Electric Underfloor Heating for Nailed Hardwood

While WarmlyYours electric radiant floor heating systems are typically installed by your floor covering contractor, a licensed electrician is recommended for the final thermostat hook-up. With every quote, we provide an Installation Plan layout, together with an electrical plan that has all the info required for the electrician.

You can use the Instant Quote Tool, which gives you many options for your floor heating coverage. Use this interactive tool to design your room online and receive an instant quotation with product recommendations, rough-in and installation kits, cost of your control, etc. Planning your floor heating project is made easy when using our Instant Quote Tool.

Send us your floor plan or fax it to (800) 408-1100 and we will send you a quote, product recommendation and a free custom installation plan for your project.

Our electric radiant floor heating systems have withstood rigorous safety testing and earned the UL listing. They produce much less EMF than common household appliances like your TV or vacuum cleaner. The EPRI (Electric Power Research Institute) tests all electrical devices and publishes the data. Many common household appliances are tested at a distance of 6 inches. The test results indicate that on average, the EMF emitted for the following appliances, measured in Milligauss (mG) units, is:

Vacuum Cleaner: 300 mG

Microwave: 200 mG

Portable Heater: 100 mG

Dishwasher: 20 mG

Washing Machine: 20 mG

WarmlyYours TempZone™ (Twin): 1.8 mG

The floor heating systems are offered in both 120 volt and 240 volt for the North American market. A 208 volt breaker panel can also accommodate our 240 volt floor heating system. It is important to note that the energy consumption will be the same: a 240 volt system will not cost more to operate than a 120 volt system. You are billed in kilowatts, and the 120 volt and 240 volt systems use the same amount of kilowatts. WarmlyYours often specifies a 120 volt system in smaller projects while a 240 volt system is typically recommended for larger projects (120 square feet of electric floor heating coverage or more). The benefit of switching to a 240 volt system is the reduction in amperage. Our programmable thermostat can control a radiant floor system up to 15 amps. The 120 volt system will reach 15 amps at 120 square feet of electric floor heating coverage. However, the 240 volt system will reach 15 amps at 240 square feet of electric floor heating coverage, allowing a much larger system to be connected to the thermostat. For installations over 240 square feet, a relay contactor or power modules are needed.

Yes. Unlike the heating cable for electric floor heating, the cold lead wires can be trimmed.

Sunrooms can be very cold during the winter months. While a furnace may push some warm air into the room, the large number of windows, exterior walls, and other causes of heat loss in a sunroom will typically keep it from having a comfortable temperature level. Floor heating and radiant panels will add radiant heat, which the human body absorbs faster than other forms of heat, to the room so that it feels warm even at lower temperatures.

To prevent any melting, ensure that the heating wire is at least 4” from the toilet wax ring.

Yes, but any furniture that may trap heat, such as pieces with an enclosed bottom, should be avoided. Furniture on legs with a clearance of at least 3" is permissible.

When installing electric floor heating over a concrete slab, an insulating underlayment like ThermalSheet is highly recommended to ensure efficient operation, faster heating times and warmer floor temperatures.

The perfect room or floor temperature is always going to be a personal preference. However, we do see that our customers will usually set their floor temperature to somewhere in the 80°F to 84°F range.

When WarmlyYours electric floor heating systems are being installed on a concrete slab, we strongly recommend adding a layer of insulation over the slab prior to installing the system. While our electric floor heating provides up to 25% more heating power per square foot than many of our competitors, the slab will always act as a "heat sink." Some of the heat that would otherwise be transferred to the flooring surface will remain in the slab, causing the floor’s surface temperature to be considerably lower. This is true with any electric radiant floor heating system.

When installed on top of a concrete slab without insulation, it is generally accepted that electric floor heating will take the chill away from the floor and provide a small amount of warmth. Adding insulation on top of the slab and beneath any electric radiant floor heating system will allow a greater percentage of the heat generated to transfer to the flooring surface. This results in greater efficiency and therefore faster warm up times, higher expected surface temperatures and lower energy usage. The floor will have the capacity to warm to a comfortable temperature, and in some cases can be employed as the primary heat source for that room.

