The ELEKTRA VCD17 electric underfloor heating cable is a durable and efficient solution that brings unparalleled thermal comfort. While the cable is guaranteed to last 20 years under screed, its installation is surprisingly simple and can be done by anyone with a little skill!
This guide will help you through all the steps from planning to pouring the screed, ensuring the installation is correct.
⚠️ Attention: Although you can carry out the cable installation yourself, the final connection to the electrical network (to the thermostat) must be carried out by a certified electrician.
Chapter 1: Preparation and Planning (Do Not Skip This!)
Before cutting the first fixing strip, ensure you have everything ready:
1. Check the Substrate
The surface on which you will mount the cable (the concrete slab) must be clean, dry, and thermally insulated (thermal insulation beneath the cable is crucial for energy efficiency!).
2. Define the Installation Area
The cable should NOT be installed under:
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Fixed sanitary objects (bathtub, WC bowl).
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Heavy and permanent furniture (massive wardrobes, fixed kitchens without legs).
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The area directly beneath the thermostat box.
3. Calculate the Spacing Between Runs
The VCD17 cable has a power output of 17 W/m, making it ideal for primary heating. To achieve the optimal power density per square meter (W/square meter), you must determine the distance between the cable runs (the installation pitch).
If you wish to install a power density (e.g., 150 W/square meter for a bathroom, or 100 W/square meter for supplementary heating), use this simple formula:
Spacing (cm) = [Cable Power (17 W/m) X 100] / Desired Power Density (W/square meter)
Example 1 (170W/square meter): If you desire a power density of 170 W/square meter:
Spacing (cm) = [17 X 100] / 170 = 10 cm
Example 2 (150W/square meter): If you desire a power density of 150 W/square meter:
Spacing (cm) = [17 X 100] / 150 = ~11.3 cm
Chapter 2: Mounting the Cold Lead and Sensor
The VCD17 cable is twin-conductor and is powered from one end only – a huge advantage for installation!
Step 1: Mounting the Thermostat Box
Fix the electrical box to the wall, approximately 1.4 – 1.6 meters above the floor. The heating cable (cold lead) and the sensor will connect here.
Step 2: Routing the Cold Lead
The cold lead (the non-heating section, which is thicker) must run from the VCD17 cable directly into the thermostat box.
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Create a small groove in the wall/floor to hide the cable connection and the cold lead.
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The connection joint (the splice between the cold lead and the heating cable) must be completely integrated into the screed/mortar.
Step 3: Mounting the Floor Sensor
The temperature sensor must be installed in a protective conduit (PVC pipe) so that it can be replaced later if necessary.
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The sensor conduit must be positioned exactly halfway between two cable heating runs.
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The end of the sensor tube must be sealed to prevent screed from entering.
Chapter 3: The VCD17 Cable Installation
Step 4: Securing the Mounting Strips
Fix the metallic mounting strips directly onto the substrate (thermal insulation) using adhesive or screws. These strips have predefined slots to help you maintain the calculated distance (e.g., 10 cm).
Step 5: Laying the Cable
Begin laying out the VCD17 cable:
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Start from the connection joint, which exits the wall.
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Route the cable across the entire surface according to the plan, using the slots in the mounting strips.
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DO NOT cross the cable over itself.
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Ensure the VCD17 cable is at least 5 cm away from walls, pipes, or other hot objects.
Chapter 4: Testing and Finalization
This step is essential for validating the 20-year warranty!
Step 6: Testing the Cable (Mandatory!)
Before pouring the screed, measure the cable's resistance (Ohm) with a multimeter and check the insulation (M-Ohm) with a megohmmeter.
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Record the values obtained on the warranty certificate and ensure they fall within the tolerances specified by ELEKTRA.
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This test must be repeated after the screed has been poured!
Step 7: Covering with Screed or Mortar
You can now pour the screed (or use a self-leveling compound).
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Ensure the cable is completely covered (a layer of at least 3-5 cm of screed is usually ideal).
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Do not turn on the heating system immediately! Respect the screed drying time (usually 28 days) to avoid cracks.
Step 8: Final Connection
After the screed has dried, the certified electrician can perform the connection of the cold lead and sensor to the thermostat.
👏🏻Congratulations! You can now enjoy the pleasant and efficient warmth of your ELEKTRA VCD17 system.
