Understanding how a home cools and some simple tips.

“My second floor is so much warmer than my main floor, basement is so cold, air conditioner runs for long periods.

If you find yourself making these statements during the summer season your system is probably deficient in some way(s).

First let’s understand for many homes air conditioning is an add on installed sometime after to the existing HVAC system was initially designed.  The system most likely being designed for heating, even in many of today’s new homes little care is given to proper duct design, installation and change in season requirements.

Warm air rises (lighter) and cold air falls (heavier), understanding this simple effect you can move to the next step.

Your home upper ceilings will have the hottest air (upwards of 90+f in the summer) and your basement floor the coldest. For your cooling system to work effectively and efficiently you should be taking the warmest air and cooling that air through your air conditioning system not the coldest air and making is colder. This removes hot air allowing cool air to rise and will give you a more efficient system and comfortable home.

Return air opens (the one’s that suck in) are the key to solution for all the above statements. 

Let’s take an example:

Two-Story Home:

Second floor is 5-6 degrees warmer in the afternoon than the main floor and the basement is cold. The home was designed for heat with cold air returns located at the base of the walls on the main floor, one return air on the second floor also at the base of the wall and one located in the basement. The air conditioner is correctly sized for the home and fan speed is properly set.

Summer comes around and on goes the air conditioner, firstly air will take the path of least resistance on a poorly designed/installed system, the basement return air drawing more air in than the main floor and very little to non on the second floor.  The basement has much colder air than the main floor and the second floor. So the mixed air gets cooler running through the air conditioning system which is making it heavier and it will fall to the basement faster and get the basement much cooler and so on and so on.

The system will run until the main floor is satisfied as that is where the thermostat is located, the basement feels like the inside of a Coleman cooler and that sleeping area upstairs is sticky and hot.

The Fix is in!

So, what can be done, if you do have return air(s) on the second floor remove the grille and see if the stud cavity is open upwards to the ceiling (a cell phone camera is great for this). If the cavity is open, you can easily cut another return air opening about 6” from the ceiling and put a grille on it.


Now to ensure its working and/or get it working. Take a trip the closest bathroom and grab one square tissue of toilet paper. This high-tech tool is how you will test the return is working.

Place the tissue on the new return air grille opening and it should easily stick to it when you let go. If it doesn’t stick here’s what you should do.  Close any return airs in the basement 100%, on the main floor start to close off those return air(s) also; until the tissue firmly sticks to the grille on the second floor.  NOTE: You can purchase large fridge magnet sheets from Michael’s Craft stores that will attached to metal return grilles simply.

Important we do not want to shut all the lower returns off on the main floor if you only have one return on the second floor as the new return air will not be able to pull enough air through it to serve the air conditioner needs and the grille will also make a noise like a swarm of bees and you wont sleep.  

Last peace of house keeping, we recommend running a fan continuously during the summer on two story homes to provide balance. Air conditioners should not just run for five minutes a run time of 15-20 minutes is normal on a home that is already at the comfort settings. Short running air conditioning system will often give your a cool damp home and no one wants that. 

Now that you have a properly working return air(s) on the second floor sit back and finally enjoy the summer in your entire home. Just remember to reverse the system in the winter as we want to take cold air and make it warmer.

If all the above seems to be too much, call us we can take care of this for you.



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