Central Air Purification/Ventilation/Dehumidification Systems Strategy to promote occupant comfort and good IAQ  The Environmental Protection Agency (EPA) and their Science Advisory Board report that indoor air pollution is among the top five environmental risks to public health. EPA studies show that levels of indoor air pollutants can reach more than 100 times that of outdoor air pollutants. Indoor air pollutants such as dust mites, bacteria, and pollen come from almost everything in our homes including cleaning supplies, smoke, dust, molds, paint, carpets, drapes, upholstery, furnaces, gas burners, wood, and other building materials. Central air purification systems minimize the amounts of these small particulates in indoor air.
Central air purification/ventilation systems are added to the air handler of a conventional heating and cooling system. They draw indoor air directly into the unit, combine it with fresh outdoor air, and then direct it through a filtered outlet to the air handler supply above the refrigerant coil. The filter in the outlet is up to 95 percent efficient according to the American Society of Heating Refrigeration Air conditioning Engineers Dust Spot Test (a test to determine the effectiveness of a filter in capturing particulates). Too much moisture in the air can lead to condensation, which can promote mold and mildew growth. One air-purifying ventilator incorporates a dehumidifier into the system. During the heating season, because the dehumidification process heats the air going to the heating system coil, ventilation efficiency increases. 
 | Reducing moisture can enhance building material durability. |  | Improving indoor air quality improves occupant safety. |
The units are manufactured by Therma-Stor Products a division of DEC International, Inc., and distributed through many local suppliers.
The installed cost is usually between $2,000 and $2,500.
Operating cost will vary with outdoor conditions, air particle filter efficiency (there will be a higher pressure drop across a more efficient filter), and whether or not dehumidification is used (which adds to energy use). There is always an energy penalty with using outdoor air ventilation, because the incoming air must be heated or cooled.
There are no codes that restrict the use of these systems, but they must be installed in accordance with the residential mechanical codes. Some jurisdictions require the use of mechanical ventilation, but not purification or dehumidification.
Not Applicable
It is recommended that an HVAC contractor or builder install the unit next to the air handler or in the attic. It can be installed on new or existing equipment.
Therma-Stor offers a 1-year limited full product warranty and a 5-year limited warranty on parts of the product (condenser, evaporator, and compressor).
Ventilation systems help improve indoor air quality by reducing indoor air pollutants. People suffering from allergies may especially reap the benefits of cleaner air. Dehumidification can reduce mold and mildew and the associated musty smell. The dehumidifier unit is better suited for humid climates and the unit that does not dehumidify is best suited for dry climates. | 
