First off - thanks to all for the comments and suggestions. I finally
found my papers from when we bought the house and got ahold of the man
who did the inspection. He's very knowledgable about this stuff and he
assures me that if I do what I planned on doing - the attic will drop
in temperature. This will in turn will allow the heat pump to work
better since it's ductwork is in the attic. The end result will be a
more comfortable bonus room, a heat pump that does not run as much, and
if I'm lucky, an attic that's cool enough so I can use it to store more
then just 'hardy' stuff. His reasoning is the R-factor of the ductwork
insulation, and the differential between the outside air temp and the
attic air temp. He went off on a bunch of stuff about BTUs, and such,
which I didn't understand, but since he was helping me for free, I was
polite and let him go.
to recap - I have 8 or so static vents on a tall peaked roof, that
offer little help in moving the HOT air out of my attic, so I'm
planning on replacing 2 of them with powered vents. there is a small
heat pump in the attic which serves the ajoining bonus room, which is
over the garage.
Right now, the bonus room is always warm and the heat pump comes on
very frequently, runs for 5 minutes, cools the bonus room down
somewhat, then shuts off, only to come back on again in another 10
minutes or so.
His only cautions were:
a) make sure the soffitt vents are clear (easy to tell by turning out
the attic light and look for daylight).
b) cover up all the remaining static vents except for one or two - the
furthest away from the power vents I install.
I have a contractor coming next week to do the work and will report
back the results - hopfully GOOD results. Yesterday the temp reached
112 degrees F in the attic.