Research

Radiant Floor Systems

U.S. Dept of Energy,  Renewable Energy

The following came directly from the U.S. Dept of Energy web site:

Types of Radiant Floor Heating

• There are three types of radiant floor heat: radiant air floors (air is the heat carrying medium); electric radiant floors; and hot water (hydronic) radiant floors. All three types can be further subdivided by the type of installation: those that make use of the large thermal mass of a concrete slab floor or lightweight concrete over a wooden subfloor (these are called "wet" installations); and those in which the installer "sandwiches" the radiant floor tubing between two layers of plywood or attaches the tubing under the finished or subfloor (dry installations).
• Because air cannot hold large amounts of heat, radiant air floors are not cost-effective in residential applications, and are seldom installed.
• Electric radiant floors are usually only cost-effective if your electric utility company offers time-of-use rates. Time-of-use rates allow you to "charge" the concrete floor with heat during off-peak hours (approximately 9 p.m. to 6 am). If the floor's thermal mass is large enough, the heat stored in it will keep the house comfortable for eight to ten hours, without any further electrical input. This saves a considerable number of energy dollars compared to heating at peak electric rates during the day.
• Hydronic (liquid) systems are the most popular and cost-effective systems for heating-dominated climates. They have been in extensive use in Europe for decades. Hydronic radiant floor systems pump heated water from a boiler through tubing laid in a pattern underneath the floor. The temperature in each room is controlled by regulating the flow of hot water through each tubing loop. This is done by a system of zoning valves or pumps and thermostats.

Concrete Network.com

http://www.concretenetwork.com/concrete/radiantfloorheating/

Provides an extensive listing of questions and answers relating to radiant floor heating.

Wirsbo

www.wirsbo.com

The following came directly from their web site:

• At Uponor Wirsbo we are committed to providing exceptional Life, Safety and Comfort Systems. Our quality Radiant Systems can deliver comfort and efficiency beyond compare.  Aquasafe is a clean, quiet and healthy plumbing system for your home and Aquasafe combines our plumbing system with fire sprinklers giving you fire protection and peace of mind.
• Free Advice on Radiant Floor Heating Free advice on buying and repairing radiant floor heating from leading authority and Home and Garden TV personality, Don Vandervort.