Sizing Ductwork | Is My Ductwork Size Too Narrow?

A functional HVAC system does more than heat or cool air, it is also responsible for circulating that air throughout a property via ductwork. In order to do this efficiently, it’s important that the ductwork in a space is properly installed and fitted based on the needs of the HVAC system.

But how does one go about sizing ductwork? How do you figure out the proper ductwork size for a certain space? Let the HVAC pros at Aire Serv^® help with your ductwork dilemma!

Sizing Ductwork

An efficient HVAC system relies upon an appropriate amount of heating or cooling for a given space. This translates to a room or entire dwelling that is comfortably conditioned without using more energy than is needed. To determine how much heat or air conditioning a home actually needs, HVAC service professionals rely on load calculations.

Let’s break down what goes into this process:

What Is a Load Calculation?

Essentially, a load calculation determines how much heat (or air condition) a room will require. This is measured in cubic feet of airflow per minute (CFM).

How Is Load Calculation Determined?

An HVAC service professional will perform a room-by-room load calculation of the entire dwelling or space. This info is put into a protocol called Manual J, which calculates the load for the entire space.

How Does Load Calculation Translate to Duct Size?

The load calculation (heating requirement of the space) is factored against the output capability of the furnace or AC. Using this “output versus requirement” calculation, a chart can be used to determine the appropriate duct size for the space.

Duct, Duct, Goose

Hopefully, everything goes according to plan and the calculations are correct. But what happens if the ductwork is incorrectly sized, such as being too small?

Here are a few possible scenarios:

• Duct Call
  Ducts that are undersized will increase the static pressure, which will result in excessive noise as air moves through the system. It is often loud enough to be distracting, so it will not be difficult to overlook and should be addressed, as undersized ducts overwork the heating unit.
• Oversized Duct
  On the other hand, a duct that is too large will result in less heated or cooled air reaching the intended destination. This means that rooms could be under conditioned. This also puts a strain on the heating or cooling unit, as it works to reach the unmet demand.
• Low Duct Dividends
  Improper duct sizing or layout could also result in insufficient returns. Without proper duct layout or with insufficient return vents, not enough air is pulled from the room back into the HVAC system. The outcome is unbalanced air pressure and rooms that are stuffy and poorly ventilated.

Duct Sizing Is No Match for Aire Serv’s HVAC Experts

Finding and fitting the proper ductwork to match your HVAC system is essential to efficient and comfortable heating and cooling. To make sure your ductwork size is the perfect fit for your home or business, go with the pros! Call Aire Serv today or request an appointment online and take the guesswork out of your ductwork!