Q&A: winter heating systems.

Q: I am interested in having a radiant floor system installed. What ate the real benefits of radiant floor versus forced-air heating? Will the installation cost and running of the radiant heating really balance out against the cost of fuel?

Radiant floor heating systems are desirable for new construction as well as for retrofitted designs. One of the foundations of a comfortable home is the heating system that you choose. Radiant heating is best known for providing comfortable heat. There are many real benefits of radiant floor in comparison to forced-air heating systems. In addition to comfort, other benefits include higher efficiency, reduced operating costs, and elimination of unhealthy airborne particles.

In a radiant floor system, hot water is run through tubing underneath the floor surface that warms the floor and radiates heat to the space above. By heating the floor, a thermal inversion is created that traps cool air at the ceiling and circulates warm air in the living space.

The heat source in a radiant floor system is a condensing boiler, which is fueled by propane, natural gas, or oil. In comparison to traditional forced air heating systems, hydronic systems are more efficient, therefore reducing the amount of oil and propane needed.

Hydronic heating is an efficient heat distribution system that takes advantage of a whole floor space to provide heat to that space, as opposed to forced air blown out of a small space to heat a large space. Because it is laid out evenly under the floor space, hydronic heatIng provides continuous, perfectly uniform heating. Since radiant floor systems are evenly distributed under the entire floor space, the overall heating requirements are lessened. In a forced-air system, the heat rises quickly to the ceiling. In a radiant system, the floor serves as thermal mass by absorbing the heat that is provided. For this reason, the thermostat can be set two to four degrees lower than in a standard forced air system. The lower operating temperatures essentially are the heart of the efficiency of a radiant system. It allows for reduced fuel consumption, and typically saves twenty to thirty percent in heating expenses.

Installation costs of a radiant floor and forced air-heating systems ate virtually equivalent. For a three thousand square foot home, the average installation cost is four to six dollars per square foot for new construction. The reductions in operating costs, which are a direct result of the systems efficiency, are where the savings become evident.

A radiant floor heating system will save you money in the long-term in fuel savings. Integrating a solar thermal hot water system into the radiant design as a supplemental heat source will multiply savings. A solar thermal hot water heating system can be implemented into the radiant floor system, and can offset as much as eighty percent of propane, gas or oil requirements State and Federal Tax Credits are available for active space heating systems as well as for solar water heating systems, which again can be applied to the overall cost savings.

Hydronic heat provides health benefits as well. Radiant heat keeps the floor warm and dry, which inhibits the growth of mold and mildew. Forced-air systems circulate airborne particles including dust, pollen, mold, and allergens. A radiant system eliminates the need for blowers and vents that circulate these airborne particles.

In comparison to forced-air systems, radiant systems overall provide high efficiency, lower operating costs, increased health benefits, and higher levels of comfort.

Leslie Segal is the Marketing Director at Sundance Power Systems, a local provider of renewable energy and radiant floor heating systems, offering design and installation services. You can contact Sundance at 828-689-2080 or on the web at www.SundancePower.com.

Q: I have heard that our high efficiency insulation, combined with our passive solar design means that we don't have to invest a lot in heating the house through out the winter. Should we invest in radiant floor heating or stick with a forced-air system?

When deciding on what kind of heating system to install in your home, you must consider quite a few variables that affect the way the house will function.

A home's mechanical system is there to maintain the quality of the living space. This means heating, cooling and/or dehumidification, fresh air introduction, and filtering. While many homeowners choose not to install air conditioning, it is very important, especially in our climate, that the dehumidification aspect of it be considered. Fresh air is also necessary; most people do not keep doors and windows open in the winter.

Radiant floor systems are wonderful for those that don't like the feeling of air blowing throughout their house. These systems can also utilize the energy from the sun to pre-heat the water that circulates throughout the floors. But, they require a fuel (natural gas or propane) powered boiler to heat the water that warms the floors. The decision to install radiant floor systems is typically one based on the desire for warm floors, not efficiency. Because the heat is transferred via radiation, the integrity of the building envelope becomes very important.

Since radiant floor systems have nothing to do with air, another system will be needed to supply fresh air into the borne, filter the air in your living environment, and dehumidify the living space in the humid summer months. All of these items require some sort of air moving device. This separate system will add to your installation costs, and should be considered as part of the overall plan.

The better your building envelope is, the less energy your home will require to remain comfortable. If you have a poorly insulated and leaky house, then you will have to make a lot of heat all winter long. If you have a well insulated and tightly constructed house, then you won't need as much heat. With advanced insulation systems like Icynene, the size of the system you choose doesn't have to be as large. This won't affect the upfront costs too much, but the operational costs will be much less, due to decreased infiltration levels and reduced heat loss via conduction.

The size of the air conditioning part of the system is even more important than heating. If your air conditioner is too large, then it won't remove enough moisture from your living space. Since humidity is a large part of comfort and mold control in this climate, bigger is not better. If you are going to install a new heat pump this winter, you should pay close attention to the sizing of the cooling components.

Every home is different when it comes to sizing. Orientation, insulation values, type of windows, and infiltration levels all affect the home's need for energy. A "manual-J" load calculation can be performed to determine exactly how large the system should be. This computerized analysis takes all of these variables into consideration, resulting in a properly sized HVAC system.

Isaac Savage is president of Home Energy Partners, a Building Performance Contracting firm that is located in Asheville, NC. He can be reached at 828-350-1155 or on the web at www.HomeEnergyPartners.com.