​​What method of underfloor heating does Heatwell use?

Heatwell installs both of our own Pro Series and Gold Series of underfloor heating cable.  The heating cable is attached to the sub-floor, a fibreglass mat is placed over the top, a self-levelling compound or screed is poured over the top.  The result is a heating element that is encased and protected.

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The method of fibreglass mesh and screed over underfloor heating cable is very effective for carpet.  The underfloor cable is basically locked into a reinforced concrete structure.  Heavy furniture or areas of high traffic will not damage the underfloor heating cable.

 

Heatwell specialises in electrical underfloor heating systems, and we do not install in-concrete or hydro underfloor heating.

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Does Heatwell use foil underfloor heating mat or thermopads under carpet?

No.  Heatwell does not recommend foil underfloor heating mats or thermopads.  They should not be installed in high traffic areas or under heavy furniture as the heating cable is likely to be crushed.  A crushed foil mat or thermopad creates a fire risk very similar to how a damaged electric blanket creates a fire risk.

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Should underfloor heating be installed under a bed?

Heatwell highly recommended installing underfloor heating under where a bed is going to be located.  The underfloor heating will help dry out the mattress in the winter months.  With Heatwells' fibreglass mesh and screed system, a heavy bed will not damage the heating cable.

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How much height to the floor does the Heatwell method add?

Installing underfloor heating cable, with mesh and floor leveling compound over the top, adds approximately 4mm to the height of the floor.  Budget for 5mm to be safe.

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How much underfloor heating should be used under carpet?

Heatwell recommends that 100W per square metre be installed under carpet.  However, more heating is always better than less.  If the area is relatively small like a bedroom, please consider installing 120W per square metre.

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Is there a maximum or minimum amount of Watts that can be installed per square metre?

Yes.  The maximum heating per square meter should not exceed 180W.  180W installed under carpet is way too much.

Heatwell recommends a maximum of 120W per square metre under carpet.  The minimum underfloor heating per square metre is 100W.  There will be cold patches as the spacing between the underfloor heating cables is too far when less than 100W per square metre is installed.

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Can an underfloor heating cable be cut to size?

No! Unlike most other electrical cable, underfloor heating cable cannot be cut to length.  All underfloor heating cables come premade to lengths that suit the size in Watt being installed.  The underfloor heating cable comes with cold tails attached and is sealed to be waterproof.  A damaged underfloor heating cable can be fixed, however, that is a job for a registered electrician.  Cutting the underfloor heating cable will void warranty.

Make sure that you buy the right size of underfloor heating cable.  Heatwell has a measuring app available that can help.

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When is the under-carpet heating installed?

Underfloor heating under carpet is done just before the carpet is laid.  All painting and other prep work should already be complete.

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Can any type of carpet, carpet tiles, or carpet underlay be used?

Unfortunately not.  You must be very careful of the thermal factor of your carpet, carpet tiles, and carpet underlay.  With products like thick wool carpet, there is a natural level of insulation that does not work well with under-carpet heating.  Some types of underlay are designed with insulation in mind.  Please ask your carpet specialist if your choice of carpet or carpet tile is suitable for underfloor heating.

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Can under-carpet heating be installed over the top of any type of floor?

Underfloor heating can be installed directly over concrete as long as there are no cracks, holes, or sharp protrusions.  Underfloor heating can also be installed over tile and slate underlay, insulation board, or acoustic mat.  Installation over the top of particle board or plywood is not recommended.  Expansion and contraction of particle board or plywood is a certainty in NZ’s conditions.  Expansion and contraction risks cutting the electrical element where the flooring butts together.

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How should particle board or plywood be prepped?

There are three excellent options.  The most common is laying tile and slate underlay.
Another option is to lay 6mm insulation sheeting. Infinity from Tile Max is an example.  Insulation sheeting has the big advantage of improving the efficiency of the underfloor heating and will save you money in the long run.
The third option is to incorporate an anti-fracture rubber-based system into your waterproofing. This option is probably the most expensive, however, it adds the least to the floor height.  Please check with the manufacturer to ensure that self levelling compound can be installed over the product.

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What condition does the floor need to be in prior to the under-carpet heating installation?

All floors need to be clean, free of dust, and free of paint.  They also need to be free of any cracks, holes or sharp protrusions.
A floor that is being renovated needs to have all the remains of the previous flooring removed.  Including glue from fixing down carpet or underlay.

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Is there any wall prep required?

Yes.  The thermostat controller will need to be mounted on the wall.  The cold tails that are attached to both ends of the heating element must come up from the floor to the thermostat flush box.  25mm holes need to be drilled through the wall nogs.  A 50mm wide and 25mm deep section must be checked out the wall base plate.  A draw wire from the thermostat flush box down to the bottom plate is essential.  The flush box for the thermostat can be installed either vertically or horizontally.  Heatwell has thermostat options for both.

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What does the Electrician need to know?

A 900W element draws 3.91amps and is 58.78ohms in total.  Any heating element 1000W or above needs a dedicated RCD, with its own circuit back to the board.  All of Heatwells' thermostats have a 16amp maximum capacity.  If there is more than one underfloor heating cable using a single thermostat, the total amps must be taken into account.

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Can an Electrician repair a damaged cable?

Yes.  An underfloor heating cable has an inner and outer core.  The inner core is the heating wires.  The outer core is the earth wire.  The underfloor heating cable needs to be cut at the damage.  The heating cable will need to be crimped together then sealed with waterproof electrical heat shrink (Raychem).  The earth wire will then need to be crimped together.  A final layer of waterproof electrical heat shrink to seal the whole repair.  The heating cable and the earth cable cannot touch or be joined together.  Please note that a significant thickness will be added to the underfloor heating cable.  You will need to check out an area under the join for the repaired wire to sit flush with the rest of the cable.

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What does the Carpet Layer need to know?

Please don’t drop anything sharp or heavy on the screeded surface.  Be very careful of your carpet gripper!  Where the floor heating goes up the wall to the thermostat is the danger point.  Putting a nail through the cable will ruin everyone’s day!