The recommended types of insulation are natural cork, insulated tile backer boards and insulated underlayment, such as ThermalSheet™ synthetic cork.

The subfloor will need to be prepared as per the instructions of the self-leveling cement (SLC) used. Please note that most self-leveling products require the use of a primer as specified by the SLC company.

Electric-resistance heating cables and systems have no polarity. This includes all current WarmlyYours heating elements.

No, it is recommended that floor heating only be installed in the areas that you will walk on. Heat can become trapped if installed under objects that do not offer enough clearance for air to circulate (such as a washer or dryer).

Since most Luxury Vinyl Tile (LVT) manufacturer's set a maximum temperature for radiant floor heating, the system should have little to no effect on the rubber/cork backing.

Pre-attached backing can act as an insulating layer though, meaning it can prevent the radiant heating from efficiently directing heat up through the floor. Please check with the manufacturer for the r-value of the product. Look for an assembled plank with an r-value of less than 1. The lower the r-value, the better!

Yes, in most cases, an electric floor heating system can be effective as a primary heat source. However, our TempZone™ and Environ™ systems are most commonly used as a secondary heat source, providing floor-to-ceiling radiant heat to any room in your home where you desire more warmth and comfort.

If you are considering electric floor heating for an addition to your home, such as a sunroom where you have no other source of heat, WarmlyYours offers an innovative online tool which calculates approximate heat loss. This tool can help you to determine if a WarmlyYours’ electric radiant floor heating system will provide your desired comfort temperature throughout the year. You can access the Heat Loss Calculator or you can call us at (800) 875-5285 and a Customer Service Representative will make the calculation for you.

Supplemental heat can be addressed by changing the spacing on cable installs. Floor location in the house is very important when considering adding supplemental heating to a floor. For example: If heating a second story floor, over a heated space, cable at 4" spacing can be used. The same type of heating over an unheated space would probably be done with TempZone Flex Rolls or TempZone Cable at 3" spacing. All heating is considered supplemental unless a heat loss calculation is done.

Yes, our TempZone Heating Products can be used for heating luxury vinyl tile or luxury vinyl planks in any indoor application.

Always check with the flooring manufacturer to see what they will cover when it comes to floor heating. In most cases there will be a floor temperature limit - this can be programmed into a programmable or smart thermostat. Check for installation instructions and requirements before adding floor heating.

The breaker and wire sizes are selected based on the total amperage of the WarmlyYours heating system connected to a single thermostat. This information is on the WarmlyYours heating system's installation plan, electrical plan, or UL label. Based on guidelines from the National Electrical Code: loads up to 16 Amps may utilize 12 gauge wire with a 20-Amp breaker, and loads up to 12 Amps - 14 gauge wire with a 15-Amp breaker. Local code and/or other factors may change these guidelines.

WarmlyYours’ 25-Year No Nonsense™ Warranty is the most comprehensive warranty in the industry. In the event of a defect, we cover not only the repair or replacement of the TempZone™ system, but ALSO any labor costs AND flooring materials required to perform the repair. We do not cover the cost of flooring that needs to be replaced in the event of a repair necessitated due to damage. If a product is damaged by a power surge, that would not be covered by our warranty

Yes. The WarmlyYours TempZone™ floor heating system has withstood rigorous safety testing by the Underwriter's Laboratory and has received UL listing for the U.S. as well cUL certification for Canada. WarmlyYours offers thermostats that carry the CSA Mark and the UL listing, which certifies that the product has been tested under extreme conditions and meets applicable standards for safety and/or performance in the U.S. and Canada. All WarmlyYours thermostats contain a Ground Fault Circuit Interrupter (GFCI) which provides fail-safe protection against an electrical shock.

