"brian0918" wrote in message
oups.com...
We have central air, and the upstairs stays around 85+ (in 100%
humidity) despite the temperature downstairs staying at 75 or less (ie,
whatever the thermostat is set at). IThe upstairs has two fully-open
vents through which little air blows, and what appear to be 2-3 vents
for the warm air to exit. Can anything be done to help cool the
upstairs? The curtains/blinds are kept closed, and the door leading to
the upstairs is kept shut to prevent any warm air downstairs from
moving upstairs.

Also, attached to our air conditioning system in the basement is an air
cleaner that doesn't work, and when you remove the cover from that, a
ton of air is pulled in. I've noticed that this causes a lot more cold
air to be forced through the vents, substantially cooling the
upstairs. However, we asked someone who would know about these things,
and he said you shouldn't do that (for some reason). Any information?

We can't see your house from here, and I'm no HVAC expert. However, one of
the family homes we had when I was a kid had a similar problem, even though
the system was 'zoned', with 2 thermostats. Ended up with a 2nd smaller
furnace for upstairs, and splitting out the plenum. It all worked fine after
that.

I'd recommend paying a HVAC contractor, NOT the one named on the sticker on
the furnace, to come out and do an inspection and load calc for both floors,
and to balance and tweak the any baffles or valves in the ductwork. The air
cleaner sounds like a good place to start as something throwing the existing
air flow off balance. If opening the cover improves air flow to upstairs,
I'd suspect insufficent air flow from the returns on that floor. If the
cleaner doesn't work, and you don't miss it, probably simplest to have the
contractor rip it out and plate the hole over. (My furnace in my 'new' 1960
house, with original furnace, has a big plate on the side where something
like that used to be... Yes, a new HVAC is on the list, but the new roof
comes first.) Try leaving the stairway door open for a few days- if that
improves things, that means air return problems are real likely.

aem sends....