supply ventilation fan

 supply ventilation fan
supply ventilation systems use a fan to pressurize a structure, forcing outside air into the building while air leaks out of the building through vents, bathroom and ajar fan ducts, and deliberate vents (if applicable).
like exhaust ventilation systems, supply ventilation systems are relatively simple and inexpensive to install. a typical supply ventilation system has a fan and duct system that delivers fresh air, usually one, but preferably several, rooms that are most occupied by residents, such as bedrooms and living room. this system may include adjustable window or wall vents in other rooms.
 supply ventilation fan advantages
supply ventilation systems provide better control of the air entering the house than exhaust ventilation systems. supply ventilation systems pressurize the home, minimizing external pollutants in the living area and preventing the withdrawal of combustion gases from fireplaces and appliances. supply ventilation also allows outside air supplied to the house to be filtered to remove pollen and dust or dehumidified to provide humidity control.
supply ventilation systems work best in hot or mixed climates. because they pressurize the home, these systems have the potential to cause humidity problems in cold climates. ın winter, the supply ventilation system causes warm indoor air to leak through random openings in the exterior wall and ceiling. ıf the indoor air is humid enough, moisture can condense in the attic or on the cold outer parts of the exterior wall, causing mold, mildew, and rot.
 supply ventilation fan advantages
like exhaust ventilation systems, supply ventilation systems do not soften or dehumidify the make-up air before it enters the house. thus, they can contribute to higher heating and cooling costs compared to energy recovery ventilation systems.

because air enters the house from separate places, outside air may need to be mixed with indoor air before delivery to prevent cold drafts in winter. ın-line duct heater is another option but increases operating costs.
balanced ventilation systems, if properly designed and installed, neither pressurize nor depressurize the structure. ınstead, they give in and expel approximately equal amounts of fresh outdoor air and polluted indoor air.