Radiant Floor Heat Brings Summer Home in Winter
Warm your toes with heat from the ground up with Beach Barrett.

Have you ever noticed how a house can feel cold in the winter even though the thermostat register reads 70 degrees? The air in the house may be 70 degrees, but this warm air is attempting to heat all of the surroundings to that temperature as well. Your walls, floors and ceilings are colder than the air is, and these surfaces are drawing heat away from your body.

However, if the whole floor is heated to 72 or 73 degrees, this large, warm surface, like a gentle heat lamp, will radiate heat to all the objects and surfaces in the room. They in turn radiate heat to you. The air temperature may only be 68 or less, but you will feel naturally warm - warm to the extent that you can walk around in bare feet and shorts like you would in the summer--perhaps even forget that it's winter outside!

Radiant heat operates via a warm water gently flowing through all your floors, quietly providing you with gentle all pervasive warmth. Radiant floor heat is not a new concept. However, it was not available in this country until about ten years ago. Today, almost every manufacturer in the hot water heating industry markets a line of radiant floor heating components. This system can be installed in walls and ceilings, but the most practical and effective approach is to install it in the floor.

The core of any radiant system is the tubing used to deliver the heat. Generally, it is 1/2 inch flexible plastic tubing that is laid out at 8 to 12 inch spacing below or in the floor. The tubing is made from a material called "pex" which stands for cross-linked polyethylene, an extremely tough and durable form of polyethylene that was developed in Europe about 35 years ago. This tubing is usually embedded in a concrete slab on ground level or in a 1.5 thick concrete layer on top of a wood floor. The concrete adds stability to the tubing and delivers the heat very evenly. Systems with tubing embedded in concrete are commonly known as "wet" installations. The tubing can also be suspended in the air below wooden floors or be stapled on top of the sub floor between nailers. This is commonly known as a "dry" installation. Putting a 1 1/2 inch layer of concrete on top of a wood floor adds both fireproofing and soundproofing properties to the structure and makes for anextremely solid floor.

The ultimate lifetime of the tubing is determined by many factors. Almost all tubing is guaranteed for 25 years, with a lifetime expectancy of 100 plus years. In wet installations, the tubing will last as long as the concrete surrounding it remains stable, which is usually the lifetime of the house itself. Tubing in dry installations should last the lifetime of the house as well, but since the tubing is not surrounded and supported by concrete it is more vulnerable to outside factors. The best insurance for guaranteed longevity is that the tubing is installed by a trained and experienced radiant floor contractor.

Recently a new form of tubing known as pex-al-pex has been developed that incorporates a layer of aluminum sandwiched between two layers of pex. The aluminum layer increases both the heat delivery properties and durability of the tubing. When radiant floor is installed in small areas such as a single bathroom or kitchen, electric heating wires can be embedded in the mortar below tile floors. This form of heating is more costly to operate, but is not objectionable for small rooms.

The warm water that is run through the floor can be heated by a gas, oil or wood boiler, a gas hot water heater, a ground source heat pump or an electric boiler. Today boilers are smaller, lighter, quieter and much smarter than the cast iron monsters of the past. These boilers use stainless steel or copper walls and operate at 95% plus efficiencies. They are usually a "sealed combustion" design which means that they do not consume any air from inside the house.

Another viable heat source is our the sun. Solar energy makes a perfect match with radiant floor heat. This is because radiant heat operates at a moderately low temperature. The lower the temperature at which a system operates, the more heat it can absorb from the sun. North Carolina has some of the best solar credits in the nation and when a solar system augments a heating system, the 35% solar tax credit is extended to the heating system as well.

In terms of efficiency, radiant floor systems are generally 20 to 30% more efficient than a similar forced-air system simply because forced-air systems must accumulate heat at the ceiling before it reaches the floor. Even when the heat does reach the floor, it is cooler. The result is cold feet and a stuffy head. Radiant heat is just the opposite, resulting in less waste, less noise, less dust and much more comfort.

Beach Barrett owns Thermacraft, a company specializing in the installation of radiant floors. He can be reached at 828-891-5707 or www.thermacraft.net.

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