Air Conditioning Size Explained
The International Energy Conservation Code recommends sizing HVAC systems to maintain 75 degrees indoors while it is 92 degree outdoors. The recommendation is under normal operating conditions for the greater Atlanta area. That is the textbook answer.
Load Calculations to help determine Air Conditioning Size
Performing a load calculation (simplified) is a scientific process where the walls, ceilings, doors, floors, and window areas are calculated and valued based on their respective heat transfer rates. Within the calculations values, there are assigned values including temperature gains from people, internal heat generation, infiltration and duct loss. For the most part, these values work out fine. But there are many variables that affect the results including rate of infiltration, alterations to the structure, shade, improper installation of insulation, open chases within the structure, attic ventilation, how often and long an oven is on or the drier runs. Other factors include how often the doors are opened or if an exhaust fans run to clear out moisture from a shower have bearing.
Incorrect Air Conditioning Size Will Not Control Humidity Well
You would think the simple solution is to just install a much bigger air conditioning system than you need so you can be as cool as you want whenever you want. That is where it gets really interesting. The larger the air conditioner the less control it has on humidity. In order to keep humidity levels under control, the cooling has to have substantial run time to wick out the moisture. If you were to install a five-ton unit, when you only needed a three-ton air conditioning system, then you may be able to keep it in the low seventies inside when it’s about a hundred degrees outside but you won’t feel comfortable because of high humidity indoors. This problem may even cause mold to grow in the walls and closets.
Two-Speed Air Conditioning System in combination with Correct Air Conditioning Size is the best solution for Atlanta area homes.
A two-speed air conditioning system can help greatly in our southern climate. This type of system can be oversized a bit to allow for extreme temperatures or summer entertaining without turning your space into a steam room. The key is the ability to run at low speed and run a long time without overcooling.
When it’s 95 degrees outside and your air conditioning unit runs all the time during the day while not maintaining the exact temperature the thermostat is set on but maintains in the evening, it may just mean that your system is sized with the proper balance. No problems may be occurring.
On the other hand, there may be a problem if your unit has to run into the early hours of the morning before it “catches up” with the thermostat temperature. If your home is very humid, you have lots of dust and your utility bills are extreme, you need to seek some professional HVAC help.
Solutions on how to figure out your home’s correct Air Conditioning Size
To figure out if your air conditioning size is correct, call Empire Heating and Air Conditioning at 404-294-0900 so one of our technicians can evaluate your system and get you headed in the right direction.