I have a Tri-level home with two separate furnaces and air conditioning
units. One unit controls the lower two levels and another the upstairs
level. The lower unit has a thermostat located at the bottom of the
stairway leading to the upstairs, and the upstairs had a thermostat at
the TOP of those stairs.
Ever since I moved into this home (30+ years ago), I have had uneven
heat/cooling of the upstairs rooms. When the heat or cooling would go
on, the room temperature would be some 8-10 degrees different from what
the thermostat was reading. Eventually the thermostat would be effected
by the temperature change and would turn off the heat or AC. The only
problem was it ran much longer when it would come on, and the uneven
Recently I read that a thermostat should NOT be installed at the top of
a stairs. Obviously heat from the downstairs would tend to rise and
impact on the upstairs thermostat when cooling was taking place. The
question I have is why the uneven control while heating is taking place?
One would think that when the upstairs furnace was on, the stairs
would have little or no impact due to the heat rising up?
Finally I decided to do something about this uneven temperature
problem. I took a digital thermometer and looked for a location in the
same hallway upstairs that was more representative of the true
temperature. That is, much warmer than being sensed by the thermostat.
After relocating the thermostat some 10 feet away from the stairs the
temperature is much more even. I am very happy with the result.
My question is this: I can understand the impact of the stairway on
cooling the upstairs, but why did the heating of the upstairs respond
poorly as well? I feel I am overlooking something simple, since I know
it DOES impact it by the results I achieved.