Goedjn wrote:
All,

Looking for advice on a home heating/cooling problem, here's the story:

We have a two story house (2100 sq ft, almost equally distributed up and
down) in central Texas (mild winters, somewhat hot summers). Lennox
single 4 ton HVAC unit roughly 7 years old, single zone system. Summers
aren't bad, although the upstairs rooms are a bit warmer than downstairs
- nothing too unpleasant. Although two rooms (that face south and are
over a two car garage) get pretty warm in the morning & afternoons.
Winters on the other hand are completely different. The downstairs is
consistently 10-15 degrees colder than upstairs. It's almost unusable
on colder (30's) nights. We've tried small space heaters downstairs,
but they really don't help much.


Putting a door at the top or bottom of the stairs to
restrict airflow will keep more of the heat on the ground floor,
and more of the cool on the top floor. After that,
it's just a matter of putting the heat or cold where it's
needed. If you can't block the between-floors
airflow, then you need some way to deliberately circulate
the air between floors, which should even out the temps.

Insulating and plugging leaks would reduce your
total climate-control load, but it's sounds like
balancing is your current issue.

Multi-zone systems are for when you want to
reduce the load further by NOT controlling
the temperature in unused spaces.

I got a noticeable improvement by blocking off my downstairs *return*
vents. This forces the AC to pull the hotter upstairs air and cool it
off. Since you have two returns you could try this by covering the
downstairs return with cardboard. If it works then you make a more
attractive cover. I plan to block off my upstairs returns in the
winter to improve the heat circulation.

Caution: Some of the HVAC techs have posted about the possibility of
freezing your a-coil due to reduced airflow. This is supposedly not a
problem with blocking a return but it is my CYA notice.