​​What method of underfloor heating does Heatwell use?

Heatwell installs both of its own Pro Series and Gold Series of underfloor heating cables.  The heating cable is attached to the sub-floor, a fibreglass mesh 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 self-levelling compound over the top, adds approximately 4mm to the height of the floor.  Budget for 5mm to be safe.

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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 been 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 use materials that minimise expansion and contraction.  Full sheets of vinyl or lino are 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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Is there a maximum temperature underfloor heating can be under vinyl, LVP and lino?

Yes.  Heatwells' maximum recommended temperature under vinyl, LVP, and lino is 27 degrees Celsius.  Anything over 27 degrees may result in delamination and discolouring.  Please check with your final flooring provider for underfloor heating recommendations.

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Can a maximum temperature of 27 degrees be set on a thermostat?

Yes.  Heatwells' HT4 and HT5 series of thermostats both have the capacity to set a maximum temperature that will not vary between manual and program modes.

 

Does vinyl, LVP or lino need to acclimatize before laying over underfloor heating?

Poor quality vinyl, LVP, or lino should never be used over underfloor heating.  Shrinkage, delamination and discoloration are a significant risk when using inferior product over underfloor heating.  High quality vinyl, LVP, and lino will be able to be laid without an acclimatization period.  However, the screed over the underfloor heating must be 100% dry.

You must talk to your final flooring provider about underfloor heating before you install.

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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 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.  Heatwell recommends a minimum of 100W and a maximum of 150W 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 drying time, a heater in the area will help. Vinyl, LVP, and lino 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.  Underfloor heating can also be installed over tile and slate underlay, insulation board, acoustic mat or self-levelling compound.  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 under vinyl, 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 removed from 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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Can underfloor heating be installed over existing tiles if installing vinyl, LVP, or lino?

Yes.  However, no tile can be loose or broken.  The tile surface will need to be ground to take any glaze off the tile, and will need to be primed before underfloor heating is installed.  However, installing over tiles is adding significant height to the floor.  Underfloor heating adds a minimum of 4mm and tiles add a minimum of 12mm.  Heatwell and any other installer would prefer that the old tiles are removed.

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Can underfloor heating be installed over existing vinyl, LVP, or lino?

No.  All existing vinyl, LVP or lino must be removed.  All glue and other remnants must be removed.  The subfloor must be striped back to its original condition.

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Can underfloor heating go under vinyl, LVP, and lino in a bathroom or laundry?

Yes.  However, waterproofing should be done after the underfloor heating has been screeded in.  Vinyl, LVP, and lino cannot be used in a shower.

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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 is needed 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 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.

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Does vinyl, LVP, or lino need to be fully adhered over underfloor heating?

If the product being used is a plank style system it will need to be glued to the floor.  Adhesive can be used as long as the underfloor heating cable is screed in.  Sheet vinyl or lino does not need to be glued to the floor.

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Does sheet vinyl or lino need a smoothing compound over the screed?

Yes.  A screeded surface will always have a few imperfections.  Sheet vinyl or lino will show those imperfections.