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Radiant Floors

Combine heating and flooring for efficient warmth underfoot

You've probably heard about it. If you've checked out any new or remodeled homes in more upscale neighborhoods, you may have felt it as you viewed the house wearing the little blue fiber booties encouraged by sales agents. It's one of those home improvements that seem expensive, but can return significant value on your investment over time.

Radiant floor heat isn't new. It's was used in homes at least two thousand years ago by the Romans, who used below floor ducts with heated water to warm their villas. During the 1940s and 50s, architects revisited the past and specified radiant systems using copper and iron pipes embedded in concrete slabs...even in tract homes. The systems worked like a dream...until corrosion and breakage damaged the metal pipes. Radiant floor heating systems fell out of favor as homeowners paid plenty to replace them with more conventional systems.

Electric or Hydronic?

Radiant heat is now available in two flavors: hydronic and electrical.

The hydronic systems use warm water that is circulated through a tubing system installed within or just above the subfloor. Innovations in plumbing technology have resulted in a new tubing material called PEX (cross-linked Polyethylene). The resulting material works well in temperature extremes, from below freezing to hot water applications of up to 200 degrees. That makes it ideal for radiant heating systems. It is being used now in many plumbing applications because of its durability, resistance to chemical agents, and flexibility as well as being easily installed and repaired. Hydronic radiant systems are now widely used in Europe and are finally beginning to regain favor in the US.

The electric method is similar to a heating pad or electric blanket, and is also installed just above the subfloor. This system uses low-voltage insulated cables (8–15 watts) that can be embedded in an underlayment or mats with the cable embedded.

Both systems are compared in the following table:

  Hydronic Radiant Heat Electric Radiant Heat
Cost
  • Relatively expensive to install; requires a boiler of some type to heat the water.
  • Less expensive than hydronic to install.
  • Cost can be figured per square foot.
Thermal mass
  • Heats slowly, retains heat longer.
  • Fewer fluctuations in temperature, results in fewer stresses on flooring materials such as wood.
  • Heats more quickly, but loses heat faster, too.
Fuel
  • Flexible in choice of fuel source for boiler. Can take advantage of gas, oil, electricity, solar, or geothermal.
  • Limited to electricity; cost may increase over time. Use of off-peak electricity can reduce cost.
Best for...
  • New construction, expecially when designed as an integral part of the heating system.
  • Retrofit or limited installation such as just bathrooms.
  • Short-duration, limited use such as early morning for showers or evening bath time with the kids.
  • Well insulated homes using passive solar with relatively low heating loads.
Advantages
  • Environmentally friendly.
  • Quiet.
  • Low maintenance.
  • Lowers heating costs by as much as 30%.
  • Clean.
  • Right application can be more cost effective than hydronic.
  • Quiet
  • Clean
How does it work?
  • Using a continuous loop of PEX which is embedded in a poured concrete floor or secured to other subflooring, warm water continuously runs through the tubing and is transferred to the flooring above.
  • Similar to the hydronic system, but uses either cables or a mat with cables woven in instead.
  • Cable is less expensive than mats, however, mats are faster and easier to install. Mats also have the advantage of adding less height to the floor with less resulting need for altering doors or window heights.
  • Some systems can be installed beneath a carpet and pad for a minimal installation.

Resources

Do you need a qualified professional to evaluate your home for a radiant flooring system? Find one now at ContractorNexus .

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