Balanced Ventilation Fan

Balanced Ventilation Fan
Balanced ventilation systems, if properly designed and installed, neither pressurize nor depressurize the structure. Instead, they give in and expel approximately equal amounts of fresh outdoor air and polluted indoor air.
Balanced Ventilation Fan Advantages
A balanced ventilation system usually has two fans and two ductwork. Fresh air supply and exhaust vents can be installed in any room, but a typical balanced ventilation system is designed to supply fresh air to bedrooms and living rooms where users spend the most time. It also expels air from rooms where humidity and pollutants occur most often, such as kitchens, bathrooms and laundry rooms.
Some designs use a single point exhaust and because they supply the outside air directly, balanced systems allow filters to be used to remove dust and pollen from the outside air before feeding it into the house. Balanced ventilation systems are also suitable for all climates.
Balanced Ventilation Fan Disadvantages
Balanced ventilation systems, such as both supply and exhaust systems, do not soften or dehumidify the make-up air before it enters the house. Therefore, they can contribute to higher heating and cooling costs, unlike energy recovery ventilation systems. Similar to supply ventilation systems, outside air may need to be mixed with indoor air prior to delivery to prevent cold drafts in winter. Because they require two duct and fan systems, balanced ventilation systems are often more expensive to install and operate than supply or exhaust systems.

Energy recovery ventilation systems provide controlled ventilation of the house while minimizing energy loss. They reduce the costs of heating the ventilated air in winter by transferring the heat from the hot indoor exhaust air to the fresh (but cold) outdoor supply air. In summer, the air inside cools the warmer supply air to reduce cooling costs.
There are two types of energy recovery systems: Energy Recovery Ventilators (ERVs) and Heat Recovery Ventilators (HRVs). Both types contain a heat exchanger, one or more fans to move air through the machine and controls. There are some smaller wall- or window-mounted models, but most are central, whole-house ventilation systems with their own ductwork or shared ductwork.