Heated floors are becoming one of the top must-have features in modern homes — both in new home construction and in retrofits.
With a growing range of designs to choose from, homeowners are discovering what people around the world have known for thousands of years — radiant floor heating is clean, quiet and comfortable.
The Romans channeled hot air under the floors of their villas, and the Koreans channeled hot flue gases under their floors. You have all seen radiators in older homes. Radiant heat went out of style with the advent of the forced air furnace, but it has lately made a comeback.
Radiant energy transfer is caused by a warm surface giving up its heat to a cooler surface. Radiant heat can be distributed from wall or ceiling panels, baseboard units or through flooring, but the flooring option is most popular.
Because warm air rises naturally, heated floor systems are more efficient than conventional forced air systems. More importantly, heated floors are a practical luxury. All types of homeowners value the draft-free, cozier ambience of a home with radiant floors.
Whether you just want to take the chill off a bathroom floor or warm every room from the kitchen to the garage, there are floor-heating solutions customized for every location and lifestyle. Costs and labor to install radiant floor heating run from moderate to extravagant, depending upon your needs. As products have evolved, homeowners now have more competitively priced options to choose from.
Most floor heating systems transfer heat through water tubing (hydronics) or through electric cables (electricity).
The most common type of radiant heating is hydronic. This system uses a boiler to heat a fluid (often water), which travels through a series of pipes and transfers heat into a space. Some of the early floor pipes were made of copper or steel tubing, but they were vulnerable to corrosion and leaking. The material of choice today is PEX (cross-linked polyethylene), which is more reliable and flexible, and therefore easier to install.
Another form of radiant flooring uses electricity. Electric cables embedded in thin mats are used instead of pipes to conduct heat through or under flooring material.
This system can be installed adding only about 1?8 inch to the floor height, which makes it useful in some remodeling situations.
Electric systems also have a faster response time than hydronic systems and are easier and less expensive to install. However, an electric mat is most often used in a limited area to enhance comfort rather than provide primary heating.
What if you want radiant floors but don’t want to tear out your existing floor? There are options.
You can install an under-floor radiant system. The radiant material goes under the existing floor between the floor joists. The under-floor radiant heating system is most commonly used with a hydronic system. Keep in mind if you are dealing with your existing floor, you have to conduct enough heat to transfer completely through the existing floor and the subfloor so the heat can then radiate out into the room.
With an under-floor system, the water in the system must be heated to a higher temperature than an in-floor system.
There are several advantages to radiant heating. It is the most comfortable form of heat because it heats objects rather than air, providing a steady, even heat. Unlike forced air, floors, rather than ceilings, are the warmest parts of the room — because “hot air” rises but “heat” can go any direction. Because it warms your body instead of the air, people generally feel comfortable at a lower temperature, which means you can set the thermostat lower and save money.
You can even boost the energy efficiency by coupling a radiant heat system with a geothermal heat pump or a solar heat collector.
A geothermal system uses the natural heat from the Earth to pre-heat the water used in a hydronic radiant floor system. A geothermal heat pump is only capable of heating the water to a maximum of 115-degrees, so it works best when paired with radiant slab or an over-floor radiant system. Under-floor radiant does not work with geothermal.
Solar heat collectors can be used with two types of radiant floor heating systems: radiant air floors and solar hydronic radiant floors. Both systems use the sun to heat the fluid (air or a liquid) in the collectors. The thermal mass of the floor (the fact that it is “solid” and “deep”) acts as both a storage battery and a heat sink to manage the temperature. Solar heat systems require a back-up heating system for the cloudy days. Depending on the size of the house, a conventional domestic water heater may be sufficient as a backup heater.
Whole-house radiant heating systems initially cost $14,000 or more. In contrast, a conventional heating system might cost $4,000 to $8,000 for the same size house. A simple electric mat installed under a new tile floor costs about $500 for the average bathroom. Costs obviously fluctuate depending on the size and type of system installed.
Overall, radiant heat is an attainable luxury. The practical advantages make it a viable option for any homeowner to consider, especially if you are planning a remodel that involves new hard surface flooring. While it is not going to replace convention heating methods due to the higher front-end cost, this ultra-comfortable approach is definitely making a comeback.
Architects Ann Robinson and Annie V. Schwemmer are the founders of Renovation Design Group, www.renovationdesigngroup.com, a local design firm specializing in home remodels.
