Pros and Cons of Radiant Floor Heating
Radiant floor heating turns your floor into a large-area radiator. The floor becomes a heated surface that directly warms the home. This floor can be “charged” during off-peak hours, when electricity is cheaper, and, if the thermal mass is large enough, it can keep a home comfortable all day without further electrical input. Other options to heat a home include forced-air heating, baseboard heating, gas burners, electric heating elements, space heaters, and passive solar design.
There are three types of radiant floor heating:
Air-heated radiant floors – Air cannot hold a large amount of heat, so this type of system is rarely installed. They are not cost-effective for residential use.
Electric radiant floors – This type of heating uses electric cables or electrically conductive plastic mats installed beneath the floor covering. It is cost-effective when used with flooring of significant thermal mass. Electric systems are cheaper to install than hydronic systems, but In the long run it would likely be less expensive to use a different fuel source and go with a hydronic system, which is powered by gas. This option is frequently used to retrofit a single room or to add a little luxury. This is common in bathrooms but can be ideal for a smaller home or for occasional use.
Hydronic radiant floors – The most popular and cost-effective type of radiant heating, hydronic radiant floor systems pump water heated from a boiler through tubing laid in a pattern under the floor. Manifold setup allows varied heating of different zones. This is ideal for homes that already use a water heater.
Underfloor heating pipes, before they are covered by the screed. – From: Wikipedia
Illustration of hydronic radiant floor heating system. – From: This Old House
Forced-air heat vs. radiant heat temperature distribution. Note the even gradient in the radiant heating system vs. the roundabout circulation of the forced-air system. – From: Uponor
At New Avenue, we’ve incorporated radiant floor heating in many of our projects. Here’s a short list of advantages and disadvantages of radiant floor heating:
Pros
One of the largest selling points is comfort. A warm floor allows you to more comfortably walk around barefoot.
Radiant floor heating is very quiet. There is no airflow through ducts as one would hear from forced-air heating systems, and there is no gurgling and little to no expansion and contraction creaking as one would hear from baseboard radiators.
For hydronic heating, a lower boiler temperature than one would need for baseboard heating increases boiler life and gives the option to use hot water heated by solar energy. This is difficult to permit, though, and it is often a DIY project.
Not having to configure a room for a baseboard radiator or air register gives occupants more flexibility in arranging furniture. The heating system is essentially invisible.
There is less dust circulating around the house than with forced-air systems. There are no surfaces that become too hot and burn dust as with electric baseboard systems.
This type of heating is good for when building occupants have acute chemical sensitivity or allergies. A forced-air system could distribute dust, and an electric heating element or gas burner can burn dust particles.
With a forced-air system, heated air rises up to the ceiling, then cools and sinks back down. A radiant floor system gives a more desirable temperature gradient throughout a room.
Cons
Radiant floor heating costs more to install than other types of heating, particularly for retrofits. Also, depending on your local climate, you may still need a separate air-conditioning system. You can expect to pay 50% more for installing a hydronic radiant floor heating system than for a conventional forced-air system. Costs have averaged $12-15 per square foot in projects we have managed.
High-performance green homes that need little heating energy would not benefit or would benefit very little from the added costs of putting in an expensive heating system. Other, less-expensive heating options can provide the same level of comfort, particularly when the building envelope already does a fine job.
There is a time lag of heat movement through the flooring. This can lead to an overheating problem if there are other sources, such as passive solar, already delivering heat to a space. It is probably best to disable or avoid installing radiant floor slabs where solar heat will already heat the air more directly.
To be effective, floor coverings must be thin and conductive. The covering should not insulate the heating system from the room. Ceramic tile is the most common and effective floor covering for radiant floor heating, but thin carpeting and wood can also be used.
Consistent heat may not be desirable for homeowners who like to turn their heat on and off at different times of the day.
While great for smaller rooms with lower roofs, in some cases it can be less energy efficient than forced-air heating. Check with a heating contractor to see if it would be sensible.
While it does cost more, radiant floor heating is a popular option. It provides so much more comfort than what many of us have experience with in older, drafty, or ineffectively heated homes. A well-operated radiant heating system with a programmable thermostat can save you hundreds of dollars on home heating bills. Also, many states have financial incentives for upgrading homes to boost energy efficiency. If you’re building a small home, this is something to consider.
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