Whole house ventilation fan question

(Charles Hulbert) #1

Hello Folks as I was doing my mock inspections one of the houses had a whole house ventilation fan in the ceiling. That was blowing directly into the attic. The fan had louvers that would open and close when the fan was turned on and off but there was no ductwork in the attic for the fan. Should these fans be directed outside the attic? The same way a range hood or bathroom vent fan would be or is it Custom practice to let the attic ventilation deal with this added air movement.

(Marc A. Goldenberg, Inspector Lic # HI1365 Mold Assessor Lic #1) #2

For homes or buildings with a whole house fan, the hot air is pulled into the attic. Due to positive pressure, air in the attic is pushed out through the vents or gables. Simultaneously, negative pressure is created in the living area, which helps to draw cooler air in through the windows.

(Daniel Horton) #3

But you must make sure there is sufficient venting in the attic for all that forced air to exit the attic. Those fans push some serious cfm’s.
Too much positive pressure in the attic will start to push air back into the house through gaps and light fixtures.

(Charles Hulbert) #4

Thanks for the input