​​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.  The final flooring installer will love the flat level surface.

 

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

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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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Are are vinyl, LVP, and Lino products the same?

No.  In fact you must be very careful with lino planks or LVP that do not clip together.  Cheaper products have not be designed to take expansion and contraction into account.  Expansion and contraction is not good over underfloor heating as cracks between planks will develop over time.  Quality vinyl planks and LVP has used materials that minimise expansion and contraction.  Full sheets of vinyl or lino are in fine.  The full sheets are still likely expand and contract, however no cracks will develop. 

It's always best to ask your flooring specialist if your chosen final flooring is suitable over underfloor heating.

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How much underfloor heating should be used under vinyl, LVP, and Lino products?

Heatwell recommends that 120W per square metre be installed under under vinyl, LVP, and lino.

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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 vinyl, LVP, and lino is too much.  The minimum heating per square meter should be 100W per square metre.  100W installed under vinyl, LVP, and lino is enough if the room is large.  Heatwell recommends a minimum of 100W and a maximum of 120W per square metre under vinyl, LVP, and lino.

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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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How long does the self-levelling compound (screed) take to dry?

Please allow 24 hours. In cold conditions, drying can take more than 24 hours. If you are worried about about drying time, a heater in the area will help. Tiling or waterproofing cannot be done if the floor is not fully dry.

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When is underfloor heating installed under vinyl, LVP, and lino?

Underfloor heating is done just before the final flooring product is laid.  Installation of the final flooring product should not be done until the screed is fully dry.

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​Can underfloor heating be installed under vinyl, LVP, and lino 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.
Installation over the top of particle board or plywood however 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 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 undervinyl, LVP, and lino 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.

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Is there any wall prep required?

Yes.  We need a flush box for the thermostat / controller.  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 of 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 full 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 final flooring installer need to know?

Please don’t drop anything sharp or heavy on the screeded surface.  The installer needs to remember to allow a small gap between the edge of the flooring and the wall to allow for expansion and contraction.