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?

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?

What diameter are the supply hoses, and I hope they are insulated???!!!

On Monday, August 13, 2012 1:34:50 PM UTC-7, 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?

Just one question: When you or your friend says that “the upstairs which is based in the attic is very marginal at best” do you have the downstairs on? What I mean is: Are you considering the house as a whole before you make your judgment? In other words: If you don’t have both the downstairs AND the upstairs air conditioner on at the same time the hot air is simply going to rise and make the upstairs hot.

On Aug 13, 4:37*pm, "hr(bob) "
wrote:
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?

What diameter are the supply hoses, and I hope they are insulated???!!!- Hide quoted text -

- Show quoted text -

Yes, they are insulated as is the rectangular duct
itself. I didn't measure the duct, but I'd say it's
about 20 x 10? The furnace is horizontal. The
crazy thing, IMO, is that they could have come
straight off the top of the furnace, ie in the direction
the air is already moving. Instead they did two
90 deg turns before starting the long straight run
across the attic. Near the end, it gets reduced down
to another duct about half the size.

I should also point out with regard to upping the
blower that right now it's two speed. So the 1050 rpm
speed is for cooling, heating is the lower speed,
maybe 750? I found an equivalent motor that is
3 speed, 1650. So, could use 1650 for the AC,
the lowest speed, which is probably 1300 or so
for the heat. Could also use 1300 or 1450, etc
for cooling if the 1650 doesn't work out for some
reason, eg noise?

Jus thinking if this quick, easy and cheap solution
makes a big improvement, maybe could avoid
screwing around with the ducting? Another thing
that sucks, IMO is that they put the furnace near
one end of the area it serves. They could have
positioned it another 10 ft or so towards the center
of the area it serves.

On Aug 13, 4:49*pm, wrote:
On Monday, August 13, 2012 1:34:50 PM UTC-7, 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?

Just one question: When you or your friend says that “the upstairs which is based in the attic is very marginal at best” do you have the downstairs on? What I mean is: Are you considering the house as a whole before you make your judgment? In other words: If you don’t have both the downstairs AND the upstairs air conditioner on at the same time the hot air is simply going to rise and make the upstairs hot.- Hide quoted text -

- Show quoted text -

The downstairs is at like 77F, which is a comfortable
temp. But you have a point. If the downstairs was set
to 72, it would probably make the upstairs a lot more
manageable. I forget the exact split, but as I recall
the total AC is like 5.5 tons, no more than 6 for sure,
with it split 60/40, the 60 being the downstains. The
house is 4100 sq ft. Another
thing that sounds kind of dumb, no? I'd put more of
the AC capacity up top.

The sad thing is the house is like 7 years old and this
isn't rocket science. You would think by now they
would be able to do this right.

On Mon, 13 Aug 2012 14:00:50 -0700 (PDT), "
wrote:




I should also point out with regard to upping the
blower that right now it's two speed. So the 1050 rpm
speed is for cooling, heating is the lower speed,
maybe 750? I found an equivalent motor that is
3 speed, 1650. So, could use 1650 for the AC,
the lowest speed, which is probably 1300 or so
for the heat. Could also use 1300 or 1450, etc
for cooling if the 1650 doesn't work out for some
reason, eg noise?

Jus thinking if this quick, easy and cheap solution
makes a big improvement, maybe could avoid
screwing around with the ducting? Another thing
that sucks, IMO is that they put the furnace near
one end of the area it serves. They could have
positioned it another 10 ft or so towards the center
of the area it serves.


It may help, but it may not. Sure, it will move more air, but if the
unit does not have the capacity to removed the heat from it, the
faster blower just moves warm air faster.

Have you checked the temperature drop over the coil? That will tell a
lot.

The often neglected aspect of low air flow, is return air ducts. Often under
sized.

With 5.5 tons for 4000 sq feet, seems like it ought to cool. Please have a
HVAC pro come out. He should clean the outdoor units with foaming chemicals,
run till they dry and then check the freon. And a few other checks. If your
system needs maint, you may have 5.5 tons of equipment, but not be getting
that much cooling.

I worked on a house, couple years ago. The guy was stuck on "if it's got 3.5
tons and not cooling, we need 5 tons or six". Several lack of maint problems
were there, and he was getting nearly no cooling. I repaired the system,
and life improved a lot. SWMBO was pleased, too.

Christopher A. Young
Learn more about Jesus
www.lds.org
..

wrote in message
...

manageable. I forget the exact split, but as I recall
the total AC is like 5.5 tons, no more than 6 for sure,
with it split 60/40, the 60 being the downstains. The
house is 4100 sq ft. Another
thing that sounds kind of dumb, no? I'd put more of
the AC capacity up top.

On Aug 13, 6:29*pm, "Stormin Mormon"
wrote:
The often neglected aspect of low air flow, is return air ducts. Often under
sized.

With 5.5 tons for 4000 sq feet, seems like it ought to cool. Please have a
HVAC pro come out. He should clean the outdoor units with foaming chemicals,
run till they dry and then check the freon. And a few other checks. If your
system needs maint, you may have 5.5 tons of equipment, but not be getting
that much cooling.

I worked on a house, couple years ago. The guy was stuck on "if it's got 3.5
tons and not cooling, we need 5 tons or six". Several lack of maint problems
were there, and *he was getting nearly no cooling. I repaired the system,
and life improved a lot. SWMBO was pleased, too.

All that is good, but if there is very limited air coming
out of most of the registers, not just very little cold
air, but very little air period, then I don't see how anything
maintenance related is going to do squat. It has an
electrostatic type filter and it's clean.

