Central air in a 3-story house?

Question

My central air system cools the first two floors, but not the third. The problem is when there is a heat wave- cooling the second floor means freezing out the first. Is it OK to close the vents on the first floor to allow the cool to go up and then sink back down. Or would this interfere with the air flow and efficiency of the air conditioning unit?

Answer 1

Relocate the thermostat to the top or second floor. To solve your problem, I would recommend installing a smaller c/a or heat pump with separate thermostat for the top floor with a roof ventilating fan also. This will take the load off the main unit and extend its life, You will also be able to keep the lower floor thermostat at a higher setting. The electric bill should be much lower, offsetting the cost of the new unit. The utility company will usually have good payout figures for this type of project.

Answer 2

Multi-level homes are always a problem to cool, more so than heating. I would assume the thermostat is on the first floor. It only is concerned with the temperature at that point. Therefore, you must fool the thermostat by dampering down the areas closest to the thermostat. This causes air to travel to other areas where it is needed.