Radiant Heat Floors

Radiant Floor Heat is an incredibly comfortable method of heating. Unlike heating the air as most heat systems do, radiant heat systems heat the floor and building structure so that you feel enveloped in warmth. It’s effects are even more dramatic when it is combined with concrete or another high thermal mass material or structure.  Because of feeling the heat directly from the floor, you feel warmer, and most people will find that they are able to use a lower thermostat setting, thus saving energy. People and pets find they are comfortable at a lower ambient air temperature when standing (or laying) on a warm surface. (see article) Understanding the different forms of heat transfer will help you understand radiant heat.

 

Radiant floor heat can be installed different ways depending on the type of structure and the phase of construction in which it is installed. In-slab installations are the most simple from a labor standpoint, but they must be planned ahead and installed before the  slab is poured. Picture 1. shows the tubing layout prior to concrete being poured. As with wood frame floor installations, a system can also be installed underneath an elevated slab. The Schmidt House in Athens GA has a hydronic radiant heat system installed underneath it’s 2nd story slab (see picture 2.)

 

Radiant heat floor systems can also be installed with wood frame floors either underneath the sub-floor in between the joists, or on top of the sub-floor beneath the finished floor. These systems are often referred to as dry system installations (because they don’t have wet concrete poured around them.) When installed underneath the floor, the tubes are simply stapled to the bottom of the sub-floor. When installed on top of the sub-floor several methods can be employed. The tubing can be stapled directly on top of the sub-floor as we did in a remodel job where we were finishing an attic that already had a finished ceiling below. In this case we shimmed between the tubing. This provided a surface on which to nail the finish floor (see pictures 3 & 4.) Another method is a manufactured panel system that is laid on top of the sub-floor, (or another system that is actually used as the sub floor.) The panels have pre-routered grooves in which the tubing is placed. The grooves allow the tubing to be below the surface of the panel and the finished floor is attached directly to the panel.

 

Once the tubing is installed it is brought back to a central location where it is connected to the distribution  system and heat source as shown in picture 5.

 

5. A Radiantec manifold system where the heating tubes are terminated. This system services two floors with four piping loops on each floor. The two pumps (red) pull heated water from the water heater and push it through the tubing in the floors. The heated water looses heat (thus warming the floor) and is returned to the water heater to be reheated.

A solar space heating system is made up of these radiant heat manifolds which are connected to a solar water heating system. The two large solar heat exchange tanks with electric back up are the heat source for the floor system and the household hot water.