UNDERFLOOR HEATING MAT INSTALLATION GUIDE

 

Heating Cable Description

Underfloor Heating World (Living Heat) Heating cables are manufactured to comply with all EC European standards. All our Under floor heating conductors are made using a PTFE outer insulation, high tensile film screen, fully braided earth shield with a high temperature PVC (melt point 105°C) outer protective jacket; to form a high specification conductor heating cable. Heating cables are totally waterproof and incorporate an earth screen, making them perfectly suited for installations in wet areas. The resulting heating cable is extremely safe, durable and robust, with a thin profile of 2.2mm (single core) and 3mm duel core.

Heating cables are attached to a 500mm open weave mesh mat backing at preset factory spacing, to produce the Standard Output of 150w/m2 or 200w/m2 heating mats (150W/m2) and are ideally suited for the majority of underfloor heating applications. 200w/m2 units are ideal for use in high heat loss areas such as conservatories. Both 150w/m2 and 200w/m2 units are suitable for use as primary heat sources assuming a minimum of 70% floor coverage is achieved and suitable levels of insulation are installed.

Measuring Up Under Floor Heating Mats

It is important to measure the room correctly and avoid all permanent fixtures such as baths, showers, kitchen and bedroom units. It is important to avoid thermally blocking the heated area as this will result in localised heat build-up and possible subsequent damage to the floor covering.
From the total area you are planning to heat deduct a further 10% to make an allowance for the perimeter.

For greater areas individual cable lengths can be joined in any configuration and connected in parallel. A contactor can be used where a single thermostat is required to control a total area of underfloor heating exceeding a 16amps. Alternatively consider the use of an additional thermostat. Underfloor Heating World, (Living Heat) thermostats are all rated at 16amps.
NOTE: Amp loading is based on 230 Volts If in any doubt contact for advice

Planning The Installation of Floor Heating Mats

The diagram below illustrates a kitchen floor 5m x 3.2m, which equates to a total area of 16m2. However, due to the fixed units and island the total usable area available to heat is reduced to 11.3m2. After deducting a further 10% perimeter allowance, this leaves a total heated area of 10.2m2. With this information the size unit selected should be a 10m2 (0.5x20m) units. The mat layout below shows a duel core mat, requiring connection to the electricity supply at one end only. The advantage of the duel core mat is by removing the need to design the layout to get the cable back to the original start point. The advantage of the single core is it is cheaper to purchase and also is thinner than the duel core unit so is easier to tile over and also requires less adhesive to cover.

 

Installation of Large Areas Using a Combination of 2 Heating Mats

Illustrated below is a 19m2 conservatory requiring a primary heating source. High output underfloor heating world (Living Heat), 200W/m2 mats have been selected for the installation.

After making an adjustment for the conservatory corners of 1m2, a 10% standard perimeter allowance has been deducted to give a total heated area of 17.1m2: As 12m2 is the largest single mat size a 17m2 system is required which can be made up by combining 2 separate heating mats. A discount is provided when purchasing multiple mats.

Using the larger of the two heating mats, run this out from the termination point to the opposite end of the room: check the remaining floor area will accommodate the additional heating mat. Lay the additional heating mat and where necessary cut the mat backing to allow the floor heating cable to be run around fixed units, odd shapes, corners and previously laid matting. Remember; never overlap the heating mats as this will cause localised overheating, leading to eventual failure and invalidation of the manufacturer’s guarantee.

The thermostat sensor must be positioned centrally between the heating cable loops – see the Thermostat and Floor Sensor section below.

Floor Preparation

All floors should be suitably prepared prior to laying the heating mats:

Concrete sub-floors

If the sub-floor is a new concrete floor it should be allowed to cure naturally – as a guideline you should allow 1 week per 25mm but this is dependent upon weather conditions. If the finished concrete floor is not level then a thin layer of levelling compound should be applied to give a smooth and level surface.

Wooden sub-floors

Timber floors should be clean and level. Where necessary (especially if laying tiles on top of the underfloor heating), suitable plywood over-boarding should be laid, in line with the Tiling Federation recommendations.

Primer/Sealer

The use of a suitable Primer/Sealer is recommended by adhesive manufacturers on both concrete and wooden sub-floors to seal the porous sub-floor, prior to applying adhesives or levelling compounds. For more information on Underfloor Heating World (Living Heat), flexible tile adhesives, flexible grouts and flexible levelling compounds and primers please do not hesitate to contact ourselves.

