Cooling a multi-story house is always complicated because the upper level ends up being hotter than the lower level. This is understandable if you consider that hot air is less dense than cold air. Fortunately, you can use the following tips to enjoy comfortable temperatures on both floors of your two-story house.
Use a Zoned AC
If you want to install or upgrade an AC, then the new system should be a zoned one. AC zoning allows for independent control of distinct areas of the house. In this case, the two distinct areas will be the lower and upper levels. This independent control means that you can set different temperatures on the two levels since they have different cooling needs.
Set the Thermostats Correctly
If you already have a zoned AC, then set your thermostats correctly to enjoy the benefit of the system. Note that warm air rises and cold air falls. This means the upper level will be warmer and require more cooling than the lower level. This means you should set the upstairs thermostat to your desired temperature, and then set the downstairs thermostat to a slightly lower temperature (a one or two-degree difference is adequate). The falling cold air from the upper level will fall and compensate for the temperature difference, leading to comfortable temperatures on both levels.
Isolate the Two Floors
A zoned AC works best if it is able to cool the two zones independently without air from one zone mixing up with the air in another zone. This means you should do your best to isolate the two levels from each other. For example, there should be a door or a heavy curtain separation the upper and lower floor. The attic insulation should also be adequate to minimize outside temperature influence for each zone.
Keep the Thermostat Fan Setting 'On'
If you have to use one AC to cool the two levels, then it's best to set the thermostat to 'on' rather than 'auto.' With the thermostat set to 'auto,' the AC fan will only run during active cooling when the AC is running. This interferes with air circulation, and you need efficient air circulation to distribute the cool air uniformly. Setting the thermostat fan to 'on' means the fan runs all the time, efficient air circulation happens, and even cooling becomes possible.
You will also need to maintain your AC to enjoy comfortable temperatures in your house whether the house is multistory or not. Consult an air conditioning maintenance services technician for further help on maintaining even cooling in your two-story house.