On Aug 13, 3:34*pm, "
wrote:
A friend has a house with two gas furnaces and AC.
The downstairs one is OK, the upstairs which is based
in the attic is very marginal at best. *The biggest problem
is that there is not enough air flow. *It's really only a
problem in AC season, when it takes a very long time to
cool. *It has to run most of the day just to keep it at
85.

It would appear that
is due to a number of factors. * The way they did the
ducting is far from optimal. *Right off the furnace the duct
makes two 90deg turns, then feeds down a long duct off
of which come flex hoses that feed 5 bedrooms and two
baths. *The furnace is located close to one long side of
the house. *Three of those supply hoses have to go
up close to the peak of the roof, going across to the
other side of the house. *They did that to avoid going
straight across the attic floor, leaving space for walk-in
accessibility, which is good, but it comes at a cost.
The return ducting is good. *The AC itself appears to
be working, the air coming out is 15 deg cooler than
going in, closer to 20 deg right at the unit.

So, looking at this, I can see some possible improvements.
Obviously doing something with the ducting would be
beneficial. *But I also looked at the blower and right now
it's a 1050 RPM 1/3 hp. *I'm thinking part of the solution
could be to go to a 1650 RPM, 1/2 hp, which should be
a drop in replacement. * I know it's not a total solution, but
even if the ducting stuff is straigtened out, given the length
of the runs, etc, I think having the more powerful blower
would still be part of the solution. *Being that the blower
motor is easy and cheap to do, I wonder if it makes sense
to just try it and see how much it helps?

But what size are the supply hoses, I asked about that before?? Is
the problem low flow of very cold air, insufficient coldness of lots
of air, or something in between???