On Mon, 13 Aug 2012 16:38:41 -0700 (PDT), "
wrote:

On Aug 13, 6:29*pm, "Stormin Mormon"
wrote:
The often neglected aspect of low air flow, is return air ducts. Often under
sized.



All that is good, but if there is very limited air coming
out of most of the registers, not just very little cold
air, but very little air period, then I don't see how anything
maintenance related is going to do squat. It has an
electrostatic type filter and it's clean.




But, as Chris points out, if the inlet is restricted, the outlet won't
have an air to move. Do check that part if you have not already.

On Monday, August 13, 2012 4:38:41 PM UTC-7, wrote:
On Aug 13, 6:29*pm, "Stormin Mormon"

wrote:

The often neglected aspect of low air flow, is return air ducts. Often under

sized.



With 5.5 tons for 4000 sq feet, seems like it ought to cool. Please have a

HVAC pro come out. He should clean the outdoor units with foaming chemicals,

run till they dry and then check the freon. And a few other checks. If your

system needs maint, you may have 5.5 tons of equipment, but not be getting

that much cooling.



I worked on a house, couple years ago. The guy was stuck on "if it's got 3.5

tons and not cooling, we need 5 tons or six". Several lack of maint problems

were there, and *he was getting nearly no cooling. I repaired the system,

and life improved a lot. SWMBO was pleased, too.



All that is good, but if there is very limited air coming

out of most of the registers, not just very little cold

air, but very little air period, then I don't see how anything

maintenance related is going to do squat. It has an

electrostatic type filter and it's clean.

I have had to work on air conditioners where the previous residents had operated them without an air filter causing the evaporators to become clogged with dirt. I know the answer to this but I’m going to ask it anyway. Do you have an access panel or door on your evaporator coil that you can check from? Air conditioner installers never put one on residential units but always put one on commercial ones for some unknown reason. You will need to install an access panel or door and you need to do it without cutting the soft copper refrigerant lines while doing it.

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???

wrote in message
...
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?


Unfortunately the horsepower required to turn the same blower at the faster
speed varies as the cube of the speed ratio. Depending on where the system
restriction curve falls on the blower performance curves, 1/2 HP probably
ain't gonna get it.

On Mon, 13 Aug 2012 13:34:50 -0700 (PDT), "
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?

Check the RA vs supply dimensions. Works much better if RA can hancle
about 10% more volume than supply.
I had a similar problem a few years back with geothermal units.
Downstairs unit for 2,800 sq. ft. was great. Upstairs unit (1,800 sq.
ft.) had problems similar to what you describe. It turned out that the
upper unit had insufficient return-air. Additional RA vents added,
problem solved. That was 16 years ago.

Oft neglected, because people don't see how under sized returns could
"possibly" affect the air out put.

Christopher A. Young
Learn more about Jesus
www.lds.org
..

"Ed Pawlowski" wrote in message
...
On Aug 13, 6:29 pm, "Stormin Mormon"
The often neglected aspect of low air flow, is return air ducts. Often
under
sized.

But, as Chris points out, if the inlet is restricted, the outlet won't
have an air to move. Do check that part if you have not already.

That's true, a dusty and dirty evaporator would reduce the air flow. And,
you're right not to cut the copper tubing.

Christopher A. Young
Learn more about Jesus
www.lds.org
..

wrote in message
...

I have had to work on air conditioners where the previous residents had
operated them without an air filter causing the evaporators to become
clogged with dirt. I know the answer to this but I’m going to ask it anyway.
Do you have an access panel or door on your evaporator coil that you can
check from? Air conditioner installers never put one on residential units
but always put one on commercial ones for some unknown reason. You will need
to install an access panel or door and you need to do it without cutting the
soft copper refrigerant lines while doing it.

On Aug 14, 1:15*am, "Rick" wrote:
wrote in message

...





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?

Unfortunately the horsepower required to turn the same blower at the faster
speed varies as the cube of the speed ratio. Depending on where the system
restriction curve falls on the blower performance curves, 1/2 HP probably
ain't gonna get it.- Hide quoted text -

- Show quoted text -

That's interesting. I figured it would go up, but
wasn't counting on that much! Fortunately the sub
motor is 3 speed and the lower speed is probably
1300 rpm or so. Maybe that will be OK at 1/2hp

On 8/14/2012 7:42 AM, wrote:
On Aug 14, 1:15 am, wrote:
wrote in message

...





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?

Unfortunately the horsepower required to turn the same blower at the faster
speed varies as the cube of the speed ratio. Depending on where the system
restriction curve falls on the blower performance curves, 1/2 HP probably
ain't gonna get it.- Hide quoted text -

- Show quoted text -

That's interesting. I figured it would go up, but
wasn't counting on that much! Fortunately the sub
motor is 3 speed and the lower speed is probably
1300 rpm or so. Maybe that will be OK at 1/2hp

Is it actually running at 1/3 HP now? (Amp clamp and compare rated
current.) (Current versus hp is not particularly linear; watts vs hp
probably is.)

Don't remember it coming up (and way too obvious) - air filter is not
clogged?
Dampers not closed? (particularly to farthest run).

On Tue, 14 Aug 2012 06:42:12 -0700 (PDT), "
wrote:

Air flow in vents is hard to figure. I've got one room closer to the
furnace than others, same size vents, but it's always cooler in the
wintertime.
If the A/C is putting out the BTU's for the entire house, but the air
can't get upstairs, I'd look into booster fans. They sell vent
boosters and in-line boosters. Might be the more cost efficient way.

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Vic