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.
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
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.
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.
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.
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.
Yes. Unlike the heating cable for electric floor heating, the cold lead wires can be trimmed.
To prevent any overheating, we recommend that you do not install any electric radiant floor heating elements closer than 4" from the wax ring.
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.
When installing electric floor heating over a concrete slab, an insulating underlayment like CeraZorb is highly recommended to ensure efficient operation, faster heating times and warmer floor temperatures.
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).
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.
Yes, the drying effects of electric radiant floor heating will reduce the humidity coming from the slab, which is the largest source of moisture.
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.
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.
The answer to this question will depend on a whole host of variables related to electric floor heating, including, but not limited to, the run time (for supplemental heating, we usually recommend between 4-8 hours per day), the electric radiant floor heating system you're using, the total square footage, and your local electrical cost. Typically, the cost is just a few cents a day.
To figure out how much electric floor heating might cost to run for you, make sure to use our interactive Operating Cost Calculator.
Yes, our TempZone Heating Products can be used for heating luxury vinyl tile or luxury vinyl planks in any indoor application.
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.
Electric-resistance heating cables and systems have no polarity. This includes all current WarmlyYours heating elements.
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!
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.
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.
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.
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.
A floor heating system can work as a supplemental heating source and make the basement warmer. If more heat needs to be added to the room, you can experiment with setting the floor heating thermostat to higher temperatures.
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, the system will draw less than 3 or 4 amps. If you have a larger area over 120 square feet of heated space, then you may 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.
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 Radiant Panels, which are wall-mounted and use infrared technology to provide supplemental heating.
The temperature of your floor can range anywhere between 75°F to 95°F. The floor's actual temperature will depend on a number of factors including the amount of heat loss that the room experiences as well as the room’s configuration. For instance, the warmth contained in a two story entry way would likely be less than that of a smaller, more enclosed area such as a bathroom. In a bathroom that is located on the second floor of your home or over another floor in your home that is typically heated, the temperature of your heated floor should easily reach a comfortable temperature of 85 degrees Fahrenheit, if the electric floor heating system is installed correctly. For the heat loss calculation for your specific room, 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.
While both hydronic (heated water) and electric floor heating systems perform a similar function by providing radiant heat from beneath your floor, they do differ in some pretty crucial ways. Typically, using hot water instead of electricity will result in lower operational costs but significantly higher investment and maintenance costs. This usually means that hydronic heating systems are reserved for new construction projects (where it is easier to incorporate the boilers and pumps needed to operate the system) and electric floor heating is often used for remodeling projects in bathrooms, kitchens, etc. To learn more about the differences between these systems, check out this post.
Typically, electric floor heating is used as a supplemental heat source but in some cases, it can be used as a primary heat source. Electric floor heating is more energy efficient, less prone to spreading dust and allergens, and easier to control from room to room. Air-based heating systems can be used for both heating and cooling and can be a good way to control air quality in the home with regular maintenance.
For a more in-depth answer to this question, check out Your ‘Cheat Sheet’ for Radiant Heat vs. Forced Air.
Electric floor heating works by having an electric heating cable installed underneath the flooring (embedded or floating, depending on the system and floor type), which is then wired to a special thermostat (either one specifically designed for electric radiant floor heating, like a WarmlyYours’ nSpiration Series control, or a third-party thermostat). When turned on, the heating cable emits heat upward through the flooring which is then radiated throughout the room, heating all solid surfaces.
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.
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 CeraZorb synthetic cork.
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, 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.
Breaker and wire sizes are selected based on the total amperage of the heating system connected to a single thermostat. This information is on the heating product'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.
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.
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.
A typical bathroom floor can be heated for about a quarter a day with electric radiant floor heating.
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.
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 product that you're 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.
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.
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.
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.
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.
Yes, we have TempZone Shower and Bench mats with sizes designed specifically for shower installation and they are wet location listed for for installing electric radiant floor heating to a shower.
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.
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, 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.
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.
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.
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.
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.
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.
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?
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 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.
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.
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.
Our TempZone electric floor heating products are waterproof and wet location listed.
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.
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.
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.
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.
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:
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.
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.
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.
Waterproofing for the room is in the layer above the floor heating system. The layers for waterproofing this type of floor are:
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.
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.
There is a way to install floor heating that makes it suitable for any type of floor. By embedding our TempZone systems in self-leveling cement (SLC), you have created a heated subfloor. Almost any low r-value flooring can be installed directly over this for heated floors.
A Warmly Yours indoor floor heating system should not be installed with a GFCI breaker because GFCI protection is built into the thermostat and power module. And while it's not always required, we strongly recommend a dedicated circuit for each thermostat and power module to limit the occurrence of ground fault nuisance tripping caused by multiple GFCI devices on a circuit. The amperage of a breaker would depend on the amp draw of the heating system. For example, a TempZone Flex Roll (which provides approximately 15 watts of energy output per square foot) that is providing 15 square feet of heating coverage will draw only 225 watts ( 1.9 Amps), so a 15 Amp circuit would suffice. Always size breakers according to your local Electrical Code requirements.
Do not wear spiked shoes when installing SLC. When installing, you can walk on the wires, but not the factory splices. Minimize traffic on exposed wires and wear soft-soled shoes when working over the wire.
In some cases it is possible to install embedded electric floor heating over existing tile floor. You will need to check with your flooring manufacturer to see what requirements they have for the subfloor. Once you have that information, we can make a recommendation on whether floor heating will work for your project. A specific type of thinset may be needed for this application. In most cases you will need to repair or replace damaged existing tiles. They should then be scuffed or sanded, and then cleaned. After these steps have been completed, the new tile could be installed using the appropriate thinset.
An area where large furniture will cover the floor should have enough clearance underneath to allow air to circulate. Any areas where floor heat may be trapped (rugs, box bottom furniture), let your sales rep know so we can design an installation plan around these areas.
Yes, you can install multiple sensors while installing the floor heating system. Only one of these sensors should be connected to the floor heating thermostat. Any secondary sensors can be run through conduit up to the thermostat area to be connected in the future should anything happen to the original sensor. The sensor is low voltage and may not need conduit. If conduit is required, it will need to be separate from the return power leads.
Hydronic systems operate by using heated water pumped through tubing beneath the floor. Electric underfloor heating works with heated cables beneath the floor. Typically, hydronic systems are a good choice for new construction projects and electric systems are better for remodels or single rooms. This is because the high installation costs of hydronic systems (boilers, pumps, etc.) makes them cost-prohibitive for projects like a bathroom or kitchen. Electric radiant heating systems are also easier to repair than hydronic systems if they're damaged.
For a more complete answer to this question, check out this blogpost.
Cork flooring can be used with floor heating if the r-value is under 1. You will need to find the r-value of the flooring you choose and let your account manager know during the design stage. Cork flooring should have a low r-value to minimize trapped heat.
For best results, we recommend a 1”- 1.5” maximum distance between the heating cable and the top of the floor. Depending on your thinset or self-leveling cement thickness, this will leave roughly an inch or less for maximum tile thickness.
When WarmlyYours 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 systems provide 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 floor warming system.
When installed on top of a concrete slab without insulation, it is generally accepted that a radiant floor heating system 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 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 CeraZorb synthetic cork.
One thermostat can control multiple heating mats/cables as long as all the elements are using less than 15 amps. For TempZone™ Flex Roll systems for example that would be maximum of 120 sq.ft. for 120V systems and 240 sq.ft. for 240V.