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Figure 3 – (left) An example of a floor heating “roll” that is modified to fit a countertop. The large gap between elements, along with the difficulty of applying them close to the edge, introduces uneven heating on the top surface and cold edges. (right) This FeelsWarm heating element, specifically designed for countertops, has patterns with spaces of under ¼ in. to avoid uneven heating problems. Figure 2 – The combination of higher voltage and temperature sensing systems common in floor heating systems creates heat pulsing with a fast heat rise followed by a delayed power-off stage that repeats continually. Unfortunately, when used for countertop applications, this can lead to cracking. by high voltages (household power of 120 or

240 volts) in order to get the needed wattage

output. Floor heating is controlled using a closed loop control scheme where a sensor provides feedback to the electronic control device

on what the temperature of the floor is. The

combination of higher voltage and a temperature sensing system creates pulsing of the heating

element that institutes a fast heat rise followed by a delayed power off stage. This repeats continually to arrive at an average surface

temperature. Unfortunately, this can lead to

cracking (see Figure 2). In this example, Derek Dykstra, a custom home builder in California, used a floor heating system as a countertop

heater. Within 24 hours of activating the heater, the stone cracked on the surface. Per Derek Dykstra, “The countertop would lie perfectly

flat while cold, but once the heat was applied,

the countertop would heave at its seam,” said

Dykstra. “Eventually, the crack grew across the width of the slab.”

However, after repeating the identical job using a heating system specifically developed for

countertop applications, there were no further

problems and Dykstra now has a happy customer.

But, that can be a pretty expensive lesson to learn. Risk-free Solution Within the past year, a technical advancement of electric radiant heaters has occurred that

specifically addresses the obstacles with heating countertops. Electric heating mats utilizing

ultra-thin elements have become available in

large-format custom shapes and sizes. Ultra-

thin flexible heaters operate on low voltage and

utilize flat foil as the resistive conductor instead of


Figure 4 – FeelsWarm heaters eliminate thermal stress and resulting potential to crack, and come in two formats: (left) custom configurations, and (right) “peel and stick” formats for quick application or pre-existing countertops. FeelsWarm heaters are for quick application. thick round wire (see Figure 3). These “etchedfoil” based heaters are laminated between thin high-performance plastic films constructed of Polyimide or PET (Polyethylene Terephthalate) polymer materials to create a very rugged and dependable heating mat. The resulting heater can be as thin as 0.010 in. thick. Etched-foil heaters are also patterned so that the conductive heating element will match the shape and size of the countertop, will come close to the edge, and will have narrow spacing between elements—around 0.25-in. gaps (see Figure 4). These heaters can be adhered to the underside of stone countertops using pressure sensitive tape for quick installation. The flatness permits the heater to be sandwiched between the stone and the cabinet without introducing a reliability risk or without having to mill out areas to compensate for thickness. These heating pads are designed to provide very gradual heat rise by operating under low voltage (12 to 24 volts), and each heater is supplied with its own transformer. They are available in both custom configurations and standard sizes and shapes. Each “plug and play” heater/transformer plugs directly into a standard 120-volt household outlet without the need for custom wiring or an electrical contractor. The typical installation utilizes an outlet that exists inside the cabinet or

under a desk. Current draw on the outlet is 0.6 to 2 amps, depending upon the square footage of the heater.

Looking Forward Given their elegant appearance and regal feel,

few doubt that stone countertops will remain as a mainstay in luxury homes and businesses for decades to come. Addressing the cold feel of

these countertops is just another way to expand upon their luxury. Fabricators and contractors

who haven’t been introduced to this application may very well be as homes get more and more sophisticated. However, to avoid sub-par

quality in feel and performance, as well as

eliminate the added risk of cracking a premiere and expensive countertop surface, it is wise to

look for a product specifically designed for this use when undertaking a project of this nature.

Ultimately it will lead to a happier customer and a more profitable outcome.

About the Author Jahn Stopperan is a senior product development engineer and business manager in low voltage electronic assemblies and devices. He has more than 25 years of experience in technology/product development and management at a variety of companies. He holds more than 12 patents, and is a speaker and author. For more information visit or contact Stopperan at (952) 898-9505, ext. 3 or jstopperan@ International Surface Fabricators Association • Vol. 7 / Issue 3 • 25

ISFA's Countertops & Architectural Surfaces Vol. 7, Issue 3 - Q3 2014  

Countertops & Architectural Surfaces is the official publication of the International Surface Fabricators Association (ISFA). It contains th...

ISFA's Countertops & Architectural Surfaces Vol. 7, Issue 3 - Q3 2014  

Countertops & Architectural Surfaces is the official publication of the International Surface Fabricators Association (ISFA). It contains th...