be found in the panel manufacturer's advice leaflet.

Laying FLEXIRO screed panels

It must be ensured that the grooves in the FLEXIRO screed panels of the separate panels are aligned to one another so that the installation of the heating pipes is later possible.

Laying FLEXIRO screed panels

The pre-milled screed panels are additionally secured to the existing finished screed with drywall screws or staples.

Laying FLEXIRO screed panels

If necessary, the installer can cut additional groves on site in the blanking panels or the the active panels using a surface milling cutter and a suitable 10 mm semicircular milling cutter.

Laying the heating pipes

The optimum starting point for laying the heating pipes is near the distributor arms, to keep the pipe length for the connection as short as possible.

The minimum spacing between the pipes is 10 cm. The distance between the underfloor heating and the room walls should be at least 5 cm.

Laying the heating pipes

A minimum bending radius of 5 cm must always be maintained in areas where the pipe bends – we recommend keeping the radius as large as possible.

Laying the heating pipes

Cut out any kinks or damaged areas on the heating pipes. The pipe must be reconnected with a permanently tight coupling (under accessories see plug-in connector). The coupling must be protected from direct contact with the grouting compound or top coating by wrapping it in PE film. The position of the coupling must be marked. After this repair the pipes may have to be extended. If a coupling has to be used, the screed panel in this area must be opened out (milled or similar) to the depth and width of the coupling.

Laying the heating pipes

Care must be exercised if you have to step on the screed panels while laying the pipes.

The pipes must be laid without any twisting.

Laying the heating pipes

Various patterns of laying are possible: Laying in a spiral (bifilar) pattern is particularly advantageous. Besides very even distribution of heat, it allows large radii which makes it easier to avoid twisting the pipes.

Before sealing the grooves with a suitable joint filling compound, it must be ensured that the pipe is fixed in place everywhere and not jutting out of the grooves.

Connection to the Kompa box

The distribution arms are connected to the KOMPA box with a Eurocone screw connection. The Eurocone has a self-sealing effect while the metal screw connection has a purely safety function. Over-tightening should absolutely be avoided as this would compromise the safety of the heating system.

Connection to the Kompa box

The arrangement of the heating pipes in the Kompa box is shown here. The heating pipes are connected to the distributor arms by means of a simple plug-in assembly. The heating pipes that have just been cut and possibly shortened are inserted directly into the plug-in connections of the distributor arms right up to the stop.

Anschluss an die Regelbox "KOMPABOX RTL"

Hier wird die Anordnung der Heizungsrohre an der Kompabox RTL dargestellt. Der Anschluss der Heizungsrohre in den Verteilerfingern erfolgt über eine einfache Steckmontage. Die gerade abgeschnittenen und eventuell eingekürzten Heizungsrohre werden direkt in die Steckanschlüsse der Verteilerfinger bis zum Anschlag gesteckt.

Pressure testing the heating system

Make sure that the system and all associated components are correctly installed before operating the underfloor heating system. The pressure testing pump is offered as an accessory.

Be sure to carry out a trial run before sealing sealing the pipe system with joint filling compound. This is your last chance to correct installation errors or repair damage.

Applying the joint filler

To seal the grooves in the FLEXIRO screed panels, use a joint filling compound or alternatively a gypsum-based joint filler that manufacturer's earmark for the filling of gypsum fibreboards.

Applying the joint filler

Before you start applying the construction chemical products, make sure that the underfloor heating is fully out of service. The heating pipes then need to be trowelled over with a flexibly hardening joint filling compound. Also seal all unused grooves in the screed plates with joint filling compound.

Applying the top covering

Once the joint filling compound has dried thoroughly, you can apply the desired top covering. Observe the manufacturer's instructions with regard to the preparation of the sub-surface.

All floor coverings and adhesives must be rated "Suitable for underfloor heating systems" by the respective manufacturer.

Applying the top covering

The laying of ceramic or porcelain tiles 330x330mm in size presents no problems at all. Please clarify with the manufacturer in advance whether larger tile sizes are suitable for the floor structure.

Further advice about dry screed materials: Again, we point out that the relevant statutes, ordinances, directives and standards must be adhered to when planning and installing heating systems and carrying out the dry-lined construction work.

Commissioning (heating-up process)

After completion and once the surface covering has dried naturally, the heating-up process is carried out. If you have laid tiles, do not begin operating the underfloor heating system until the tile adhesive has completely hardened. The heating-up is usually carried out according to a heating-up protocol. It is essential that you follow the manufacturer's instructions in this regard.

Sketch: Meandering laying pattern.