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TempZone™ Floor Heating Ruler Cable Frequently Asked Questions

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Frequently Asked Questions

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

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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.

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

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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.

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No. TempZone™ Ruler Cable should not be installed under nailed flooring types. If your project requires a nailed floor covering, use standard TempZone™ Cable instead, which is suited for that application. 


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As you install, compare the footage markings printed on the heating cable to the reference footages on your custom SmartPlan™. If they match at each reference point, you’re on track. If the cable reading is higher, too much cable was used in the previous section; if it’s lower, you used less cable than designed.

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An uncoupling membrane like Prodeso provides a flexible layer between your subfloor and tile, preventing cracks caused by natural floor movement. It also offers waterproofing and vapor management, making it ideal for bathrooms. Plus, the membrane’s studs make cable installation fast and consistent without the need for staples or glue.

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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.

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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

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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.

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WarmlyYours’ TempZone™ product is most commonly installed under tile, stone, and marble flooring, but can also be installed under many other popular floor covering options such as hardwood, vinyl and linoleum. We also have our Environ system, which is an electric floor heating product as well and is specially designed for installation under carpet (in the U.S. only), laminate and floating wood. WarmlyYours can accommodate any flooring type with either of the electric radiant floor heating products that we offer. If your flooring type isn't listed here, just give us a call at (800) 875-5285 and we will be happy to discuss it with you.

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

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Electric radiant floor heating should not be installed under permanent fixtures that may trap heat. However, if the vanity or cabinets are "floating" or are on legs, then a floor heating system may be installed under it.

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Please keep in mind that you must check your electric floor heating system with a digital ohmmeter in conjunction with a Circuit Check™. Take an initial reading as soon as you take the product out of the box to verify that it is within -5% / +10% of the values stated on the product’s label. This will give you a basis of comparison for future readings. Take a second reading once you have positioned the system to match your custom installation plan. It is also advisable to take an additional reading in the middle of the tile installation, just to make sure that the Circuit Check™ is doing its job. Then, take a final reading when you are finished with the floor installation and are ready to hook up the thermostat.

The Circuit Check™ is a tool developed by WarmlyYours to give you peace of mind and ensure trouble-free installations. Simply hook up the cold leads to the tool while you position the system to match your custom installation plan.

The Circuit Check™ will continuously monitor the continuity of the circuit during the installation of your system and during the installation of your flooring. The Circuit Check™ beeps immediately when a short in the system is detected, alerting you to a potentially damaged cable in the area you are working, before you lay the tile over the electric floor heating system.
 The WarmlyYours technical support team is available 24/7 to provide assistance if the alarm sounds, or if you would have any questions during your installation.

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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.

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

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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.

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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.

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Yes. While there are some floor heating systems that can be installed beneath floor joists, most electric radiant floor heating systems will need to be installed beneath the floor itself. This is why the best time to install electric floor heating is during a remodel or as a part of a new construction, when a floor is being installed anyways. 

If you’re interested in alternative radiant heating methods, check out our Infrared Heating Panels, which are wall-mounted and use infrared technology to provide supplemental heating. 

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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.

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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.

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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

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One thermostat can control multiple heating mats/cables as long as all the heating elements are using less than 15 amps:

TempZone™ will cover aprx. 120 sq. ft. for 120V systems and 240 sq. ft. for 240V systems on one thermostat.

Environ™ will cover aprx. 150 sq. ft. for 120V systems and 300 sq. ft. for 240V systems on one thermostat.

Slab Heat will cover aprx. 90 sq. ft. for 120V systems and 180 sq. ft. for 240V systems on one thermostat.

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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.

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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.

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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.

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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.

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

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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.

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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.

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Yes, you can add radiant heating to an existing slab using "over-the-slab" systems like TempZone™ Flex Rolls or Easy Mats. These low-profile electric systems are installed on top of the existing concrete using thinset or self-leveling underlayment, allowing you to add warmth without tearing out the original floor.

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Never cut, shorten or splice the heating cable itself; cutting it damages the system. Only the non-heating cold lead can be shortened, as your product’s manual allows. Order the size your SmartPlan™ specifies, because unused cable can’t be cut off.

Some mats let you cut the mesh, never the cable, to turn or reposition them: TempZone™ and Environ™ Flex Rolls and Slab Heat mats. TempZone™ Easy Mats and Custom Mats are made to size and must not be shortened or cut. TempZone™ Cable has no mesh: lay all of it at the spacing on your SmartPlan™.

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Many homeowners choose to lay the heating mats or cables themselves as a DIY project while they are putting down new flooring. However, we always recommend that a licensed electrician perform the final hookup to the thermostat and power source to ensure everything is up to code.

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

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Yes. The finish layer needs to be 1/2" thick. This can be done if the brand of Self-Leveling Cement (SLC) is engineered to be a final flooring surface.  Most SLC products aren't designed to be the finish surface.

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It depends on the floor. Tile and other bonded floors shouldn’t go over a loose plastic sheet: bond ThermalSheet to a cured, dry slab with modified thinset; a waterproof concrete sealer may be needed if slab moisture is above 10%. Under floating laminate or engineered wood, a plastic vapor barrier beneath the underlayment is fine. Fix any water seepage first.

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Yes. Without insulation, a concrete slab draws heat down from the floor heating, so the floor warms slowly and uses more energy. Over an existing slab, lay ThermalSheet, WarmlyYours’ insulating underlayment, under the heating system to send the heat up into the floor. ThermalSheet replaces CeraZorb, which is no longer sold.

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It depends on your flooring type and heating system. For electric radiant floor heating, underlayment is often beneficial but not always required.When underlayment is recommended:

When underlayment is not needed:

  • Tile and stone installations: Heating cables/mats are embedded directly in thinset or self-leveling compound—no underlayment required.
  • Glue-down LVP over concrete: System can be installed in self-leveling compound without additional underlayment.

