IT’S ALL ABOUT “AIR!”
First, your home’s air conditioning system must be sized correctly to provide the proper CFM of air and BTUs of cooling to each room of your home.
What is CFM?
CFM (Cubic Feet per Minute) is a measure of volume of airflow rate. Visualize a basketball. A basketball is approximately 1 cubic foot in volume.
How many CFM’s does your system require?
For example, a typical 3 ton system (36,000 BTUs) requires a minimum of 1,050 CFM to a maximum of 1,200 CFM to perform to manufacturer’s specifications.
What are BTUs?
(British thermal unit) – 1 BTU is equal to the heat produced by burning a single wooden match or can be defined as the amount of heat required to raise the temperature of 1 pound of water by 1°F.
Bedroom airflow issues — how to know if it is a lack of supply air or lack of return air:
1st – Does the room cool fine during the day with the entrance door open?
2nd – Is your problem only when the door is closed for privacy issues?
3rd – If the room cools satisfactorily and only has issues when the door is closed, add a properly sized return air grill with duct work ran back to the air handler plenum.
4th – If cooling is not adequate with door open, increase airflow supply, enlarge supply duct or add additional supply register with accompanying duct work coming from supply air plenum, plus add a return grill with accompanying duct work ran back to return plenum for good performance.
NOTE: The new building code requires all major rooms to have properly sized return air grills to allow free flow of return air back to air handler.