We just purchased a new (older) home, and have no familiarity with the whole-house fan installed in it. When ours is running, air can be felt coming out of just about every crack in the house...outlets, baseboards...even wall cavities opening to the basement !!! Also, when the attic door is opened, hot air comes rushing in, and the fan, normally quite noisy (the automatic grill vibrates), quiets down considerably.
It seems as though the attic vents, one in each gable end, are not adequate to expel all the air the fan is trying to force into the attic space. Is this a good guess, or is there supposed to be a certain amount of attic air pressure when the fan is operating? Should we add more vents, gable, ridge, or whatever?