Radiant space heating is an ancient but elegant concept. The Greeks and Romans were the first to realize that heat rises.  They put this theory to work by heating the floors of their bathhouses with fire. Now, 2000 years later, the principle still applies: the best way of warming a room is to heat the floor rather than to try to make heat travel sideways from a fireplace, radiator, baseboard heater or air register.
 

How does Hydronic Radiant Floor Heating work?
Hydronic Radiant Floor Heating differs from other types of Radiant Floor Heating because it uses heated water running underneath the floors to provide heat. A typical system consists of plastic tubes (PEX Tubing) laid within a floor that carries hot water into specific rooms or "zones", dispersing the heat through the floor.

The cool water returns to the heat source where it is reheated and sent out again in what is known as a "closed-loop system". The pipes can be encased in a concrete slab, a concrete or gypsum cement overpour, laid into thin grooved panels that nail on top of a subfloor, or suspended below a wooden subfloor using metal fins fastened under the floor surface. The heat output is determined by pipe spacing, water temperature, flow rate and floor covering. The heat output must be calculated to meet the heat loss demands of the home.

One type of tubing commonly used is a new leak-resistant, non-toxic, high temperature, flexible piping called cross-linked polyethylene (PEX). PEX is a durable tubing that doesn't become brittle over time and isn't affected by aggressive concrete additives or water conditions. PEX has been used in Europe since the 1970s and was introduced to North America in the early 1980s.

 

Advantages of Hydronic Radiant Floor Heating:

Unsurpassed in Comfort: To appreciate how comfortable radiant floor heating is, think of the way the sun warms you on a cool, windless day. Conventional systems depend on circulating warm air; radiant floor heating operates exactly like the sun - by emitting heat directly. 

Savings: Radiant floor heating is also less costly to operate because it creates a comfortable environment with less heating.  Conventional systems allow heat to collect where it’s most likely to escape at the ceiling and along outside walls. With radiant floors, the temperature throughout the room remains nearly constant. This factor alone reduces heat loss by up to 40% when compared to similar homes using conventional heating methods.

Free Solar Energy: Because radiant floor heating operates at such low water temperatures, it works especially well with active solar collectors! Our solar systems typically provide up to 50-70% of the energy required to heat the home. 

Lifespan: While the heat source(s) in a properly maintained system can last for as long as 20 years, the solar collectors have an expected life of 30-40 years and the PEX tubing set in the floor are expected to last more than 50 years. (Some test results indicate life expectancies of 200 - 300 years) 

Clean & Healthy: No drafts or fans stirring up dust, dirt, or other allergens in the air.

Noise Reduction: The system is quiet because the circulator pump, used to slowly move water, is nearly inaudible. The loudest sound in the system is usually the gas or oil boiler.

Flooring Options: Because radiant floor heating operates at such low temperatures, you can use almost any floor covering: wood, carpet, tile, marble, granite or vinyl. With carpet, the response time and efficiency of the floor will be slightly reduced, but the radiant floor will deliver the heat required to maintain a high degree of comfort.

 

More information about Radiant Floor Heating systems is available from the

US Department of Energy.