Yes, using a square-notch trowel (1/4” x 1/4” or larger), apply a layer of thinset to the subfloor area which will later be covered by the WarmlyYours TempZone™ Flex Roll, Easy Mat or Custom Mat.

WarmlyYours nSpiration controls are equipped with an in-floor sensor to precisely control the floor's temperature to comply with the wood manufacturer's temperature recommendation.

This is stated in the Installation Manual of the LVT product when purchased. On average, this maximum temperature will fall between 80°F and 83°F. This number can then be used to program the thermostat during setup to set the floor's maximum temperature.

No, most in-floor heating is designed to be added to new flooring. If you do have existing wood floors you would like to add radiant heating to - it is possible to do so with an under-joist heating system. 

Yes, Luxury Vinyl Tile (LVT) is typically installed over the embedded heating element using self-leveling cement (SLC). Many people choose to use SLC when installing tile over floor heating.

We do not suggest using thinset to encase the heating wires with LVT, as it is very difficult to get thinset completely flat.

The TempZone™ twin conductor cable present in our TempZone™ products is comprised of a double-insulated, coaxial heating cable. The total thickness of the system can be between ⅛” and 5/32” thick and will not noticeably affect the height of your installed flooring. The heating system is encased in 3/8" of modified thinset or Self leveling underlayment. You simply use that 3/8" layer throughout the space, eliminating any need for fillers.

Bathrooms designed with shower and floor heating will include only one thermostat by default. But it is possible to design with a thermostat for each zone if desired. Installing a separate thermostat for the shower area can help reduce cost and energy usage. This also allows you to heat the bathroom floor alone for everyday use and only heat the shower area when needed.

No. A bathroom floor would be installed in the same way. Our TempZone floor heating systems are wet-location listed and ideal for bathroom floors.

For best results, we recommend a 1”- 1.5” maximum distance between the heating cable and the top of the floor. Nailed down hardwood will require sleepers to run the cable safely between board nails. Be sure to use 3/8" to 3/4" of self-leveling cement to embed the heating element.

If the flooring manufacturer has a warranty for electric floor heating, it should not be adversely affected by shrinkage, expansion, or warping. Again, it will depend on the brand and construction of the product. Some manufacturers may place limitations on the maximum floor heating temperature. To minimize expansion and contraction, some Luxury Vinyl Tile companies require heating the flooring to a continuous heating level with "setback" temperatures (lower temperature settings during the day and overnight) kept to a minimum.

While radiant heating can affect the expansion and contraction of the floor, the most overlooked and important factor is the relative humidity in the space, so a humidifier or dehumidifier may be needed.

Floor heating will typically add the most heat to supplement an existing heating source and it will not take any extra space since it is embedded in the floor. If you are not remodeling your floors but have some open wall space, you should mount a radiant panel. For the most effective results, install the panel so that it points toward the area where you will spend most of the time.

The actual cost of operating your floor heating system will vary depending upon a number of factors including the cost of electricity in your area and the length of time you run your system. The WarmlyYours TempZone™ Flex Roll electric floor heating system, for example, uses 15 watts per square foot. Based on a national average electricity rate of $.10/kW/hr, the approximate operating cost of an average bathroom using this system, measuring 8' x 10' would be between $.16 - $.21 cents a day. This cost is based on running your system a full 8 hours per day. Try our Operating Cost Calculator for a quick estimate.

No. Never cut the heating cable. The floor heating cable is designed with a very specific resistance in order to consistently maintain heating at the chosen wattage per square foot. Trimming the heating cable would lower the resistance of the cable causing the system to overheat. Adding heating cable to the system would raise the resistance and the system would not heat properly.

Waterproofing for the room is in the layer above the floor heating system. The layers for waterproofing this type of floor are:

• subfloor
• thinset
• uncoupling membrane
• tempzone heating cable
• waterproofing tape for seams and corners
• thinset or self leveling cement
• tile floor

The most important factor for the wood floor chosen is structural stability.

