Three balanced airflow ventilation devices were evaluated, an exhaust and supply fan (E&SF), air-to-air heat exchanger (ATAHE), and exhaust air heat pump (EAHP), which can be used increase the ventilation rate in an R-2000 (tightly constructed) type house.

A prototype of the EAHP, which uses a combination of heat pipe and heat pump, was built and tested.

A frosting and nonfrosting version of the EAHP were evaluated. The nonfrosting version provided the best overall performance. The capacity of the nonfrosting unit, using an additional 1 kW electric resistance heater at low outdoor temperatures, ranged from 7500 Btu/h (2.2 kW) at 59 F (15°C) outdoor temperature to 13400 Btu/h (3.93 kW) at -13 F (-25°C). coefficient of performance (COP) of the nonfrosting unit (including the electric resistance heater at low outdoor temperatures) had a maximum of 4.8 at 14 F (-10°C) and a minimum of at -13 F (-25°C).

Units: Dual