Important note: WarmlyYours currently offers ThermalSheet as our recommended underlayment solution. While CeraZorb and cork underlayment were previously available and may still be found in older installations, ThermalSheet is now our preferred product for optimal performance and compatibility.Our free SmartPlan service includes underlayment recommendations tailored to your specific flooring and subfloor. With over 600,000 custom floor plans created, we ensure you get the right system configuration.

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One watt equals about 3.412 BTU per hour. TempZone™ Flex Rolls, Easy Mats and Shower Mats, and TempZone™ Cable at 3-inch spacing, deliver 15 watts per square foot: about 51 BTU per hour for every square foot of heated floor. Environ™ delivers 12 watts per square foot, about 41 BTU per hour. For any product, multiply the wattage on its label by 3.412.

Only heated floor counts, and heating can’t run under cabinets or fixtures: 100 square feet of 15-watt heating produces about 5,100 BTU per hour. Compare that with your room’s heat loss.

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TempZone™ Flex Rolls, Easy Mats and Shower Mats deliver 15 watts per square foot, and Custom Mats 12 to 15. TempZone™ Cable and Ruler Cable deliver 3.7 watts per linear foot, so their output depends on spacing: about 15 watts per square foot at 3 inches, 11 at 4 and 9 at 5. See TempZone Cable spacing and attachment.

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Operating costs for electric floor heating depend on the heated area, system wattage, your local electricity rate, and how long the system runs: (area × watts per sq. ft. ÷ 1,000) × electricity rate × hours energized.

For example, heating a 35 sq. ft. bathroom with a 15-watt-per-square-foot system draws 525 watts (35 × 15 ÷ 1,000 = 0.525 kW). Running the system for 8 hours a day costs approximately C$0.62/day (C$18.65/month).

You can calculate specific operating costs for your project using our

Operating Cost Calculator for Floor Heating

Estimate your daily and monthly energy costs based on room size and local rates.
sq. ft.
¢/kWh
Estimated Cost
C$0.04
per hour
C$0.15
per day
C$4.50
per month
Rae Radiant

"Most homeowners are surprised how affordable radiant floor heating is to operate—often just pennies a day for a bathroom. It's the kind of everyday luxury that pays for itself in comfort!"

— Rae Radiant
.

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For the same wattage and operating time, 120V and 240V electric floor heating use the same amount of energy and produce the same heat. A 240V system draws less current for the same wattage, which can accommodate a larger heated area on a suitable circuit. Choose the heating product and control voltage to match the supply, and have an electrician verify circuit capacity, wiring, and applicable code.

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In TempZone™ Flex Rolls, Easy Mats and Shower Mats, the heating cable is fixed 3 inches apart. Custom Mats follow each design. TempZone™ Cable and Ruler Cable are spaced as you install them: 3, 4 or 5 inches on GripStrips™, or set by the membrane, and never closer than 3 inches. See TempZone Cable spacing and attachment.

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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.

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WarmlyYours floor heating systems are backed by our industry-leading warranties, among the longest in the radiant heating industry:

Product Warranties:

  • TempZone™ systems – 25-year product warranty on heating cables and mats
  • Environ™ systems – 25-year product warranty on heating cables and mats
  • Thermostats – 3-year manufacturer warranty on all models
  • Installation materials – Covered under respective product warranties

What's Covered:

  • Manufacturing defects in heating cables, mats, and components
  • Free replacement of defective products during warranty period
  • Technical support for troubleshooting and diagnostics
  • Installation guidance to prevent issues before they occur

Why Our Warranty Matters:

  • Proven reliability – Over 25 years of manufacturing experience
  • Rigorous testing – Every system tested before shipping
  • Quality materials – Premium components designed for decades of service
  • Installation support – 24/7 tech support during installation to prevent warranty issues
  • Peace of mind – Your investment is protected for decades

Warranty Registration:

Your SmartPlan™ includes warranty documentation and testing logs. We recommend:

  • Testing resistance before, during, and after installation
  • Documenting all resistance readings
  • Taking photos of your installation
  • Registering your system online after installation

Beyond the Warranty:

Even after your warranty period, our support team remains available to help with:

  • Troubleshooting and diagnostics
  • System expansions to additional rooms
  • Replacement thermostats and accessories
  • Technical guidance for any issues

Your SmartPlan™ ensures your system is properly designed and installed from day one, minimizing the chance of issues and maximizing the life of your investment.

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Keep the power lead factory splice and the cable end seal outside the shower area and at least 1 ft. away from shower openings or other spots normally exposed to water. The control must be located at least 4 ft. from shower openings, where it cannot be exposed to water or touched by someone in the shower.

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More output lets the floor make up more of a room’s heat loss. TempZone™ Flex Rolls, Easy Mats and Shower Mats, and TempZone™ Cable at 3-inch spacing, deliver 15 watts per square foot: up to 25% more heating power than the nearest competitor’s systems, and enough for primary or supplemental heat. Cable at 4-inch spacing, about 11 watts per square foot, is for supplemental heat only.

Whether floor heating can be a room’s only heat source depends on that room’s heat loss. An uninsulated concrete slab, for example, absorbs part of the heat, so insulating over it helps. WarmlyYours can calculate your room’s heat loss before you decide.

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A floor sensor measures floor temperature so a compatible thermostat can regulate comfort and enforce the flooring manufacturer’s temperature limit. Some thermostats, including nTrust 2.0, offer a regulator mode without a sensor, but that mode does not measure floor temperature. Use sensor-based temperature control whenever required by the flooring or heating-system instructions.

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