air conditioner

Sizing Your New Air Conditioner

Have you been thinking about upgrading your air conditioner this year? If so, it’s important that you familiarize yourself with Manual J. By educating yourself on this valuable load calculation tool and insisting that your HVAC contractor uses it, you’ll enjoy the highest levels of efficiency and comfort possible.

What is Manual J and how does it work?

Manual J is a tool that’s utilized by heating and cooling professionals in order to determine the sensible and latent cooling loads of your home. Your home’s sensible cooling load will tell your contractor how much heat your air conditioner should be able to remove from your home on the warmest day of the summer, whereas the latent cooling load will reveal how much moisture it will need to be able to combat under worst-case conditions.

In order to calculate these loads, an HVAC technician must consider numerous factors including:

Home size in square feet
House orientation
Number of windows and window locations
Number of household occupants
Local climate
Heat-producing appliances
Current insulation levels
Why is Manual J so important?

Many homeowners make the mistake of believing that selecting a large system will cover all of their needs. Unfortunately, this couldn’t be further from the truth. An air conditioner that’s too large for a home’s cooling needs will run inefficiently and drive up energy bills. The system will cycle on and off frequently as it quickly blasts cold air into your house, satisfies the thermostat requirement and turns off again.

In addition to creating efficiency problems, this also renders the system unable to properly dehumidify your home. Ultimately, this could lower your indoor air quality and create health issues as a result of the growth of mold and mildew. Because of this, it’s imperative that homeowners hire a professional to perform a load calculation before purchasing and installing a new air conditioning system.

For more information on Manual J, or to schedule a professional load calculation on your home, visit our website at or contact the professionals at Harbin Heating & Air. We’re proud to serve residents of North Ms. North Al. & North West Tenn.