Installation of Underfloor Heating Thermal Insulation

Where any underfloor heating is installed, heat energy will travel in both directions; down as well as up. Cement floors act as a heat sink absorbing this energy, creating a large drag on the performance of the flooring above. A high quality thermal barrier between the heat source and the sub-floor will significantly improve the performance of your floor heating, speeding up the initial warm up times and saving money on electricity costs. Underflooor Heating World (living Heat) offer a 6mm, 10mm and 20mm hard insulation boards for use under tile and stone floors. Please see insulations for more information or contact Underfloor Heating World (Living Heat)

Cutting and Shaping Under Floor Heating Mats

NOTE: Never cut the cable, this will invalidate the manufacturer’s guarantee: only the mat backing mesh can be cut. The heating cable should be no closer than 50mm from the walls and any other fixed obstruction. NEVER bury or try to hide the cable, if necessary start again. If you have ordered the wrong size of mat contact Under floor Heating World (Living Heat) and provided that the mat and cable have not been cut, laid or damaged in anyway, then it can be exchanged. Before, during and after you must test the circuit using an ohmmeter to check the resistance readings and mark these down for later comparison. The correct ohms reading can be found on the information label on the heating mat / box.
Finally, to prevent potential damage to the heating cable, avoid excess traffic over the area until the final flooring is laid. Please see diagram below showing the cutting and laying of a heating mat.

Laying Underfloor Heating Mats

Having now planned the layout of the heating mat to obtain the best fit within the floor area, the mat now requires to be stuck down to the underfloor heating world (living Heat) hard insulation boards if they are installed or wood/cement sub-floor if no insulation has been laid. To hold the mat firmly to the insulation or sub-floor, sticky strips have been manufactured onto the underside of the mat backing and can be seen with a smooth protective layer. Progressively lay the mat into the planned heated area, peeling the protective strips to expose the tacky surface of the tape, firming pressing the mat down as you go.

Thermostats and Floor Sensor

It is normal practice to site the floor heating thermostat within the room to be heated, however for bathrooms the thermostat is required to be sited outside.
The first 3 metres of black connection cables can be cut as required. The red/blue heating cable must never be cut or shortened.

If connecting your heating mats directly through a 16 amp thermostat: A 16amp thermostat will control a maximum wattage of 3600 watts. The maximum equivalent combination heating mats in the underfloor heating world (Living Heat) 150 range is (22m2)
The maximum equivalent combination heating mats in the underfloor heating world (Living Heat) 200 range is (17m2)

Contactors

A Contactor can be used where a single thermostat is required to control a total area of underfloor heating in excess of 3600 watts or a total loading exceeding 16 amps. The Floor Heating Contactor will control up to a maximum of 22,000 watts or 95 amps total loading: The total maximum area depends upon what size / rated contactor is installed.

Positioning The Floor Sensor

Having determined the size of the area to be heated and the correct size heating mat required; the next step in the installation process is to position the floor sensor correctly. Following the instructions provided with the thermostat, the probe should be fitted onto the floor, taped over the end (to protect the sensor from ingestion from tile adhesive or levelling compound) fixed into position with gaffer type tape and connected to the thermostat. The end of the probe should be directly between two pre spaced heating wires. Please see floor probe positioning below.

Heating – Power Connection and Testing

To comply with current Part P Electrical Safety Regulations, it is now a requirement to connect your underfloor system via a fused spur (to isolate the system). The power supply should be from a safety contact breaker (RCD) to the thermostat – a qualified electrician would be able to advise you

Tiling Over Underfloor Heating

Once the heating mats/cables are laid, suitable protection boards should be used to prevent any possible damage during the tiling phase. A good quality rapid setting flexible tile adhesive should be laid evenly and spread in the same direction as the cables are running, in order to fully encapsulate the heating cable, leaving no air spaces. NOTE: To avoid any potential damage to the heating cables that may be caused during tiling extra care should be taken not to damage the heating cables. Regularly checking the heating system is advisable during this stage of the instillation. An alternative method of installation would be to pour a thin layer of flexible, self-levelling compound (sometimes referred to as latex) to cover the heating cable to give a level surface prior to laying the tile adhesive. Once the levelling compound has dried (12 – 24 hours) tiles can be laid as normal using a good quality flexible tile adhesive.

Switching on Your Heating System

Before switching on the under floor heating system allow a minimum of 3 days for natural drying of the tile adhesive and grout or levelling compound. It is recommended to initially operate the system for 1 hour, gradually increasing daily operation by a further 1 hour per day to full continuous use after 6 - 7 days.

Please note that all electric underfloor heating systems should be installed and connected to conform to current electrical legislation. If in doubt, A suitably qualified electrician should be consulted prior to installing your heating system. A qualified electrician should make the final connection of the thermostat and commission the system: the installation will require a certificate to be issued by the electrician to conform to current electrical legislation and to validate your manufacturer’s guarantee.

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