According to the USDA Forest Service, this list shows most dimensionally stable to least: 

• Mesquite 
• Australian Cypress 
• Teak 
• Santos Mahogany
• American Cherry
• South Yellow Pine 
• Douglas Fir 
• American Walnut 
• Brazilian Cherry 
• Hard Maple 
• Red Oak 
• True Hickory
• American Beech

Engineered is the most structurally stable compared to natural hardwood, so it will work the best with floor heating.
If you do want to go with Hardwood, quartersawn or riftsawn narrow planks are the most structurally stable and would work best for this application.

Overall the most important factor for the room is relative humidity. Keeping a consistent humidity and temperature in the home will help wood floors last for many years to come.

We suggest removing SPC or WPC flooring before installing the floor heating system over it if possible. If that is not practical, use an underlayment designed specifically for covering these types of floors. Radiant heating can be used with many types of these floors, but check with the flooring manufacturer to confirm that it can be paired with these types of systems.

The shower floor heating kits can be tied into floor heating for the rest of the bathroom - allowing for one thermostat to control both areas as long as both areas are using less than 15 amps. When designing installation plans, we design with only one thermostat by default. If you prefer two separate thermostats, it might be a good idea, since the shower floor application is usually thicker and takes longer to heat. Be sure to let us know when discussing your quote with our team.

Yes. In addition to TempZone™ and Slab Heat, we also have specially sized Shower and Bench mats designed specifically for shower installation. They are all wet location listed for radiant floor heating in a shower.

TempZone™ is an electric floor heating system that operates like an electric blanket for your floors. TempZone™ is covered in thin-set or Self-Leveling Underlayment, and is installed over the top of your subfloor and beneath your flooring. The system provides a warm, even temperature across your floor, generating floor-to-ceiling radiant warmth to transform these naturally cold surfaces into warm floors. Ideal for kitchens, bathrooms or any room in your home where you would enjoy radiant warmth and comfort, the TempZone™ floor heating system is easy to install, operate and maintain.

Our TempZone electric floor heating products are waterproof and wet location listed.

Make sure any cracks or raised edges are sanded down before installation. Seal and patch cracks where possible. If needed, pour a layer of self-leveling cement to make sure surface is level and flat. Then proceed with instructions to install desired floor heating system and flooring.


It is strongly recommended that an insulating underlayment be installed between the slab and heating element to prevent heat loss.

We suggest the heating product be embedded in a minimum of 3/8" of self-leveling cement (SLC). Always check with the manufacturer for specific recommendations.

LVT (Luxury Vinyl Tile), WPC (Wood Plastic Composite), and Solid Core all fall into the category of "vinyl flooring." These vinyl flooring types can be rated for floor heating, but the application will completely depend on the manufacturer's guidelines.
Please look in the installation manual and warranty documents of the LVT, WPC, and Solid Core flooring product that you are interested in to see if and what types of heating are allowed.

As for a list of manufacturers of LVT, WPC, and Solid Core products providing a warranty for their products with radiant heat -- many do provide a warranty for their products when properly installed with floor heating. The list of these is ever-changing, so please be sure to check with the flooring manufacturer for current recommendations.

Yes, with our programmable thermostats, you can choose which days and times the floor heating turns on for your comfort. With a Smart thermostat, you can also control these options from your phone while away from home.

We usually recommend that you have an individual thermostat for each room. However, if it's an open floor plan and your local electrical code allows you to have one controller for the whole area, then it's definitely possible to have it all controlled from one thermostat.

The mats provide between 12 and 15 watts per sq. ft. (depending on room size). They are designed to distribute heat evenly for full room coverage. 

No, TempZone™ Custom Mats provide the easiest installation with no cut and turns required as they are specifically designed and built based on the dimensions of your project that you've provided to us. Prior to installation, dry-fit your mat to make sure it fits correctly. If there are any issues, call WarmlyYours at 1-800-875-5285. 

