As autumn rolls around and the temperature starts to drop, consumers inevitably start thinking about their heating costs. One way for them to potentially save on their gas or oil bill is to install energy-efficient underfloor radiant heating systems to keep surfaces warm and comfortable without resorting to cranking the furnace. FCI spoke with manufacturers of electric underfloor radiant heating systems to find out more about their latest products, proper installation techniques and how to calculate the amount of material needed to complete the job.

Proper installation techniques

Before installation can begin, Isabelle Marcil, communications coordinator, FlexTherm, cautioned to always check the subfloor to make sure the surface is clean, flat, smooth and free of protruding nail or screw heads that could damage the cable. “Installers should always consider the starting point and map out the cable layout before actually installing the product. An installation plan can help foresee direction changes, obstacle skirting, etc.”

Marcil also advised taking into consideration fixed elements such as kitchen islands, where heating cable cannot be installed, and buffer zones (such as behind a door or next to the toilet) that can accommodate any excess cable, as needed.

“Also, plan where you will install the thermostat’s floor sensor,” she added. “It should be placed between two cable runs in a spot that will not be covered by a carpet or rug, nor will find itself directly in a sunbeam coming through a window, as this increased temperature will lead to a false temperature reading in the room.”

Peter Leal, EasyHeat product marketing manager, Emerson Industrial Automation, describes a quick 4-step process. “For EasyHeat’s WTE mat systems: 1) Apply a thin layer of mortar to the floor; 2) Lay down a mat system; 3) Apply thin set; and 4) Lay down and install the floor tile or laminate surface.”

Julia Billen, owner and president, WarmlyYours, offered a couple of other helpful tips, such as testing the electric floor heating system with an ohmmeter at every major stage of installation and then recording the readings, which helps ensure the product is functioning properly. She also mentioned the significance of anchoring the heating element to the subfloor with tape or hot glue.

“Most floor heating systems will be covered with self-leveling cement to ensure a flat surface for installing the floor covering. By anchoring your heating element to the subfloor, you’ll prevent it from floating in the self-leveling cement. If you use hot-glue, spreading it out will help decrease drying times.”

Russ Dunn, vice president of marketing, ThermoSoft, mentioned that installation subtleties will vary based on the subfloor, floor heating system, finished floor covering, climate and the preferences of both the end user and the installer.

“Some of these installation subtleties include whether or not to install a thermal break, an uncoupling membrane, a vapor barrier, a skim coat of thin-set, a layer of self-leveling cement, a waterproofing membrane and when to use modified versus unmodified thin set.”

The Tec In-Floor Heat Panel System is designed to save installers steps and time, claimed Dan Tambellini, spokesman for H.B. Fuller/Tec, and the system can be customized and configured on a job site. The heat panel mat is available from a distributor in a 550 sq. ft. roll that a contractor can cut to length and/or width to fit the room layout needed, and it can be wired for either 120V or 240V AC power.

“Electrical current-conducting copper bus bars run down the length of the heat mat. Under no circumstances should the active areas of the heat mat be allowed to overlap itself or onto adjacent pieces of the heat mat,” he cautioned. “The heat mat can be installed with either side of the mat facing up or down, but the mats should be at least 6” from the wall. Edge sealing tape should be used to seal any cut ends of the mat.”

Tambellini stressed that a licensed electrician must hook up and connect the thermostat to the in-floor heating system. In fact, Tec recommends consulting an electrician to determine where the electrical supply needs to be, and where to place the thermostat. In addition, an electrician should test the electrical supply connection to the heat mat and sensor.

Each product line from WarmlyYours has its own best practice for installation “but one great feature all of our electric floor heating systems share is how easy it is to test your product throughout the installation process,” stated Billen. “Our Circuit Check product monitors the electric floor heating system throughout the installation for both continuity and potential shorts, audibly alerting the installer if any issues occur. This keeps any issues from going unnoticed before the floor covering is installed and repairs become costlier or more difficult to perform.”

Calculating the amount of material needed

“We have four sizes available (1.5x5, 1.5x10, 3x5 and 3x10) and there are two ways to configure a room,” stated Jack Boesch, director of marketing, MP Global Products. “First, you can install wall-to-wall coverage for the maximum amount of warmth addition to the room, [and accounting for fixed objects] you’ll only need about 80% of the room’s total dimensions. Or you can spot heat, meaning you can place the mats where you’ll want the most foot comfort.”

Monica Irgens, president, STEP Warmfloor/Electro Plastics, said customers will send in their project information indicating the area(s) they want to heat and STEP Warmfloor makes, if applicable, a heat loss calculation to know the heating requirements. “STEP Warmfloor calculates and makes the design, including CAD drawings, element layout, work sheets and energy consumption to satisfy the consumer, the flooring installer and the electrician.”

Wally Lo, product manager, Pentair echoed these sentiments. “All you need to do is draw a rough sketch of the room with the dimensions and our design team will calculate the square footage for you and provide an AutoCAD drawing outlining the shape of your mat along with the amperage. Your Nuheat Mat will arrive in a box that is ready to be rolled out—no calculations or on-site modifications are required.”

