Habitat for Humanity - Schenectady: Schenectady, NY

• To record installation issues and evaluate the energy consumption and performance of radiant floor heating compared to forced-air heating
• To identify performance issues such as occupant comfort, thermostat set-point, thermal distribution, and temperature stratification within rooms
• To document cost, construction, and code-related issues of air admittance valves (AAVs)

Radiant Floor Heating – Dry System Hydronic

• It was extremely difficult to find a small-capacity, high-efficiency, moderately priced boiler or furnace for a tightly-constructed, energy-efficient home.
• A cast iron boiler in combination with a dry hydronic heating system is more sensitive to oversizing than a furnace in a ducted, forced-air heating system.
• There was no significant difference in energy consumption between the two heating systems when the data was normalized to adjust for the different operating efficiencies of the systems and basement temperatures, e.g., when the boiler’s operating efficiency was equivalent to that of the furnace (90 AFUE) and when the boiler was given “credit” for the 3o F higher basement temperature maintained by the system.
• The occupants felt that the radiant floor heating system was more comfortable than the forced air system, especially the warm floors.
• The installed cost of the radiant floor system was nearly double that of the forced air heating system.
• Room air temperature stratification was less for the radiant floor system than the forced air system. The radiant floor system showed a lower temperature differential between sensors located high (7 feet from the floor) and low (1 foot from the floor) on each floor. Average differential was 0°F on the first floor and 1°F on the second floor with the radiant system; 1°F on the first floor and 3°F on the second floor for the forced air system.
• Temperature distribution throughout the home was more uniform with the radiant heating system than with the force air heating system. Evaluating daily average temperatures taken at 8 locations, on average, the difference between the maximum and minimum was 3°F for the radiant system. For the forced air system, the difference was 6°F.
• The homeowners preferred the radiant flooring system and chose the radiant flooring system at the conclusion of the study.

Air Admittance Valves (AAVs)

• AAVs saved costs over conventional venting system due to reduced material needs.
• Code officials and plumbing contractors remain skeptical of AAV reliability.
• The use of AAVs is more advantageous in larger home with longer vent runs.