So-called radiant floors have an excellent reputation. Many customers report that this type of heating system is comfortable and quiet. Moreover, some suppliers of radiant floor materials and equipment claim that these systems can save energy.
In spite of the purported benefits of this type of heating system, few green homes include a radiant floor heating system. This article will explore why.
We’ve all seen ads for this type of heating system, including photos showing a barefoot mom watching her baby crawl across the floor. Using photos like this as a guide, is it possible to describe the heat transfer mechanisms in such rooms?
The mother’s bare feet are being heated by conduction. The air near the floor is also being heated; as the warm air rises to the ceiling, it creates a convective loop. So the room is being heated by convection. And, if the floor is warm enough, the mother’s bare arms are being heated by radiation.
In other words, all three heat transfer mechanisms are at work. So why is this a “radiant floor”? The phrase “radiant floor” is misleading, and should be abandoned. It’s more accurate to say that this floor has “in-floor hydronic tubing.”
There are three types of heated floors:
A hydronic heating system has a boiler rather than a furnace. (Boilers heat water, while furnaces heat air.) While most hydronic systems distribute heat using fin-tube baseboard units or wall-mounted radiators, some use in-floor hydronic tubing.
It’s also possible for a hydronic heating system to use a water heater rather than a boiler to heat the water.
The main disadvantage of hydronic heating systems is that they don’t provide a convenient way to integrate air conditioning. (Most air-conditioned homes in the U.S. use ductwork to distribute cool air; since…