Nexans N-HEAT MILLIMAT, Manual

4

English

Installation Instructions N-HEAT

®

 MILLIMAT™

Important! Read this before starting the installation

Please read through the entire installation instructions (this document) before 
starting the installation. 

Plan the installation by identifying the heated area, which is the entire room area 
minus areas not to be heated. 

• The heating cable cannot cross neither touch itself and cannot be placed in 

a wall, therefore the area of the MILLIMAT(S) must be slightly smaller than 
the heated area.

• The distance between the mat and any thermal barrier shall be minimum 3 cm 

(1,2 inches). 

• Do not install the mat under permanent installations without legs. This will 

prevent airflow and may cause overheating.

• In floors requiring membranes (wet rooms), the membrane should preferably 

be placed above the mat

• In case some cable is removed from the net and laid freely, the same CC 

distance as on the net shall be observed and used.  

• Any reinforcement net or bars installed above the MILLIMAT must be 

installed in such a way that the cable is not damaged during subsequent 
works.

General guidelines

The installation of this heating product shall be in accordance with the manu-
facturer’s instructions and the regulations of the authority having jurisdiction. The 
product should only be installed only by qualified personnel who are familiar 
with the construction and operation of heating cables and the risks involved.

Product description

Twin conductor heating cable mat designed for electrical floor heating, sup-
plied with factory fitted cold lead (length 2,5 m). The cable is terminated with a 
water tight end seal.

Technical data

Conductor insulation: 

Fluor polymer

Outer sheath: 

PVC

Power:  

As stated on cable/package (Watt)

Rated voltage:  

230V~

Max. operating voltage:  

500V

Max. cont. operating temp.:  

65 °C (149 °F)

Minimum bending diameter:  

40 mm (1 5/8”)

Min. bending diameter  

10 x cable diameter

Resistance tolerance:  

- 5% / +10%

Length cold lead:  

2,5 m

Mechanical class:  

M1

Minimum installation temperature: 

 0 ºC (32 ºF)

Application

The MILLIMAT is suitable for heating all types of indoor rooms and well suited 
for renovation projects. The MILLIMAT is designed for embedding in adhesive/
mortar/screed/concrete and can be installed beneath most floor coverings, 
please see these instructions for further details. MILLIMAT 150 W/m² can only 
be installed on a non-combustible subfloor, while MILLIMAT 100 W/m² is  
approved for installation on combustible surfaces.

Installation instructions – step by step
1.

  Caution! Handle the product with care and do not press or drop sharp 

objects into the MILLIMAT.

2.

  Measure and check the following electrical properties to be within limits 

before installing the MILLIMAT:

  - The ground insulation between the earth wire and the resistance wires:  

  100 MOhm or higher.

  - The resistance value of the heating element: Within -5/+10% of nominal 

   value.

  Enter the results into the warranty form.

3.

  It’s recommended to treat the sub floor with a primer so that mat can be  

easily fixed to the underlay. Apply the primer with a brush, and leave to 
dry. Do NOT apply a primer later on, after the heating cable mat has been 
installed, as this might dissolve the adhesive on the net.

  - MILLIMAT 100 W/m² can be installed on any type of stable and leveled 

  sub-floor.

  - MILLIMAT 150 W/m² must be installed on a non-combustible sub-floor 

  (leveled and stable) with minimum thickness 5 mm.

4. IMPORTANT!

  Please investigate if the cold lead attached to your heating mat/cable has 

got a hidden splice marked with -> SPLICE <-, or a manual splice identified 
as a bulge on the cable:

Manual Splice

Splice

Splice

SPLICE

** Cold Lead **

Hidden/integrated Splice

Manual Splice

  Irrespective of SPLICE type, the SPLICE has to be placed embedded into the 

heated floor, and NOT inside the wall or other non-heated area:

  Install and adjust the MILLIMAT by rolling out the mat on the sub-floor. 

Beware! When making adjustments: Do not cut the cable, only the net. 
MILLIMAT is self-adhesive, and is fixed by applying a light pressure. When 
cutting and adjusting the mat, ensure that the cables are kept at the same 
distance from each other as the cables on the mat itself. Make sure that the 
splice (the connection between cold and hot part of the cable) is placed so 
the cold lead reaches the thermostat, and that the splice itself is placed in the 
floor and not inside the wall. 

The end seal shall never be placed under permanent installa-

tions.

  If other cables (which are not a part of the heating cable installation) are 

embedded in the heated floor these must be placed at least 3 cm (1,2 
inches) away from any heating cable. The current-carrying capacity of these 
cables must be adjusted due to the heated surroundings. If a floor sensor is 
used it must be connected at equal distance between two cable strands. It’s 
recommended to install the floor sensor inside a tube, making it possible to 
replace it in the future.

5.

  Measure the ground insulation and conductor resistance again before 

pouring the adhesive/screed/mortar/concrete. Enter the results into the 
warranty form. Avoid stepping on the cable and be careful during further 
works and embedding. Remember that while the cable is installed but not 
yet embedded, it is exposed and somewhat vulnerable.

6.

  When embedding, use cement-based tile adhesive, thinset mortar, screed or 

concrete, with good heat conductivity suitable for heated floors. During the 
pouring of the floor, the heating cable must be protected against potential 
mechanical damage, e.g. from concrete truck hose, buckets, tools etc. 

The following requirements to heat conductivity must be met:

  • For traditional cement based mortars the minimum requirement is 1.0 W/mK. 
  • For screeds and other special mortars, the minimum requirement is  

  0.6 W/mK with a maximum of 3 cm. molding thickness. For thicker floors, 
  the requirement is the same as for traditional cement based mortars. 

  The heating cable must be embedded with minimum 5 mm (0,2 inches) 

concrete above the cable when the top floor covering is tile or stone. The 
minimum thickness above the cable is 10 mm when the top floor covering is 
vinyl, linoleum, carpet, engineered wood or other. As a minimum, the  
MILLIMAT must be covered entirely by the adhesive/screed/mortar/con-
crete, but a thicker layer might be required to ensure mechanical floor stabil-
ity. 

Use machinery / a power tool to mix well and pour shortly 

after mixing.

 Follow the guidelines given by the manufacturer and ensure 

that the MILLIMAT is fully embedded. Any additive/filler (e.g. metal fibers) 
must be of such a nature that it cannot inflict any damage on the cable.

  After pouring, compact well to avoid air pockets and a porous slab. The 

concrete must embed the cable entirely to ensure sufficient heat conductivity 
from the cable to its surroundings. Good heat conductivity is important for 
the function of the floor, but also to prevent excessive temperatures. Some 
concrete types can be mixed with reduced amounts of water as specified 
by the vendor. In these cases, pay special attention to the mixing and the 
compacting as these floors easily become porous and thereby thermally 
insulating. 

  The heating cable is not to be used before the concrete has dried and cured 

naturally. This can take up to 6-8 weeks. In renovation projects special 
screeds for thin floors are often used, and these may have a shorter curing 
period. Please consult the instructions/guide provided by the vendor of the 
concrete.

7.

  Install the top floor 

Area power specific rules 

MILLIMAT 100 W/m² can be installed beneath most types of floor covering. 
That includes wood, laminate, parquet, vinyl, tiles, slate, stone, marble, etc.*