Dunn added some helpful elements when factoring in the amount of material needed for a job. “To order the proper amount of radiant floor heating materials, first determine the heated area square footage. The heated area excludes heating under cabinets, fixtures such as tubs and toilets, appliances such as refrigerators, ovens and dishwashers and a minimum 3” space from the walls.

“The square footage can be determined by dividing the heated area into rectangular areas where the length and width can be easily calculated. Knowledge of basic geometry is helpful—for example, to calculate the square footage of a triangular area, multiply the base and height of the triangle and divide by two.”

Accurate measurements really are the key to a successful installation, noted Marcil. “Double-check all measurements to make sure you select the right product and have enough cable to cover the entire surface. Keep in mind that extra cable cannot be cut nor installed inside walls and that the spacing between cable runs must remain the same throughout the entire installation.”

Being able to quickly and accurately calculate the material needed to complete a job has always been an issue for professionals, especially when it comes to floor heating, expressed Billen. This is why WarmlyYours developed two different avenues for getting that information to busy installers as quickly as possible.

“The first and most expedient option is our online Instant Quote Tool. By simply entering project details like the projected floor covering, room type and dimensions, you receive an instant side-by-side comparison of the different floor heating products that would work for your project. This comparison also includes the pricing and information about the installation process for each system.

“The second option is the WarmlyYours SmartPlan. By supplying us with some information and a simple floor plan drawing of the project, you’ll receive an itemized product quote, an electrical plan and an installation plan for free and within one to two business days.”

The latest products

“We really have three radiant heat products, but the two carbon ink film versions are relatively new for us,” Boesch noted. “Both are gentle radiant heat films designed specifically for under floating engineered wood and laminate floors and the other film is embedded into an anti-fracture membrane that prohibits any cracking in the tiles and easily allows thin set to adhere to it in the tile installation. QuietWarmth Radiant Heat systems are a value-adding install that many homeowners and builders are looking for.”

Leal stated, “Our WTE (Warm Tiles Elite) mats system feature an ultra-thin 1/8” (0.125”) high heating cable system that conducts heat to the floor surface in the most efficient way. Their pre-manufactured design allows for quick installation, permitting jobs to be completed in one session. Mats consist of heating cables interwoven into slim, durable fabric and come in standard square and rectangular sizes, or can be made in custom sizes to accommodate angled and irregularly shaped rooms.”

Irgens described the energy-efficient STEP Warmfloor heating system. “The heating elements are very versatile and can be used for whole-house heating, complementary heating and floor warming in residential, commercial and industrial applications. Other applications include snowmelt and roof deicing, as well as heating RVs, ships and electronics.”

Thermosoft works hard to be a one-stop shop of electric radiant floor heating systems and supplies for installers of all flooring types, expressed Dunn. “Our flagship product, ThermoTile, is an easy-to-install cable-on-mesh system designed for tile, stone and most any other floor covering once it’s embedded in thin set mortar. We were the first to introduce a product, ThermoFloor, for installation directly under floating laminate and wood floors that includes an integrated thermal break and does not require cement for installation.

“Our latest product additions include ThermoSlab for new construction installation in the slab and specialty heating systems for the bath including ThermoTub bathtub heaters, ThermoShower pre-fitted shower floor heating mats and ThermoClear mirror heaters.”

According to Judi D’Amico, Watts Water Technologies direct marketing manager, “Two of our hottest products are the WarmWire heating cables that go into an underfloor heating system, and the snowmelt systems. The snowmelt seems to be getting a little more attention these days.”

The FLEXSnap+ system represents the second generation of Flextherm’s radiant floor heating installation system. “FLEXSnap+ makes it possible to install a floor heating system and floor covering in a single day,” said Marcil. “It is the only system of its kind; not only does it replace the second subfloor but it is compatible with all cement-based self-levelers. The system can also be installed with mortars and can be secured to a plywood, OSB or concrete subfloor and can be covered by any type of floor coverings (except for cork and natural hardwood, which are not recommended over a heated floor).”

Billen described one of her company’s newest products—the Prodeso Cable Installation Membrane for use with electric floor heating cable. “Historically, one of the primary reservations installers had about installing underfloor heating was that it could extend installation times. Installers had to wait for the self-leveling cement the heating element is embedded in to cure before they could install the floor covering.”

She noted that the Prodeso Membrane allows installers to begin working immediately. After adhering the membrane to the subfloor, installers can run TempZone heating cable through the channels in the membrane, which are already properly spaced. Then they can begin work immediately on installing the floor covering.

“Our Nuheat Signature was the first WiFi-enabled floor heating thermostat, and now is the first ever to work with Nest and Control4,” noted Lo. “With this added integration, your floor heating can now adjust automatically based on home occupancy for energy efficiency and home comfort. We have also continued to perfect our Nuheat Mats, which are the only pre-built custom solution on the market. With our educated sales force, design team and technical support we provide on-site measures or over the phone to make it even easier for the customer.”

Tambellini said Tec In-Floor Heat “provides uniform warmth throughout the floor. The Tec In-Floor Heat Panel System is customizable on-site to fit any space, and does away with embedded heating wires that need to be patterned.”