Let’s start by saying that this is not a discussion about doing load calculations vs. sizing by square footage. A load calculation is an absolute must! But if energy efficiency and comfort is your goal then sizing equipment doesn’t stop there.

Here in Western North Carolina, we just experienced Helene so I’ll use a bucket as an analogy. If you got a 5 gallon bucket to carry flushing water to your toilet, would you be carrying exactly 5 gallons each time? Not exactly. It depends on whether you have a lid, how much spills out, or how much you’re willing to carry. The output of your HVAC also depends on varying factors.

You probably already know not to oversize an AC system for obvious reasons. But once you’ve correctly determined the size you need, who’s to say the “3 ton” system you chose actually puts out 36,000 btu/h (3 x 12,000 btu)? When sizing equipment, you have to look beyond the nominal tonnage. Depending on the combination installed, many systems produce less than the rated capacity, and possibly even less than the required airflow. Other factors like sensible cooling capacity vs. moisture removal need to be compared against the Manual J load calculation. If you’re a technician, you might be saying “I’ll just turn the blower speed down to get the needed dehumidification.” But at that adjusted speed, how do you know the system is capable of providing the efficiency and the volume of airflow that the ductwork is designed for?

Is it possible to know? Yes, and as a small business we understand it’s hard to find time to work through all these details. Feel free to contact us if you need some guidance on how to find equipment that matches your needs.