We recommend verifying 3 things with the manufacturer of the flooring product to be heated;

1.) Is the flooring product compatible with electric floor heating?

2.) What is the maximum temperature the flooring product can withstand?

3.) What is the temperature set back recommendation of the flooring product?

82°F - 85°F is the most common comfortable warm temperature of the floor.

The smallest TempZone Easy Mat is 3' x 2', which is great for heating the area in front of a toilet or shower.

When waterproofing a curbless shower, most guidelines require a continuous surface, created by a bonded waterproof membrane, on the floor and walls of the shower itself. The waterproofing should extend outside the shower enclosure for at least one foot beyond the highest point of the floor. Additional waterproofing outside the shower is suggested as a consideration, but is not required.

Heat will spread laterally about 1" to 1.5" from the end of the heating elements. 

An electric underfloor heating system doesn't need to be left on all the time. The system can be completely turned off or set back to a lower temperature when not in use. If you have a programmable floor heating thermostat, then the system can also be set to operate only during specific times.

Everyone has their own comfortable temperature setting, but we typically find that our customers use their thermostats to set the "floor temperature" of the system in the 78°F - 84°F range.

Yes, sunrooms can be used in the winter, just activate your floor heating or radiant panel and turn your sunroom into a 4-season room. You will notice a tremendous difference in the room comfort, especially with the thermostat set to maintain a desired ambient temperature. WarmlyYours thermostats will do the work for you by energizing the floor for longer cycles.

The TempZone™ twin conductor cable present in our TempZone™ products is comprised of a double-insulated, coaxial heating cable. The total thickness of the system can be between ⅛” and 5/32” thick and will not noticeably affect the height of your installed flooring.

Yes, if the flooring manufacturer recommends this installation method. In most cases, the heating element will still need to be embedded in self-leveling cement before the flooring is installed.

There are heating systems designed for floating floors, such as our Environ system. However, the flooring must be rigid enough so it does not mold itself to the heating cables over time.

Check the flooring manufacturer's floor heating recommendations. In most cases, the heating system will need to be embedded beneath the flooring. Check for all "flatness" requirements for the flooring you choose. The flattest floors utilize self-leveling cement when installed correctly.

The TempZone™ Flex Rolls, Easy Mats and Shower Mats are designed to deliver 15 watts per square foot (maximum allowed by the National Electrical Code), with the heating element positioned 3” apart on a serpentine loop attached to a fiber mesh. The TempZone™ Cable yields between 8-12 watts per square foot, variable, based on the cable spacing. TempZone™ Custom Mats are made to order, so the spacing of the heating element throughout the mat varies according to each specific design. The TempZone™ Custom Mats can yield from 12 to 15 watts per square foot.

Test the TempZone floor heating cable using a digital ohm meter as shown here.

The amount of amperage draw depends upon how large the area is that you are heating. For coverage of areas less than 30 square feet, a 120V TempZone system will draw less than 4 amps. If you have a larger area over 240 square feet of heated space, then you will need a larger breaker plus additional controls. No matter what the size of the area you choose to heat, we recommend a dedicated circuit for your electric radiant floor heating system.

Single Conductor vs. Twin Conductor Identification

• A single conductor floor heating system is a loop of one core wire, it starts at the thermostat and ends at the thermostat - this is the original method of manufacturing heating cable. Most single conductor floor heating systems have the same color cold lead wire connected to both load terminals/pigtails of the thermostat. Some early single conductor floor heating systems were produced with a white and a yellow cold lead wire.
• A twin conductor floor heating system terminates two core wires at the end, both wires start at the thermostat - this is the current method of manufacturing heating cable. Most twin conductor floor heating systems will have two different colored cold lead wires, and one of these is black. The other wire in a WarmlyYours floor heating system is either yellow (120V system) or red (240V system).  A few early Environ systems had two black cold lead wires.

