Joseph Meehan wrote:
A. Pismo Clam wrote:
Yes! We are attempting to keep the attic as cool as we can, Joe.


Do you want to keep the attic cool because you want the attic cool, or
because you want to protect the roof or because you want to keep the living
areas below the attic cool?

For two of the four, passive ventilation along with good insulation
works very well. With proper insulation between the attic and living area,
there is very little to gain by reducing the attic temperature using power
vents and you add operating cost, vibration and maintenance.



Although your suggestion there is little benefit to power venting an
attic if the purpose is simply to cool it, many homes have the furnace
and air handler installed in the attic. I have such a home, and the
impact of keeping the attic temperature lower so as to minimize the
impact on the cooling coil can be dramatic. My home has gable ends with
a power vent in two gables. There is also another gable for air intake
along with several eave vents.

On one summer day I wondered what effect the power vents had on the
attic temperature and placed a remote thermometer in the attic so as to
observe it with the vents on and off. The temperature was easily
lowered in excess of twenty degrees when the vents were turned on. I
say easily, because I watched the temperature for only about 30 minutes.

Now twenty degrees might not seem like much, but keep in mind the sheet
metal of the furnace/air handler (and the cooling coil inside) along
with the metal ductwork are fighting the effort to cool the air inside
them. I just thought I would share this fact in case the OP had a
similar situation.