Note:

- Not all heating cables are wired directly to the thermostat. It may have been necessary during installation to terminate the heating cable in a junction box, and then run a separate (contractor-supplied) wire from the junction box to the thermostat.

- WarmlyYours single conductor cold leads were produced with a 13‘ length at the start of the loop, and a 26‘ length at the end.  The 120V floor heating systems had a yellow and a white label attached to the cold leads, and the 240V floor heating systems had a red and a white label attached. 

- If you have a single conductor floor heating system and notice that one cold lead is thicker or feels hotter than the other, please contact technical support at +1 (800) 875-5285 

It cannot be shortened, and all TempZone™ heating cable must be used at appropriate spacing.

Spacing is 3“ wire to wire.  Spacing when the wire installed in Prodeso installation membrane is 3.75“

A variance of +/- 15% is acceptable.

Temperature affects core resistance - lower temperatures decrease resistance and higher temperatures increase resistance. Another consideration is the test equipment, sometimes switching test units, adjusting the calibration, or allowing for the verified differential may be necessary.

Resistance greater than this value may result in overheating or even total failure of the floor heating system. This may be caused by a crimping or other damage to the wire.

Resistance below this value may result in no heating or cold spots in the floor. This may be caused by exposure to moisture or other conductive material that penetrates the core insulation.

Yes, we recommend using the Tempzone system encased in ⅜“-½“ of self-leveling cement followed by LVT.

Pricing for TempZone Cable heating product typically starts at $6 per sq. ft. ($7 CAD) when installed with Fixing Strips and $9 per sq. ft. ($11 CAD) when installed with our Prodeso Cable Installation Membrane. 

The wire spacing in the Prodeso Cable Installation Membrane is 3.75“, or every 3rd peg.

The ground wire in the floor mat must be connected directly to the ground wire of the supply or to the house ground wire.

Both are 15 feet long.

For systems below 12 Amps, a 15 Amp, Non-GFI breaker is fine. For systems 12 to 16 Amps, a 20 Amp, non-GFI breaker is needed. Breaker sizes are noted on the installation plan that ships with many orders.

Test the product using a digital ohm meter as shown here.

And here is a video showing how to do the test.

The shower and bench heating systems are offered in 120 voltage.

The cold lead is 22‘ long and the sensor(included with the thermostat) wire length is 15‘.

A digital meter with a 0-200 Ohms scale ( Ω ) to measure the heating wire's resistance, and a 20K scale to measure the sensor's resistance.

For Tempzone it is 51 BTU’s per square foot per hour and for Environ, it is 41. Take the wattage of the product (shown on the product’s label) and multiply that by 3.41. That is the BTU value for that product.

Test the single conductor heating cable using a digital ohm meter as shown here.

Spot heating is a method of floor heating where you only install heating elements under the most highly used portions of a floor (for example: the area in front of a vanity in a bathroom or in front of the stove in a kitchen). Spot heating allows you to enjoy all of the comfort of full coverage floor heating but for only a fraction of the material and operational costs.

Yes, the areas without heating elements installed directly under them will be largely the same temperature as they would be if there was no heating system at all. So you'll want to keep that in mind when you're looking to use spot heating in your floor heating project. You can always choose to have multiple TempZone Easy Mats incorporated into your project to created several heated "spots".

Simply set your floor heating thermostat to a comfortable temperature to maintain a nice warm floor. Your room will feel warmer and, typically, your furnace will cycle less often.

Yes, we offer several options to help make your floor heating system water resistant or waterproof. Our TempZone product line is designed for wet areas - making it completely safe for rooms that will have water on the floor at times or may experience leaks or flooding. We also offer waterproofing bands for our TempZone Cable + Prodeso Uncoupling Membrane system. Allowing you to waterproof all seams and the perimeters of the wall - guaranteeing that your floor heating system stays safe and prevents water from leaking to areas below.

Having floor heating installed and set to a higher temperature during particularly cold days will help to maintain a comfortable temperature level by providing supplemental heat.